Alert archive / California / Frost Advisories in 2026

Frost Advisory 14, NWS Eureka, CA

April 16, 2026Del Norte County, Humboldt County, Mendocino County, California

NWS Eureka, CA issued this frost advisory at Apr 16, 2026, 12:49 PM PDT for Del Norte County, Humboldt County, Mendocino County, California. It took effect at Apr 17, 2026, 2:00 AM PDT. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued
Apr 16, 2026, 12:49 PM PDT (19:49 UTC)
In effect from
Apr 17, 2026, 2:00 AM PDT
Expired
Apr 17, 2026, 9:00 AM PDT
In force
7 hr
Issued by
NWS Eureka, CA

Counties Del Norte County, CA, Humboldt County, CA, Mendocino County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 47 km from the middle of the area, began a volume at 19:51 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

Oakland, CA (KOAK), launched 12:00Z, 7.8 hours before the alert went out and 349 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, Oakland, CA at 12:00Z on 2026-04-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Oakland, CA at 12:00Z on 2026-04-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -22 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
776 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
-22 m²/s²
0-3 km storm-relative helicity
19 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

779 
WWUS76 KEKA 161949
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
1249 PM PDT Thu Apr 16 2026

CAZ102-105-106-108-110-111-114-116>118-170400-
/O.NEW.KEKA.FZ.W.0003.260417T0900Z-260417T1600Z/
Interior Del Norte-Northeastern Interior Humboldt-Southeastern
Interior Humboldt-Southern Trinity-Northwestern Interior
Mendocino-Northeastern Interior Mendocino-Northern Lake-
Northwestern and Central Trinity-Northeastern Trinity-Western
Lake-
Including Covelo, Hayfork, Peanut, Gravelly Valley Airport, Hoopa,
Willow Creek, Willits, Hyampom, Dinsmore, Potter Valley, and Forest
Glen
1249 PM PDT Thu Apr 16 2026

...FREEZE WARNING IN EFFECT FROM 2 AM TO 9 AM PDT FRIDAY...

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

* WHERE...Humboldt Interior, Northern Mendocino Interior, Interior
  Del Norte, Southern Trinity, Northern Lake, Northwestern and
  Central Trinity, Northeastern Trinity, and Western Lake.

* WHEN...From 2 AM to 9 AM PDT 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.

&&

$$

CAZ101-103-104-109-112-113-170400-
/O.NEW.KEKA.FR.Y.0014.260417T0900Z-260417T1600Z/
Coastal Del Norte-Northern Coastal Humboldt-Southwestern Humboldt-
Coastal Mendocino-Southwestern Interior Mendocino-Southeastern
Interior Mendocino-
Including Philo, Ukiah, Fernbridge, Ettersburg, Hopland, Trinidad,
Comptche, Honeydew, Calpella, Ft Dick, Arcata, Whitethorn,
McKinleyville, Eureka, Boonville, Fieldbrook, Briceland, Talmage,
Fortuna, and Redwood Valley
1249 PM PDT Thu Apr 16 2026

...FROST ADVISORY IN EFFECT FROM 2 AM TO 9 AM PDT FRIDAY...

* WHAT...Temperatures as low as 34 will result in frost formation.

* WHERE...Del Norte, Humboldt, and Mendocino Coast, and Southern
  Mendocino Interior.

* WHEN...From 2 AM to 9 AM PDT 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 hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

MKK
3 follow-up statements
291 
WWUS76 KEKA 170346
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
846 PM PDT Thu Apr 16 2026

CAZ102-105-106-108-110-111-114-116>118-171200-
/O.CON.KEKA.FZ.W.0003.260417T0900Z-260417T1600Z/
Interior Del Norte-Northeastern Interior Humboldt-Southeastern
Interior Humboldt-Southern Trinity-Northwestern Interior
Mendocino-Northeastern Interior Mendocino-Northern Lake-
Northwestern and Central Trinity-Northeastern Trinity-Western
Lake-
Including Peanut, Potter Valley, Willow Creek, Willits, Dinsmore,
Gravelly Valley Airport, Covelo, Hayfork, Hyampom, Hoopa, and Forest
Glen
846 PM PDT Thu Apr 16 2026

...FREEZE WARNING REMAINS IN EFFECT FROM 2 AM TO 9 AM PDT FRIDAY...

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

* WHERE...Humboldt Interior, Northern Mendocino Interior, Interior
  Del Norte, Southern Trinity, Northern Lake, Northwestern and
  Central Trinity, Northeastern Trinity, and Western Lake.

* WHEN...From 2 AM to 9 AM PDT 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.

&&

$$

CAZ101-103-104-109-112-113-171200-
/O.CON.KEKA.FR.Y.0014.260417T0900Z-260417T1600Z/
Coastal Del Norte-Northern Coastal Humboldt-Southwestern Humboldt-
Coastal Mendocino-Southwestern Interior Mendocino-Southeastern
Interior Mendocino-
Including Philo, Fernbridge, Fortuna, Comptche, Honeydew, Whitethorn,
Talmage, Hopland, Ukiah, Fieldbrook, Arcata, Boonville,
McKinleyville, Ettersburg, Trinidad, Eureka, Briceland, Ft Dick,
Calpella, and Redwood Valley
846 PM PDT Thu Apr 16 2026

...FROST ADVISORY REMAINS IN EFFECT FROM 2 AM TO 9 AM PDT FRIDAY...

* WHAT...Temperatures as low as 33 could result in frost formation.

* WHERE...Del Norte, Humboldt, and Mendocino Coast, and Southern
  Mendocino Interior.

* WHEN...From 2 AM to 9 AM PDT 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 hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

DS
384 
WWUS76 KEKA 171211
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
511 AM PDT Fri Apr 17 2026

CAZ102-105-106-108-110-111-114-116>118-171600-
/O.CON.KEKA.FZ.W.0003.000000T0000Z-260417T1600Z/
Interior Del Norte-Northeastern Interior Humboldt-Southeastern
Interior Humboldt-Southern Trinity-Northwestern Interior
Mendocino-Northeastern Interior Mendocino-Northern Lake-
Northwestern and Central Trinity-Northeastern Trinity-Western
Lake-
Including Forest Glen, Hayfork, Willits, Covelo, Hyampom, Dinsmore,
Hoopa, Potter Valley, Peanut, Willow Creek, and Gravelly Valley
Airport
511 AM PDT Fri Apr 17 2026

...FREEZE WARNING REMAINS IN EFFECT UNTIL 9 AM PDT THIS MORNING...

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

* WHERE...Humboldt Interior, Northern Mendocino Interior, Interior
  Del Norte, Southern Trinity, Northern Lake, Northwestern and
  Central Trinity, Northeastern Trinity, and Western Lake.

* WHEN...Until 9 AM PDT 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.

&&

$$

CAZ101-103-104-109-112-113-171600-
/O.CON.KEKA.FR.Y.0014.000000T0000Z-260417T1600Z/
Coastal Del Norte-Northern Coastal Humboldt-Southwestern Humboldt-
Coastal Mendocino-Southwestern Interior Mendocino-Southeastern
Interior Mendocino-
Including Ft Dick, Honeydew, Whitethorn, Arcata, Philo, Comptche,
Redwood Valley, Calpella, Trinidad, Hopland, Ukiah, Talmage,
Fernbridge, Fieldbrook, Ettersburg, Briceland, Boonville, Eureka,
Fortuna, and McKinleyville
511 AM PDT Fri Apr 17 2026

...FROST ADVISORY REMAINS IN EFFECT UNTIL 9 AM PDT THIS MORNING...

* WHAT...Temperatures as low as 33 could result in frost formation.

* WHERE...Del Norte, Humboldt, and Mendocino Coast, and Southern
  Mendocino Interior.

* WHEN...Until 9 AM PDT 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 hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

EYS
952 
WWUS76 KEKA 171600
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
900 AM PDT Fri Apr 17 2026

CAZ102-105-106-108-110-111-114-116>118-171700-
/O.EXP.KEKA.FZ.W.0003.000000T0000Z-260417T1600Z/
Interior Del Norte-Northeastern Interior Humboldt-Southeastern
Interior Humboldt-Southern Trinity-Northwestern Interior
Mendocino-Northeastern Interior Mendocino-Northern Lake-
Northwestern and Central Trinity-Northeastern Trinity-Western
Lake-
Including Potter Valley, Willits, Forest Glen, Hyampom, Peanut,
Gravelly Valley Airport, Covelo, Hoopa, Dinsmore, Hayfork, and Willow
Creek
900 AM PDT Fri Apr 17 2026

...FREEZE WARNING HAS EXPIRED...

$$

CAZ101-103-104-109-112-113-171700-
/O.EXP.KEKA.FR.Y.0014.000000T0000Z-260417T1600Z/
Coastal Del Norte-Northern Coastal Humboldt-Southwestern Humboldt-
Coastal Mendocino-Southwestern Interior Mendocino-Southeastern
Interior Mendocino-
Including Whitethorn, McKinleyville, Hopland, Comptche, Talmage, Ft
Dick, Fortuna, Trinidad, Arcata, Fernbridge, Boonville, Calpella,
Eureka, Fieldbrook, Ukiah, Ettersburg, Honeydew, Briceland, Philo,
and Redwood Valley
900 AM PDT Fri Apr 17 2026

...FROST ADVISORY HAS EXPIRED...

$$

For hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

MKK

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 Eureka, CA wrote its last area forecast discussion before this frost advisory went out at Apr 16, 1:30 AM PDT, 11 hours 19 minutes earlier.

Area forecast discussion, Apr 16, 1:30 AM PDT, 11 hours 19 minutes before
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
130 AM PDT Thu Apr 16 2026

.SYNOPSIS...Near freezing to freezing low temperatures expected
to return late week. Breezy winds forecasted for Lake County
through the end of the week. More rain expected late weekend into
next week.

&&

.DISCUSSION...Generally, rain has ended for NW CA. This frontal
system will now force northerly winds throughout the region as the
front moves southeasterly and cold air fills into the area. In
general, coastal areas and higher terrain locations will be gustier.
Through Thursday morning and especially in the afternoon, strong
northerlies will develop in Lake County for the higher terrain areas
in the eastern and southern portions of the county.

Due to this frontal passage, much colder and drier air will advect
over the region. In response, snow levels drop down to ~1,500ft for
Trinity Co. and ~2,000ft for Humboldt Co. This drop did not create
much snow for areas outside of the mountains in northern Trinity Co.
However, this colder air will increase the likelihood for
frost/freeze conditions for the entire area overnight through the
week. Observations show temperatures plummeting due to lack of
insulating cloud coverage for the interior areas. NBM data shows the
interior valleys are forecasted to get colder than 30F Thursday and
Friday mornings. As growing season begins, it is recommended to
cover sensitive plants and take other precautions to protect
agricultural property these mornings. Thursday morning, Freeze
Warnings have been issued for some of the coldest interior valleys,
along with Frost Advisories for most coastal areas.

The GFS and ECMWF are both signaling for another frontal storm
arriving this weekend. The GFS ensemble shows light rain Sunday with
heavier rain possible on Monday. The EPS shows almost the same, with
rain beginning on Saturday evening. What these models also show is
more widespread rainfall over the area with precipitation
accumulations up to 0.75" at lake level in Lake county and
in the valleys of southern Mendocino counties. JLW&DS

&&

.AVIATION...Robust N-NE winds 1000 to 2000 feet AGL will develop
tonight into early Thursday morning in the wake of a cold front.
Low level wind shear and shallow turbulence are expected, especially
around KUKI by 08Z. Gusty northerly winds are forecast to quickly
mix down during the morning hours on Thursday at coastal aerodromes.
Peak wind gusts around 30 kt are forecast by afternoon at both KACV
and KCEC. Turbulent and rough conditions are probable for small and
light weight aircraft. Otherwise, strong subsidence in the wake of a
cold front has been resulting in clearing skies Wednesday night. VFR
is expected to continue to prevail through the day on Thursday at
all forecast terminals.

&&

.MARINE...Vigorous cold front has been producing gusty northerly
winds Wednesday evening. Wind gusts were close to gale at buoy #14
NW of Pt Arena with gusts to 33 kt. Elsewhere, northerlies have been
sub-gale, gusting to 22-30 kt. Seas have also built to hazardous
levels for small vessels, 8 to 9 ft at 8 to 9 seconds. Therefore,
the advisories for small craft are on the mark for the remainder of
tonight. High resolution mesoscale models, GFS and NBM all indicate
northerly winds increasing to gales for mostly the southern waters
on Thu. GFS and NBM also indicate gale gusts developing in the
afternoon for the northern waters. Thus, a gale warning has been
hoisted for the northern outer waters for gusts to 35 kt and steep
waves around 11 feet at 8-10 seconds. Steep waves will also continue
to build through the day on Thursday and peak Thursday night. Max
significant wave heights are projected to hit 13 feet in the
southern waters and 11 feet in the northern waters. On Friday,
elevated seas will steadily subside through the day as winds
diminish below gale. By Saturday, a lighter wind regime is forecast
as an offshore frontal system breaks down the offshore ridge.
Moderate southerly breezes are forecast to develop in advance of the
front Sat night into Sunday. Borderline advisory level winds will be
possible (40% chance) with gusts over 22 kt on Sunday.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Frost Advisory until 9 AM PDT this morning for CAZ101-103-
     104-109-112.

     Freeze Warning until 9 AM PDT this morning for CAZ102-
     105>108-110-111-113>115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 5 AM PDT Friday for PZZ450.

     Small Craft Advisory until 1 PM PDT this afternoon for
     PZZ455.

     Gale Warning from 1 PM this afternoon to 5 AM PDT Friday
     for PZZ455.

     Small Craft Advisory until 4 PM PDT this afternoon for
     PZZ470.

     Gale Warning from 4 PM this afternoon to 5 AM PDT Friday
     for PZZ470.

     Small Craft Advisory until 5 AM PDT early this morning for
     PZZ475.

     Gale Warning from 5 AM early this morning to 5 AM PDT
     Friday for PZZ475.

&&

NOTE: The full forecast discussion is now regularly issued between
10 am/pm and 1 pm/am. Additional updates will be issued as needed.

Visit us at https://www.weather.gov/eureka

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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png

The office that day

Everything else NWS Eureka, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 16, 3:08 AM PDTFrost AdvisoryEKADel Norte, Humboldt, Mendocino10 hr
Apr 16, 3:08 AM PDTFreeze WarningEKADel Norte, Humboldt, Lake, Mendocino, Trinity10 hr
Apr 16, 12:49 PM PDTFreeze WarningEKADel Norte, Humboldt, Lake, Mendocino, Trinity20 hr

Nearby

Frost Advisories in California, 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.