High Surf in Hawaii, June 20 to 21, 2021

Name: High Surf in Hawaii, June 20 to 21, 2021
Start: 2021-06-20T12:00
End: 2021-06-21T15:00
Location: Hawaii

June 20 to 21, 2021 · NWS HFO · 18 events in 18 counties and zones

A swell from the southern hemisphere generated surf of 6 to 12 feet along the south-facing shores of all the Hawaiian Islands. No significant property damage or injuries were reported.

Where it happened

Every event with a place to put it; 18 filed by county or forecast zone are drawn at its center, in a lighter ring. 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

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 18

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.

What happened

The episode as NWS HFO wrote it up.

A swell from the southern hemisphere generated surf of 6 to 12 feet along the south-facing shores of all the Hawaiian Islands. No significant property damage or injuries were reported.

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 Jun 20, 9:39 AM HST, 2 hours 21 minutes earlier.

Area forecast discussion, Jun 20, 9:39 AM HST, 2 hours 21 minutes before

Area Forecast Discussion...CORRECTED
National Weather Service Honolulu HI
939 AM HST Sun Jun 20 2021

.SYNOPSIS...
Gentle to moderate trade winds will remain in place for the next
few days, then decline around midweek as the surface ridge north
of the state weakens. Showers will remain focused along windward
slopes, though a lingering disturbance aloft will produce clouds
and spotty showers over sheltered leeward areas this afternoon.
Stable and drier conditions are expected by Monday.

&&

.DISCUSSION...
A slightly unstable trade wind flow continues. A surface ridge
roughly 700 miles north of Kauai is driving the moderate trade
winds. A weak and compact upper level low centered roughly 375
miles northeast of the islands is drifting away, but a trailing
upper level trough running over Oahu is leaving some instability.
Moisture in the trade wind flow is around seasonal normal and will
deliver showers to windward slopes. The slightly unstable trade
winds are weak enough for sea breezes to develop across sheltered
leeward areas, where clouds and a few showers will briefly develop
this afternoon. These showers may linger into the evening along
the Kona coast of the Big Island.

Trades will hold at gentle to moderate strength Monday and
Tuesday, then ease on Wednesday and Thursday as the surface ridge
to the north weakens and is pushed closer to the state. Expect
leeward sea breezes to become more widespread as the trades ease.
However, the atmosphere will become increasingly stable by Monday
as the upper level trough is displaced by an upper level ridge
building in from the east. This points to limited windward showers
and dry conditions leeward. The exception will be typical
summertime clouds and showers over the Kona slopes of the Big
Island each afternoon and evening.

&&

.AVIATION...
High pressure northeast of the state will keep light to moderate
easterly trade winds in place through tonight. Some localized
land breezes and sea breezes will be possible in the more
sheltered leeward areas as well. However, most shower activity
will favor windward slopes and coasts, especially during the
overnight and early morning hours. VFR conditions are expected to
prevail with only temporary MVFR ceilings and visibility in any
heavier showers that occur. Shower activity is expected to wane on
Monday compared to the previous couple of days as two upper level
lows near the islands drift farther away from the state.

There are currently no AIRMETs in effect.

&&

.MARINE...
Light to moderate trade winds are expected to persist well into
the new week as a surface high remains far northeast of the
islands. The associated surface ridge will slowly move south
through the week to a position just outside the northern offshore
waters. Therefore, trades will be trending down to mainly light
by Thursday. The ridge is expected to shift back north on Friday,
allowing trades to increase again.

The current south swell is forecast to peak today before gradually
subsiding through Monday. With the current buoy data, surf along
south facing shores is slated to be just below the high surf
advisory criteria of 8 feet for today, but we will be monitoring
the situation closely. Smaller swells will keep surf from going
flat through the upcoming week. A few small northwest swells will
move through this week. East shore surf will decline a bit later
in the week as trades weaken, but get another boost Friday into
the weekend as trades pick back up.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

DISCUSSION...Wroe
AVIATION...Vaughan
MARINE...TS

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

18 high surf. Local standard time, as filed.

High Surf, Niihau

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Niihau forecast zone
Reported by: Trained Spotter
Coordinates: 22.011, -159.705 (the zone’s center; the record gives no point)

High Surf, Kauai Southwest

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Kauai Southwest forecast zone
Reported by: Trained Spotter
Coordinates: 22.011, -159.705 (the zone’s center; the record gives no point)

High Surf, Waianae Coast

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Waianae Coast forecast zone
Reported by: Trained Spotter
Coordinates: 21.455, -157.961 (the zone’s center; the record gives no point)

High Surf, Kahoolawe

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Kahoolawe forecast zone
Reported by: Trained Spotter
Coordinates: 21.027, -156.788 (the zone’s center; the record gives no point)

High Surf, Maui Leeward West

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Maui Leeward West forecast zone
Reported by: Trained Spotter
Coordinates: 21.027, -156.788 (the zone’s center; the record gives no point)

High Surf, Kona

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Kona forecast zone
Reported by: Trained Spotter
Coordinates: 19.602, -155.523 (the zone’s center; the record gives no point)

High Surf, Kauai South

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Kauai South forecast zone
Reported by: Trained Spotter
Coordinates: 22.011, -159.705 (the zone’s center; the record gives no point)

High Surf, East Honolulu

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: East Honolulu forecast zone
Reported by: Trained Spotter
Coordinates: 21.455, -157.961 (the zone’s center; the record gives no point)

High Surf, Honolulu Metro

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Honolulu Metro forecast zone
Reported by: Trained Spotter
Coordinates: 21.455, -157.961 (the zone’s center; the record gives no point)

High Surf, Ewa Plain

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Ewa Plain forecast zone
Reported by: Trained Spotter
Coordinates: 21.455, -157.961 (the zone’s center; the record gives no point)

High Surf, Molokai Leeward South

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Molokai Leeward South forecast zone
Reported by: Trained Spotter
Coordinates: 21.027, -156.788 (the zone’s center; the record gives no point)

High Surf, Lanai Leeward

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Lanai Leeward forecast zone
Reported by: Trained Spotter
Coordinates: 21.027, -156.788 (the zone’s center; the record gives no point)

High Surf, Lanai South

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Lanai South forecast zone
Reported by: Trained Spotter
Coordinates: 21.027, -156.788 (the zone’s center; the record gives no point)

High Surf, Maui Central Valley South

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Maui Central Valley South forecast zone
Reported by: Trained Spotter
Coordinates: 21.027, -156.788 (the zone’s center; the record gives no point)

High Surf, South Maui/Upcountry

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: South Maui/Upcountry forecast zone
Reported by: Trained Spotter
Coordinates: 21.027, -156.788 (the zone’s center; the record gives no point)

High Surf, South Haleakala

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: South Haleakala forecast zone
Reported by: Trained Spotter
Coordinates: 19.602, -155.523 (the zone’s center; the record gives no point)

High Surf, Big Island South

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Big Island South forecast zone
Reported by: Trained Spotter
Coordinates: 19.602, -155.523 (the zone’s center; the record gives no point)

High Surf, Big Island Southeast

When: June 20, 12:00 PM HST to June 21, 3:00 PM HST
Where: Big Island Southeast forecast zone
Reported by: Trained Spotter
Coordinates: 19.602, -155.523 (the zone’s center; the record gives no point)

What these are

High Surf: Large waves breaking on the shore that caused damage, erosion or casualties.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Hawaii in 2021 Every state in 2021 This day in weather history Warnings in Hawaii, June 2021

Sources

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: 958286, 958287, 958288, 958289, 958290, 958291, 958292, 958293, 958294, 958295, 958296, 958297, 958298, 958299, 958300, 958301, 958302, 958303.