Hawaii, 2026Flash Flooding and Heavy Rain in Hawaii, March 20 to 23, 2026
March 20 to 23, 2026 · NWS HFO · 6 events in 3 counties and zones
A cutoff low moved in from the northwest and pulled deep tropical moisture from the south over the Hawaiian islands. This led to the development of prolonged slow moving heavy rain and thunderstorms.
Every event with a place to put it. Tap one for its entry below.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
Open the live radar over this ground
- Deaths
- 0
- Injuries
- 10
- Property damage
- $1.0 billion
- Crop damage
- $10 million
- Events
- 6
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.
A cutoff low moved in from the northwest and pulled deep tropical moisture from the south over the Hawaiian islands. This led to the development of prolonged slow moving heavy rain and thunderstorms. The heavy rain and thunderstorms caused catastrophic flooding over Oahu's North Shore and Manoa Valley.
What forecasters said that day
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 Honolulu, HI wrote its last area forecast discussion before the first event at Mar 20, 8:59 PM HST, 1 hour 1 minute earlier.
Area forecast discussion, Mar 20, 8:59 PM HST, 1 hour 1 minute before
Area Forecast Discussion
National Weather Service Honolulu HI
859 PM HST Fri Mar 20 2026
.SYNOPSIS...
In the big picture, two surface low pressure systems will continue
move slowly northeastward through the northern Hawaii region into
the weekend, producing additional periods of moderate to heavy
rain, thunderstorms, and elevated threats for flash flooding. A
combination of low level forcing and passing upper level troughs
will drive these smaller scale heavy rain band and thunderstorm
formations. Additional weather threats include strengthening south
to southwest kona winds on Saturday that will produce down
sloping wind gusts in the 30 to 45 MPH range along steep north and
east slopes of island mountain ranges lasting through Saturday
night. Improving weather trends will develop from west to east on
Monday as we transition to a wet trade wind weather pattern
lasting through the end of next week.
&&
.SHORT TERM UPDATE...
Diving into the smaller scale (mesoscale) analysis this evening,
we see a long lived low level convergence band just east of Oahu,
this band is drifting slowly eastward. A very unstable atmosphere
coupled with increasing forcing aloft from an upper level
subtropical jet stream will cause heavy rain and thunderstorms to
fill in along this low level band through the overnight hours and
through Saturday. Some caution here additional heavy rain bands
may yet develop any other island. As this current convergence band
continues to drift eastward the primary heavy rain threats in the
short term will increase over the islands of Maui County into
Saturday. Saturday night through Sunday the large scale flooding
threats increase over the Big Island of Hawaii. Hourly rainfall
rates of 2 to 3 inches are likely, even higher hourly rainfall
rates are possible under developing thunderstorms. Confidence is
growing on this forecast solution as the latest satellite imagery
trends supports this conclusion.
This is a dangerous life threatening weather pattern evolving
across the state of Hawaii through Sunday. Flash flooding is the
primary threat with damaging wind gusts possible. We will closely
monitor these small scale heavy shower and thunderstorm bands as
they develop for flooding potential across the state. Island by
island forecast impacts of these rapidly developing small scale
features are typically more predictable on an hour by hour basis.
Longer range forecasts of these smaller scale bands are extremely
challenging. Overall additional widespread rainfall amounts in the
larger scale through Sunday statewide remains in the 3 to 8 inch
range with the understanding that these smaller scale convective
cloud bands can double or sometimes triple these ranges for some
localized areas of each island.
&&
.PREVIOUS DISCUSSION...
Issued at 342 PM HST Fri Mar 20 2026
This afternoon radar (as of 3:40 PM HST) shows a large area of
moderate to heavy showers over Maui County, and scattered showers
over Kauai and Oahu. Light showers are expected to move into
northwest Big Island this evening. Winds were generally out of the
south at speeds averaging 10 to 20 mph with gusts 20 to 30 mph.
Flood warnings are still in effect on Oahu, with flood advisories
on Maui County. Rainfall amounts on Oahu in the past 6 hours were
generally in the 2 to 6 inch range, with a maximum of 8.58 inches
at Wahiawa.
The forecast remains largely unchanged, with a flood watch in
effect for all areas except the peaks on the Big Island through
Sunday. Periods of showers, heavy at times, will continue to move
through the islands. Southwest flow aloft will remain in place
thanks to an upper level trough to our west. Smaller "pieces" of
energy will move through this trough and occasionally boost the
shower activity, possibly leading to isolated thunderstorms. The
exact location of these increased showers is impossible to know
ahead of time (beyond the state of modeling science out here in
the middle of the ocean). Therefore, folks should be aware that
flooding will continue to be possible in all areas where the flood
watch has been issued.
Forecast models are reasonably consistent in keeping the axis of
heaviest rainfall over the central islands tonight and Saturday,
then shifting it slowly eastward Saturday night into Sunday. This
will slowly take the risk of flooding eastward with it.
Some drying will occur from Monday into Wednesday as trade winds
become established over the state, but windward areas will see
numerous light to moderate showers. Winds are expected to be a
little weaker both Saturday and Sunday (in most areas) than they
have been today. The exception will be the peaks on the Big
Island, where winds will approach wind advisory criteria Saturday
evening through Sunday morning. Several inches of snow are likely
to fall on the summits Saturday night into early next week.
The long range forecast shows the possibility of another trough
moving into the area from the northwest late next week. At this
time, the setup is not a kona low system, but could push a cold
front through the state. Details will become available as we get
closer in time.
&&
.AVIATION...
Bands of rain with embedded heavy showers and storms are expected
to continue over Oahu and Maui County through the night. These
rainbands are producing periods of IFR to LIFR CIGS/VSBYS, which
will persist into the weekend as an upper level trough approaches
from the west. Kauai and Big Island are expected to be mostly VFR
through tonight, with MVFR conditions possible within an
occasional shower.
Low-level winds continue to be out of the S-SSW, and may veer more
SW over the western half of the state on Saturday. Winds are
strongest over Maui county, with gusts reported up to 39 kt at
PHOG. These winds may result in localized mechanical turbulence
leeward of terrain. Winds will remain gusty through the evening,
but gradually weaken through the weekend.
AIRMET Sierra for mountain obscuration is in effect across all
islands except Kauai and the Big Island, and will likely continue
into the weekend. AIRMET Tango is in effect for moderate
turbulence downwind of terrain for Oahu and Maui county below 090.
AIRMET Zulu for light icing in the 140-FL260 layer will continue
to be a concern within deeper cloud layers associated with the
upper level disturbance.
&&
.MARINE...
Issued at 342 PM HST Fri Mar 20 2026
Light to moderate S winds may strengthen tonight as surface low
pressure west of Kauai deepens. Moderate to locally strong S/SW
prevail through Saturday, and periods of heavy showers and
thunderstorms are expected. The low will lift north on Sunday
allowing moderate N winds to develop around Kauai which will then
veer to NE and spread south. Fresh to strong NE winds may require
a Small Craft Advisory over most waters.
N swell will increase into Saturday in maintenance of moderate
swell through the weekend along N facing shores. A small,
overlapping WNW swell then arrives late Saturday and holds through
Monday. Surf along E shores remain well below average through the
weekend. NE trades then develop early next bringing increase NE
fresh swell and an increase in short period choppy surf which may
approach the High Surf Advisory threshold.
A moderate S swell slowly diminishes through today followed by a
small reinforcing SSW swell this weekend into Monday. Smaller
surf is expected along south facing shores through the remainder
of the week.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Sunday afternoon for all Hawaiian Islands.
Winter Storm Watch from Saturday evening through Sunday
afternoon for Big Island Summits.
&&
SHORT TERM DISCUSSION...Bohlin
PREVIOUS DISCUSSION...Parker
AVIATION...Evans
MARINE...JVC
In the hours before
Local storm report, Mar 20, 4:16 PM HST, 5 hours 44 minutes before
Preliminary Local Storm Report
National Weather Service Honolulu HI
416 PM HST Fri Mar 20 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1015 AM Flash Flood 2 W Waialua 21.58N 158.16W
03/20/2026 Honolulu HI Broadcast Media
Home on Kaiahulo drive in Mokuleia was swept
onto the beach due to flash flooding.
Remnants of the house appear to be split in
half, and parts of the house appear to have
collapsed.
&&Flash Flood, Honolulu
- When
- March 20, 10:00 PM HST to March 21, 12:00 PM HST
- Where
- Honolulu County, 6.72 mi NNE of Kawela Bay to 11.55 mi W of Mokuleia
- Cause
- Heavy Rain
- Injuries
- 0 direct, 10 indirect
- Property damage
- $1.0 billion
- Crop damage
- $10 million
- Reported by
- NWS Employee
- Coordinates
- 21.781, -157.963
At approximately 800 pm HST, a mesoscale convective system was observed moving over the Kauai Channel towards Oahu. At around 900 pm HST, this mesoscale convective system moved over the west side of Oahu, then the Northern half of Oahu, and began to deliver large amounts of heavy rain. Due to the slow moving nature of this weather system, enormous rain amounts accumulated in a very short time frame. At approximately 1000 pm HST, stream levels rose above flood thresholds and reservoirs filled up. From 1100 pm HST to 200 AM HST, a massive flood wave surged through the North Shore. Multiple roads became impassable across Northern Oahu, Haleiwa became completely cut off, and multiple homes and many cars got swept away in flood waters. Many homes and cars that were not washed away were heavily damaged beyond use or habitation. Businesses were also flooded, and an ambulance was reportedly lost due to the rising flood waters. With the help of police officers, the crew escaped the ambulance through the side window. There were over 200 rescues by first responders and residents, these rescues included rescues from police, fire, national guard, and lifeguards. 10 people were taken to the ER with non critical hypothermia due to prolonged exposure to the flood waters. Much of the destruction and rescues were reported in Waialua and Haleiwa. However the damage spread to the northeast section of Oahu where multiple homes were inundated with flood waters. Over 171 million dollars in damages were reported across Oahu's public schools from the Department of Education and officials put the total costs of the storm island wide above 1 billion dollars .
Flash Flood, Maui
- When
- March 21, 6:00 AM HST to March 22, 6:00 PM HST
- Where
- Maui County, 2.1 mi N of Honokohau to 1.34 mi WNW of Honokahua
- Cause
- Heavy Rain
- Property damage
- $100,000
- Reported by
- Emergency Manager
- Coordinates
- 21.050, -156.620
Early in the morning of March 22nd, heavy rain moved over Maui and led to flooding across the island. Many roads were flooded and landslides were reported. Keawe St. was closed in both directions between Kupuohi St. and Kuhua St. due to flooding. Both lanes of Honoapiilani Highway were blocked near mile marker 33 due to a landslide. Kahekili Highway was closed from 2120 Kahekili Highway to Kahakuloa due to flooding. Kapunakea St. and Front St. intersection was closed due to flooding. Kahekili Highway was closed from 2120 Kahekili Hwy to Kahakuloa due to flooding. Hana Highway/Hanakai St. to Hanakai Alamaha St. was closed due to flooding. Many other roads across Maui were closed due to the flooding.
Flash Flood, Maui
- When
- March 21, 10:00 AM HST to March 22, 10:00 AM HST
- Where
- Maui County, 3.22 mi NNW of Ilio Point to 8.82 mi SW of Papohaku Beach Park
- Cause
- Heavy Rain
- Property damage
- $10 million
- Reported by
- Emergency Manager
- Coordinates
- 21.265, -157.284
Heavy rain moved over Molokai and led to numerous impacts. A landslide closed road from mile marker 7 to 12 at Kamehameha V Highway with flood water, mud, and boulders up to 4 feet deep. Kamehameha V Highway was then closed from Kapaakea Loop eastward due to flooding. On March 22 early in the morning, homes and vehicles in the Kalamaula Homesteads became flooded from heavy rain and thunderstorms. Residents also reported leaking roofs and lost goods, appliances, and other property damages.
Heavy Rain, Maui
- When
- March 21, 12:00 PM HST to 3:00 PM HST
- Where
- Maui County, 8.99 mi W of Shipwreck Beach to 3.07 mi E of Manele Harbor
- Reported by
- Broadcast Media
- Coordinates
- 20.904, -157.058
Hawaii News Now posted a video received from the public of gushing water along hillsides and roads on Lanai. HNN also reported water on Manele Rd between mile marker 8 and mile marker 9.
Flash Flood, Honolulu
- When
- March 23, 12:00 PM HST to 6:00 PM HST
- Where
- Honolulu County, 0.83 mi WNW of Kahuku to 5.3 mi E of Kawailoa
- Cause
- Heavy Rain
- Property damage
- $10 million
- Reported by
- NWS Employee
- Coordinates
- 21.685, -157.962
Heavy rain fell over the Koolau mountain range in the middle to later half of the morning, then a thunderstorm developed and anchored itself over the mountains. This thunderstorm then produced a large amount of rain in a short time frame, quickly overwhelming Manoa Stream and sending a flood surge down towards Manoa Valley. Manoa marketplace had nearly 2 feet of water and parked cars were inundated. Homes in Manoa reported flooding and an excavation site quickly became overwhelmed with water and sent mud and debris down the road. The overflowing Manoa and Palolo Streams inundated the entire campus of Hokulani Elementary School in St. Louis Heights and students were evacuated. Large boulders and debris were observed across many roads in Manoa Valley and flooding was also observed across the upper portion of the University of Hawaii at Manoa campus. A home was also flooded in Laie.
Flash Flood, Hawaii
- When
- March 23, 12:00 PM HST to 7:00 PM HST
- Where
- Hawaii County, 4.65 mi NE of Hilo to 8.61 mi NE of Hawaiian Ocean Vw Est
- Cause
- Heavy Rain
- Property damage
- $2.0 million
- Reported by
- Emergency Manager
- Coordinates
- 19.776, -155.018
Heavy rain developed over the eastern and southeastern areas of the Big Island, leading to flooding impacts. Flooding was reported along Bayfront Highway and on Highway 11 south of Hilo. Flooding was also reported in Keeau Industrial Park. A residence in Pahala reportedly experienced flooding.
- Flash Flood
- Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.
- Heavy Rain
- Rainfall totals unusual for the place and season that did not produce a flood.
After NWS Directive 10-1605, the rules offices file Storm Data by.
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: 1317872, 1317876, 1318322, 1320397, 1317873, 1319369.