Alert archive / Wisconsin / Frost Advisories in 2026

Frost Advisory 2, NWS Green Bay, WI

April 30, 20269 counties in Wisconsin

NWS Green Bay, WI issued this frost advisory at Apr 30, 2026, 1:31 PM CDT for 9 counties in Wisconsin. It took effect at May 1, 2026, 12:00 AM CDT. It was in force for 8 hr.

The area

The counties it named.

The facts

Issued
Apr 30, 2026, 1:31 PM CDT (18:31 UTC)
In effect from
May 1, 2026, 12:00 AM CDT
Expired
May 1, 2026, 8:00 AM CDT
In force
8 hr
Issued by
NWS Green Bay, WI

Counties Brown County, WI, Calumet County, WI, Door County, WI, Kewaunee County, WI, Manitowoc County, WI, Outagamie County, WI, Shawano County, WI, Waupaca County, WI, Winnebago County, WI

The radar

The Green Bay radar (KGRB), 11 km from the middle of the area, began a volume at 18:32 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Detroit, MI (KDTX), launched 12:00Z, 6.5 hours before the alert went out and 426 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Detroit, MI at 12:00Z on 2026-04-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Detroit, MI at 12:00Z on 2026-04-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -7 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
2 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
455 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
-7 m²/s²
0-3 km storm-relative helicity
15 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

454 
WWUS73 KGRB 301831
NPWGRB

URGENT - WEATHER MESSAGE
National Weather Service Green Bay WI
131 PM CDT Thu Apr 30 2026

WIZ030-035-036-045-010315-
/O.NEW.KGRB.FZ.W.0001.260501T0500Z-260501T1300Z/
Marathon-Wood-Portage-Waushara-
Including the cities of Wautoma, Marshfield, Stevens Point, Plover,
Redgranite, Wausau, and Wisconsin Rapids
131 PM CDT Thu Apr 30 2026

...FREEZE WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 8 AM CDT
FRIDAY...

* WHAT...Sub-freezing temperatures as low as 28 expected.

* WHERE...Marathon, Portage, Waushara, and Wood Counties.

* WHEN...From midnight tonight to 8 AM CDT Friday.

* IMPACTS...Frost and freeze conditions could kill crops, other
  sensitive vegetation and possibly damage unprotected outdoor
  plumbing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

WIZ022-031-037>040-048>050-010315-
/O.NEW.KGRB.FR.Y.0002.260501T0500Z-260501T1300Z/
Door-Shawano-Waupaca-Outagamie-Brown-Kewaunee-Winnebago-Calumet-
Manitowoc-
Including the cities of Sturgeon Bay, Brillion, Appleton, New London,
Chilton, Oshkosh, Shawano, Luxemburg, Two Rivers, Manitowoc, Green
Bay, Fish Creek, Neenah, Menasha, Sister Bay, New Holstein, Waupaca,
Clintonville, and Kewaunee
131 PM CDT Thu Apr 30 2026

...FROST ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 8 AM CDT
FRIDAY...

* WHAT...Temperatures as low as 31 will result in frost formation.

* WHERE...Calumet, Manitowoc, Winnebago, Brown, Door, Kewaunee,
  Outagamie, Shawano, and Waupaca Counties.

* WHEN...From midnight tonight to 8 AM CDT Friday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive
  outdoor plants may be killed if left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For more information, visit us at http://www.weather.gov/GreenBay
3 follow-up statements
832 
WWUS73 KGRB 010232
NPWGRB

URGENT - WEATHER MESSAGE
National Weather Service Green Bay WI
932 PM CDT Thu Apr 30 2026

WIZ030-035-036-045-011045-
/O.CON.KGRB.FZ.W.0001.260501T0500Z-260501T1300Z/
Marathon-Wood-Portage-Waushara-
Including the cities of Stevens Point, Redgranite, Plover, Wausau,
Wisconsin Rapids, Wautoma, and Marshfield
932 PM CDT Thu Apr 30 2026

...FREEZE WARNING REMAINS IN EFFECT UNTIL 8 AM CDT FRIDAY...

* WHAT...Sub-freezing temperatures as low as 29 expected.

* WHERE...Marathon, Portage, Waushara, and Wood Counties.

* WHEN...Until 8 AM CDT Friday.

* IMPACTS...Frost and freeze conditions could kill crops, other
  sensitive vegetation and possibly damage unprotected outdoor
  plumbing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

WIZ022-031-037>040-048>050-011045-
/O.CON.KGRB.FR.Y.0002.260501T0500Z-260501T1300Z/
Door-Shawano-Waupaca-Outagamie-Brown-Kewaunee-Winnebago-Calumet-
Manitowoc-
Including the cities of Oshkosh, Luxemburg, New London, Clintonville,
Chilton, Two Rivers, Waupaca, Brillion, Green Bay, Manitowoc, New
Holstein, Shawano, Sister Bay, Sturgeon Bay, Appleton, Fish Creek,
Kewaunee, Neenah, and Menasha
932 PM CDT Thu Apr 30 2026

...FROST ADVISORY REMAINS IN EFFECT UNTIL 8 AM CDT FRIDAY...

* WHAT...Temperatures as low as 31 to 36 will result in areas of
  frost.

* WHERE...Calumet, Manitowoc, Winnebago, Brown, Door, Kewaunee,
  Outagamie, Shawano, and Waupaca Counties.

* WHEN...Until 8 AM CDT Friday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive
  outdoor plants may be killed if left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For more information, visit us at http://www.weather.gov/GreenBay

GK
853 
WWUS73 KGRB 010704
NPWGRB

URGENT - WEATHER MESSAGE
National Weather Service Green Bay WI
204 AM CDT Fri May 1 2026

WIZ030-035-036-045-011300-
/O.CON.KGRB.FZ.W.0001.000000T0000Z-260501T1300Z/
Marathon-Wood-Portage-Waushara-
Including the cities of Stevens Point, Wausau, Redgranite, Wisconsin
Rapids, Wautoma, Plover, and Marshfield
204 AM CDT Fri May 1 2026

...FREEZE WARNING REMAINS IN EFFECT UNTIL 8 AM CDT THIS MORNING...

* WHAT...Sub-freezing temperatures as low as 29 expected.

* WHERE...Marathon, Portage, Waushara, and Wood Counties.

* WHEN...Until 8 AM CDT this morning.

* IMPACTS...Frost and freeze conditions could kill crops, other
  sensitive vegetation and possibly damage unprotected outdoor
  plumbing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

WIZ022-031-037>040-048>050-011300-
/O.CON.KGRB.FR.Y.0002.000000T0000Z-260501T1300Z/
Door-Shawano-Waupaca-Outagamie-Brown-Kewaunee-Winnebago-Calumet-
Manitowoc-
Including the cities of Brillion, Sister Bay, Sturgeon Bay,
Clintonville, Kewaunee, Shawano, Fish Creek, Manitowoc, Neenah, Two
Rivers, Chilton, New Holstein, Green Bay, New London, Luxemburg,
Appleton, Oshkosh, Menasha, and Waupaca
204 AM CDT Fri May 1 2026

...FROST ADVISORY REMAINS IN EFFECT UNTIL 8 AM CDT THIS MORNING...

* WHAT...Temperatures as low as 31 to 36 will result in areas of
  frost.

* WHERE...Calumet, Manitowoc, Winnebago, Brown, Door, Kewaunee,
  Outagamie, Shawano, and Waupaca Counties.

* WHEN...Until 8 AM CDT this morning.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive
  outdoor plants may be killed if left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For more information, visit us at http://www.weather.gov/GreenBay

JG
976 
WWUS73 KGRB 011256
NPWGRB

URGENT - WEATHER MESSAGE
National Weather Service Green Bay WI
756 AM CDT Fri May 1 2026

WIZ030-035-036-045-012100-
/O.EXP.KGRB.FZ.W.0001.000000T0000Z-260501T1300Z/
/O.NEW.KGRB.FZ.W.0002.260502T0500Z-260502T1300Z/
Marathon-Wood-Portage-Waushara-
Including the cities of Wausau, Stevens Point, Redgranite, Plover,
Wautoma, Marshfield, and Wisconsin Rapids
756 AM CDT Fri May 1 2026

...FREEZE WARNING WILL EXPIRE AT 8 AM CDT THIS MORNING...
...FREEZE WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 8 AM CDT
SATURDAY...

* WHAT...Sub-freezing temperatures as low as 26 expected.

* WHERE...Marathon, Portage, Waushara, and Wood Counties.

* WHEN...From midnight tonight to 8 AM CDT Saturday.

* IMPACTS...Frost and freeze conditions could kill crops, other
  sensitive vegetation and possibly damage unprotected outdoor
  plumbing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

WIZ022-031-037>040-048>050-012100-
/O.EXP.KGRB.FR.Y.0002.000000T0000Z-260501T1300Z/
/O.NEW.KGRB.FZ.W.0002.260502T0500Z-260502T1300Z/
Door-Shawano-Waupaca-Outagamie-Brown-Kewaunee-Winnebago-Calumet-
Manitowoc-
Including the cities of Fish Creek, Manitowoc, Brillion, Sister Bay,
Menasha, Shawano, New Holstein, Neenah, Chilton, Sturgeon Bay, Two
Rivers, Clintonville, Luxemburg, Oshkosh, Waupaca, Green Bay,
Appleton, New London, and Kewaunee
756 AM CDT Fri May 1 2026

...FROST ADVISORY WILL EXPIRE AT 8 AM CDT THIS MORNING...
...FREEZE WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 8 AM CDT
SATURDAY...

* WHAT...Sub-freezing temperatures as low as 28 expected.

* WHERE...Calumet, Manitowoc, Winnebago, Brown, Door, Kewaunee,
  Outagamie, Shawano, and Waupaca Counties.

* WHEN...From midnight tonight to 8 AM CDT Saturday.

* IMPACTS...Frost and freeze conditions could kill crops, other
  sensitive vegetation and possibly damage unprotected outdoor
  plumbing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For more information, visit us at http://www.weather.gov/GreenBay

Bersch

What forecasters said that day

The local office's own words before this frost advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Green Bay, WI wrote its last area forecast discussion before this frost advisory went out at Apr 30, 12:38 PM CDT, 53 minutes earlier. Its key messages:

  • Another round of rain showers today, mixed with snow north. Small chance of showers on Friday. Dry Saturday, then chances for more showers Sunday into next week.
  • Frost Advisory for central WI to the Fox Valley early this morning. Additional frost and freeze headlines expected over central and east central WI tonight. Freeze looking likely for much of the area Friday night.
  • Minor flooding lingers on the Wolf River and Winnebago system. Water levels will slowly recede given lack of significant rainfall.
  • Below normal temperatures expected through most of the period.
Area forecast discussion, Apr 30, 12:38 PM CDT, 53 minutes before
Area Forecast Discussion
National Weather Service Green Bay WI
1238 PM CDT Thu Apr 30 2026

.KEY MESSAGES...

- Another round of rain showers today, mixed with snow north.
  Small chance of showers on Friday. Dry Saturday, then chances
  for more showers Sunday into next week.

- Frost Advisory for central WI to the Fox Valley early this
  morning. Additional frost and freeze headlines expected over
  central and east central WI tonight. Freeze looking likely for
  much of the area Friday night.

- Minor flooding lingers on the Wolf River and Winnebago system.
  Water levels will slowly recede given lack of significant
  rainfall.

- Below normal temperatures expected through most of the period.

&&

.DISCUSSION...
Issued at 154 AM CDT Thu Apr 30 2026

Near term through tonight...Showers have exited early this
morning. Patches of stratocu clouds will lead to variable temps
early this morning, but with temps in the mid to upper 30s, some
frost is expected where skies can clear. Attention is on shortwave
north of Lake Superior in general troughing. Expect this wave to
dip over western Great Lakes by this afternoon, resulting in
another round of showers from mid morning through early evening.
Colder aloft this time around, with H85 temps over northern WI
bottoming out around -5c. Soundings look to support snow more than
rain. A smattering of rain/snow or just snow showers seen in much
of the high-res guidance especially north. Sfc temps, ground
temps appear too warm and snowfall rates too low to lead to any
accumulation on the ground, but snow in the air is likely from
Rhinelander northward.

Once showers end this evening, another chilly night is in store,
but similar to early this morning, based on upstream obs and HREF
guidance, there will be a fair amount of stratocu to modulate
temps. Nevertheless, Frost/Freeze headlines will be needed in some
shape or form again. With current headlines out for early this
morning, will let dayshift issue the new set of headlines.

Precipitation chances beyond today: One last shortwave set to drop
across on Friday. With a nod to persistence and since some models
are showing at least light QPF, opted to add some slight chances
for showers. Ptype looking mainly like rain as colder air aloft
does ease. Decent signal we sneak in at least one dry day Saturday
with weak ridging aloft and since the area will be well downstream
of stronger shortwave/sfc trough working across south central
Canada and northern Plains. As that system arrives for Sunday,
expect renewed chance for showers. MUCAPES up to 300-400J/kg with
plume of mid- level lapse rates over 7c/km support slight chance
of thunder. Stronger trough crosses Monday so chances for showers
continue. Better thunder chances may be south and east of the area
by that time following the plume of steeper mid-level lapse
rates. Still some uncertainty on those details though. Unsettled
weather to close out the rest of the forecast as we return to a
regime similar to what we are seeing at present with northwest
flow aloft and shortwaves riding across the area.

Frost/Freeze Headlines: Sfc ridge overhead with less troughing
aloft will promote better chance of clearing and light winds
Friday night. Expect temps widespread temps at or below freezing.
Thus, a widespread freeze is looking likely. Recent LREF runs
point to over 90% chance of seeing temps less than 32, even into
the Fox Valley, with a 50-80% chance of seeing temps less than 28
for portions of central WI. Beyond Friday night, chances of temps
less than 32 decrease markedly as we get back into a return flow
pattern.

Temperatures: Northwest flow of Canadian air keeps temperatures
below normal through Saturday. For reference, normal highs are now
in the upper 50s to around 60. Some moderation in temperatures (to
near normal) should occur Sunday and/or Monday ahead of cold
fronts that move through, but reinforcing shots of Canadian air
will follow, leading to cooler than normal temps much of next
week. Per CPC days 6-10/8-14 day outlooks, appears this cooler
pattern will persist through at least mid May.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1237 PM CDT Thu Apr 30 2026

VFR conditions prevail this afternoon at all sites, though this
morning a couple of sites experienced some MVFR ceilings. For GRB
and ATW, VFR conditions will prevails for the rest of the evening
until the overnight period, where chances of MVFR ceilings exceed
40% from 03Z to 10Z and especially around 07Z when probabilities
exceed 60%. GRB/ATW then experiences SCT or less cloud cover after
11Z Friday. MTW will have a more prolonged period of MVFR and low-
MVFR, including a roughly 30% chance for IFR ceilings from 06-10Z.
AUW/CWA/RHI are over 75% likely to remain VFR for the entire period
(highest chances of MVFR at RHI this afternoon with around 30$
chances of -SHRA), though will experience some wind shifts from the
WNW to the N throughout this evening before light and variable winds
resume overnight, with N to NW winds expected after 15Z Friday.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WI...None.
MARINE...None.

&&

DISCUSSION...
AVIATION...GS
Hazardous weather outlook, Apr 30, 10:17 AM CDT, 3 hours 14 minutes before
Hazardous Weather Outlook
National Weather Service Green Bay WI
1017 AM CDT Thu Apr 30 2026

WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-011530-
Vilas-Oneida-Forest-Florence-Northern Marinette County-Lincoln-
Langlade-Menominee-Northern Oconto County-Door-Marathon-Shawano-
Wood-Portage-Waupaca-Outagamie-Brown-Kewaunee-Waushara-Winnebago-
Calumet-Manitowoc-Southern Marinette County-
Southern Oconto County-
1017 AM CDT Thu Apr 30 2026

This Hazardous Weather Outlook is for north-central and northeast
Wisconsin.

.DAY ONE...This Afternoon and Tonight

Minor flooding continues on the Wolf River and Lake Winnebago
system.

Areas of frost are expected tonight. Frost or freeze headlines
will likely be needed again.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Minor flooding is forecast to continue on the Wolf River and Lake
Winnebago system.

Frost or freeze headlines will likely be needed across all of
central Wisconsin, the Fox Valley and lakeshore areas Friday
night.

There is a small chance for thunderstorms on Sunday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today or tonight.

LMZ521-522-541>543-011530-
The Bay of Green Bay south of a line from Cedar River MI to Rock
Island Passage-Lake Michigan from Washington Island to Sheboygan-
1017 AM CDT Thu Apr 30 2026

This Hazardous Weather Outlook is for portions of northwest Lake
Michigan and the waters of Green Bay.

.DAY ONE...This Afternoon and Tonight

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Conditions hazardous for Small Craft may occur on Monday.
Otherwise, the probability for widespread hazardous weather is
low.

The office that day

Everything else NWS Green Bay, WI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 30, 1:31 PM CDTFreeze WarningGRBMarathon, Portage, Waushara, Wood18 hr

Nearby

Frost Advisories in Wisconsin, 2026Every frost advisory in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.