On June 30, 2026, an oppressive tropical airmass fueled by extreme heat warnings collided with a sharp mid-level shortwave across the NWS Buffalo CWA, prompting the Storm Prediction Center to issue a Severe Thunderstorm Watch as strong boundary-layer destabilization produced widespread severe convection across Central New York and the North Country. NWS Buffalo Area Forecast Discussions…
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS BUF wrote it up.
On June 30, 2026, an oppressive tropical airmass fueled by extreme heat warnings collided with a sharp mid-level shortwave across the NWS Buffalo CWA, prompting the Storm Prediction Center to issue a Severe Thunderstorm Watch as strong boundary-layer destabilization produced widespread severe convection across Central New York and the North Country. NWS Buffalo Area Forecast Discussions highlighted surging moisture and extreme instability that unleashed powerful multi-cell clusters and isolated supercells, leading to severe straight-line microbursts with winds up to 100 mph and an EF-1 tornado touchdown in Lewis County. Concurrently, deep warm-cloud processes and precipitable water levels approaching 2.0 inches fueled torrential precipitation efficiency, driving Weather Prediction Center Excessive Rainfall concerns for localized flash flooding in poor-drainage areas. As the pre-frontal convective line swept east toward nightfall, loss of daytime heating and post-frontal drying rapidly stabilized the region, bringing an end to the severe weather threat into the overnight hours.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Buffalo, NY wrote its last area forecast discussion before the first event at Jun 30, 5:27 AM EST, 6 hours 44 minutes earlier. Its key messages:
Area Forecast Discussion
National Weather Service Buffalo NY
627 AM EDT Tue Jun 30 2026
.WHAT HAS CHANGED...
Have adjusted PoPs a bit further for today to keep these in
line with current upstream radar trends.
&&
.KEY MESSAGES...
1) Dangerous heat and humidity through Friday, then more unsettled
with slowly lessening heat/humidity for the holiday weekend.
2) Scattered strong to severe thunderstorms are possible today as a
warm front crosses the region...and then again on Wednesday.
&&
.DISCUSSION...
KEY MESSAGE 1...Dangerous heat and humidity through Friday, then
more unsettled with slowly lessening heat/humidity for the holiday
weekend.
Guidance remains in lockstep on upper level ridging building across
the eastern CONUS through Thursday...with the core of the ridge
strengthening to near 600 dm while drifting east from the Tennessee
Valley to Virginia. After that time...a series of shortwave impulses
digging southeastward across eastern Canada will help to slowly
buckle and flatten the ridge Friday through the holiday weekend...
with its core correspondingly settling southwestward into the
southern Plains/southeastern States. Under this regime...850 mb
temps will climb to around +20C by later this afternoon...then will
remain around or even a little above +20C through at least Thursday
and possibly even Friday...before pulling back into the mid to upper
teens over the weekend.
Following the passage of a warm front...the above will translate
into highs climbing into the upper 80s and lower 90s across much of
the area today...save for the North Country where possible
convection and cloud cover associated with the warm front may hold
temperatures lower. Coupled with dewpoints surging into the lower
70s...this will result in fairly widespread heat indices in the 95
to 100 range today...again save for perhaps far interior portions of
the Southern Tier and the North Country. As such...Heat Advisories
remain in effect areawide for today...though it's possible that true
advisory-level conditions may not actually be realized across the
North Country given the aforementioned potential for convection/
cloud cover and its influence on high temperatures there.
The heat and humidity will then reach its peak Wednesday and
Thursday...when daytime highs away from lake influences/the higher
terrain will surge into the lower to mid 90s for many areas...with a
few of our normal hot spots possibly even reaching the upper 90s. At
the same time...dewpoints will climb into the lower-mid 70s
Wednesday and then should linger in the lower 70s Thursday...
supporting oppressive heat indices in the upper 90s to lower 100s
for much of our lower elevations both afternoons...with some
locations from Niagara/Orleans counties eastward across the Finger
Lakes and over to Oswego County possibly even seeing these briefly
reach heat warning criteria (105F) both days.
Gradual lessening of the heat and humidity will then begin on Friday
and continue through the holiday weekend as the strong upper ridge
slowly flattens and retreats southwestward...with this trend
supported by both a corresponding slow cooling of temps aloft and an
increased potential for convection as we become increasingly more
subject to shortwave disturbances rippling along the northern
periphery of the ridge. At this point feel that we may see heat
indices pull back enough to peak in the advisory range across
portions of the area on Friday...with non-headline worthy conditions
then following for the weekend...though both Saturday and Sunday
still look to be rather warm and humid.
Between today and Friday...downright sultry nighttime temps in the
lower to mid 70s and high humidity will also offer little relief
from the heat for those without air conditioning...and will increase
the likelihood of heat-related illness for vulnerable populations.
Given all the above and the continued potential for some areas to
reach heat warning criteria (105 F) Wednesday and Thursday...an
Extreme Heat Watch remains in place from the Niagara Frontier
eastward across the Finger Lakes and Oswego county for the Wednesday
through Friday time frame...though I am not as bullish regarding
this potential as blended guidance (which continues to exhibit its
typical high biases with temps/dewpoints) would suggest. This is
especially true for much of the Buffalo Metro Area...which will see
temps held back some from those further inland due to the
southwesterly flow off the cooler waters of Lake Erie...a factor
that will probably make it difficult to reach true heat warning
criteria there.
KEY MESSAGE 2...Scattered strong to severe thunderstorms are
possible today as a warm front crosses the region...and then again
on Wednesday.
A warm frontal boundary marking the eastern edge of the incoming
oppressively hot and humid airmass will slowly make its way east
across our area today. As this occurs...an attendant increase in
isentropic ascent/instability along with the potential for one or
more convectively-augmented shortwaves rippling southeast along this
boundary bringing the potential for at least some scattered showers
and storms to the area.
Initial complex of storms along this boundary continues to slowly
make its way east-southeastward across Southern Ontario as of this
writing...with the strongest activity persisting along its southern
flank. This should continue to slide east-southeastward and tend to
weaken through this morning...though expect that at least some of
this should survive long enough (along with any other widely
scattered activity that might develop along the front) to support
some scattered showers and storms across areas south of Lake Ontario
this morning. A number of CAMs then show the potential for another
MCS (currently well to the north of the first batch over
Ontario/Quebec) to dive southeastward somewhere across the North
Country/Saint Lawrence Valley this afternoon...with additional
activity also potentially forming along its southern flank. With
this second round...effective bulk shear values of 35-45 kts and
potentially moderate instability could support an initial few
transient supercells evolving into one or more clusters/bowing
segments. At this point damaging winds and large hail remain the
primary risks with this latter activity...however an isolated
tornado or two cannot be ruled out within any initial supercells.
Given this the North Country remains within a Slight Risk (level 2
of 5) area on the new SPC Day 1 Convective Outlook...though
uncertainty persists regarding exactly where this second round of
convection will track (i.e., whether this reaches our area...or
tracks further to the east across eastern New York and Vermont).
On Wednesday...another such cluster of storms could develop over
Canada and again dive southeastward across the North Country/
Northern New York...with strong instability again supporting a risk
for strong to severe storms with damaging winds/hail the main
threats. This being said...considerable uncertainty persists as to
whether this will actually occur given much weaker overall forcing
for ascent compared to today. With this in mind...the current SPC
Marginal Risk area for the North Country on Wednesday looks quite
reasonable.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
A warm front will push across the region today. Initial cluster of
storms along this boundary (currently just north of Toronto) should
continue to push east-southeastward and tend to weaken this
morning...with its remnants (along with any other widely scattered
convection that forms along the front) bringing a chance of
showers/thunderstorms to areas south of Lake Ontario this morning.
While confidence remains low on the exact timing and placement of
these...brief/localized IFR or lower conditions will be possible in
any heavier showers or storms.
As we push through this afternoon and early evening...there is the
potential for another complex of storms to dive southeastward out of
Canada...with this and/or any additional convection that forms on
its flank affecting the North Country and perhaps eastern portions
of the Finger Lakes. Reductions to IFR or lower will also be
possible within this convection...some of which could be locally
strong to severe with strong wind gusts and large hail the main
threats.
Outside of any convection...general VFR conditions will prevail
today.
Tonight mainly dry weather and VFR flight conditions should tend to
prevail...though some additional showers/storms and associated
restrictions cannot be completely ruled out across the North
Country. Later on tonight...some patchy MVFR stratus could form
across the interior of the Southern Tier and North Country.
Outlook...
Wednesday...Possible MVFR ceilings across the Southern Tier and
North Country early...otherwise mainly VFR with a chance of showers
and thunderstorms east of Lake Ontario.
Thursday...Mainly VFR.
Friday and Saturday...Mainly VFR with a chance of showers and
thunderstorms.
&&
.MARINE...
A warm front will pass across the region today, with modest to
moderate southwesterlies then following for the remainder of the
week.
The warm frontal passage may also bring the potential for at least
some scattered showers and thunderstorms today...some of which could
produce locally higher winds and waves. This risk will be greatest
across Lake Ontario and the Saint Lawrence River...particularly with
increasing eastward extent.
&&
.CLIMATE...
Dangerous heat and humidity are expected across western and
north central NY this week. Here are the record maximum and high
minimum temperatures for Buffalo, Rochester, and Watertown.
6/30 7/1 7/2 7/3
Buffalo, NY
High Max 94(1963) 93(1963) 94(1966) 94(1949)
High Low 73(1941) 75(1901) 75(1931) 74(1911*)
Rochester, NY
High Max 96(1964) 96(1901) 99(1931) 100(1911)
High Low 72(2014) 76(1931) 76(1931*) 75(1911)
Watertown, NY
High Max 89(1977) 92(1967) 92(1966) 91(1966)
High Low 73(2014*) 74(2014) 73(2002) 74(1973)
Average Temperatures for June 30-July 3
Buffalo
Max 79
Min 62
Rochester
Max 82
Min 62
Watertown
Max 78
Min 57
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Heat Advisory from noon today to 8 PM EDT this evening for
NYZ001>008-010>014-019>021-085.
Extreme Heat Watch from Wednesday afternoon through Friday
evening for NYZ001>006-010-011-013-014.
MARINE...None.
&&
DISCUSSION...JJR
AVIATION...JJR/TMA
MARINE...JJR
CLIMATE...WFO BUFHazardous Weather Outlook National Weather Service Buffalo NY 237 AM EDT Tue Jun 30 2026 NYZ012-019>021-085-010645- Wyoming-Chautauqua-Cattaraugus-Allegany-Southern Erie- 237 AM EDT Tue Jun 30 2026 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 8 PM EDT THIS EVENING... This Hazardous Weather Outlook is for portions of western New York. .DAY ONE...Today and tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Dangerous heat and humidity will continue through Friday. Maximum heat index values will likely reach the mid 90s to near 100 each afternoon. Very warm and muggy nights will offer little relief from the heat. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf NYZ001-002-010-011-010645- Niagara-Orleans-Northern Erie-Genesee- 237 AM EDT Tue Jun 30 2026 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 8 PM EDT THIS EVENING... ...EXTREME HEAT WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH FRIDAY EVENING... This Hazardous Weather Outlook is for portions of western New York. .DAY ONE...Today and tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Extreme Heat Watch. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf NYZ003>005-013-014-010645- Monroe-Wayne-Northern Cayuga-Livingston-Ontario- 237 AM EDT Tue Jun 30 2026 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 8 PM EDT THIS EVENING... ...EXTREME HEAT WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH FRIDAY EVENING... This Hazardous Weather Outlook is for portions of western and north central New York. .DAY ONE...Today and tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. There is a Marginal Risk for strong to severe thunderstorms today, with damaging winds and large hail the primary threats. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Extreme Heat Watch. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf NYZ006-010645- Oswego- 237 AM EDT Tue Jun 30 2026 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 8 PM EDT THIS EVENING... ...EXTREME HEAT WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH FRIDAY EVENING... This Hazardous Weather Outlook is for portions of central New York. .DAY ONE...Today and tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. There is a Slight Risk for strong to severe thunderstorms today, with damaging winds and large hail the primary threats. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Extreme Heat Watch. There is a Marginal Risk for strong to severe thunderstorms on Wednesday, with damaging winds and large hail the primary threats. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf NYZ007-008-010645- Jefferson-Lewis- 237 AM EDT Tue Jun 30 2026 ...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 8 PM EDT THIS EVENING... This Hazardous Weather Outlook is for portions of central New York. .DAY ONE...Today and tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. There is a Slight Risk for strong to severe thunderstorms today, with damaging winds and large hail the primary threats. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Dangerous heat and humidity will continue through Friday. Maximum heat index values will likely reach the mid 90s to near 100 each afternoon. Very warm and muggy nights will offer little relief from the heat. There is a Marginal Risk for strong to severe thunderstorms on Wednesday, with damaging winds and large hail the primary threats. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf LEZ020-040-041-LOZ030-042-062-010645- Upper Niagara River and Buffalo Harbor- Lake Erie nearshore waters from Ripley to Dunkirk- Lake Erie nearshore waters from Dunkirk to Buffalo- Lower Niagara River- Lake Ontario nearshore waters from the Niagara River to Hamlin Beach- Lake Ontario open waters from the Niagara River to Hamlin Beach- 237 AM EDT Tue Jun 30 2026 This Hazardous Weather Outlook is for portions of Lake Erie and Lake Ontario. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf LOZ043>045-063>065-010645- Lake Ontario nearshore waters from Hamlin Beach to Sodus Bay- Lake Ontario nearshore waters from Sodus Bay to Mexico Bay- Lake Ontario nearshore waters from Mexico Bay to the Saint Lawrence River-Lake Ontario open waters from Hamlin Beach to Sodus Bay- Lake Ontario open waters from Sodus Bay to Mexico Bay- Lake Ontario open waters from Mexico Bay to the Saint Lawrence River- 237 AM EDT Tue Jun 30 2026 This Hazardous Weather Outlook is for portions of Lake Ontario. .DAY ONE...Today and tonight. There is a Marginal Risk for strong to severe thunderstorms today, with strong wind gusts and large hail the primary threats. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf SLZ022-024-010645- Saint Lawrence River from Cape Vincent to Ogdensburg- Saint Lawrence River from Ogdensburg to Saint Regis- 237 AM EDT Tue Jun 30 2026 This Hazardous Weather Outlook is for the New York waters of the Saint Lawrence River. .DAY ONE...Today and tonight. There is a Slight Risk for strong to severe thunderstorms today, with strong wind gusts and large hail the primary threats. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. There is a Marginal Risk for strong to severe thunderstorms on Wednesday, with strong wind gusts and large hail the primary threats. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. This product, along with other watches, warnings, advisories, and statements issued by the National Weather Service office in Buffalo can be found on the internet at http://www.weather.gov/buf JJR
The Ft Drum radar (KTYX), 63 km away, was scanning. The volume nearest the first event began at 17:09 UTC.
10 thunderstorm wind, 1 tornado. Local standard time, as filed.
Widespread trees and power lines down in the Clayton area.
Widespread trees and power lines down in the Cape Vincent area.
There was a large branch down.
There was a large tree branch down.
Microburst #1, was determined to be caused by straight line winds in the range of 80 to 90 mph. The damage occurred shortly before 2 pm local time across roughly a half mile stretch of NY 26 just south of Denmark. The most notable damage occurred in the backyard of one of these properties where several hardwood and softwood trees were uprooted, and some vinyl siding was ripped off an adjacent house.
Delayed report. Report from Emergency Manager of numerous trees downed across Castorland. Time estimated by radar.
EF-1 tornado with maximum wind speeds in the range of 95 to 105 mph. The damage occurred right around 2 pm local time across almost a 3/4 mile stretch of Swiss Road midway between Castorland and Croghan. The track of the tornado almost paralleled the road in this stretch, but did cross at some point as it traveled in a SSE direction. Convergent damage was noted along several points, as well as a generally chaotic nature to tree damage near Widmeyer Creek.
Multiple trees, large branches, and wires down.
Microburst #2, was determined to be caused by straight line winds in the range of 95 to 105 mph. The damage occurred shortly after 2 pm local time across a small area off of Johnson Road just off NY 12 in Glenfield The most notable damage occurred in the front yard of a property where multiple hardwood trees were snapped and uprooted. Additionally, the tin roof of the home was partially peeled upwards, with some damage to the garage door as well.
There was atree down on Highway 31.
Report of a few trees and wires downed in the Town of Champion.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in New York in 2026Every state in 2026This day in weather historyThe tornado archive for New York, 2026Warnings in New York, June 2026
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1353283, 1353282, 1353285, 1353286, 1353291, 1353288, 1353281, 1353284, 1353290, 1353287, 1353289.