933
FXUS66 KSEW 120239
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
739 PM PDT Thu Jun 11 2026
.SYNOPSIS...
The latest forecast remains on track this evening. Dry weather
will persist this weekend into next week as an upper level ridge
builds over a thermal trough this weekend. Temperatures remain
on track to increase over the weekend into early next week into
the 80s and 90s across the region, with much of the lowlands
seeing moderate HeatRisk and a few isolated areas of major
HeatRisk. The dry and unstable airmass will also produce
elevated fire weather concerns. Onshore flow returns Monday
night into Tuesday, with breezy winds bringing in cooler air.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
Upper level pattern remains the same, continuing to show that ridge
beginning to set up over Western Washington on Friday, bringing max
temperatures between 70 and 75 degrees along with it. On
Saturday, expect localized moderate HeatRisk, with temperatures
between 75 and 85 degrees at the hottest point of the day.
Cloud cover will continue to be minimal over the Western
Washington region. Widespread cloud coverage has located off
the coast, with low clouds forming during the mornings over the
Cascade and Olympic Mountains, eventually dissipating as the
weekend days drag on.
HPR/NW
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
The upper level ridge will continue to build over the thermal trough
Sunday into Monday, which will produce an offshore pattern where
temperatures will climb, and relative humidities will decrease. See
fire weather discussion below for details on elevated fire weather
concerns. The other concern is heat, with high temperatures
remaining on track to peak Sunday into Monday. Given the
persistent forecast in high confidence for widespread moderate
HeatRisk Sunday/Monday, and pockets of isolated major HeatRisk
in the Seattle metro and south/southwest interior, a heat
advisory was issued, which will go into effect at 11 AM Sunday
through 5 AM Tuesday. The warmest period will be from Sunday
into Monday night. High temperatures will reach from the mid 80s
into the upper 90s, with the warmest temperatures in the south
sound/southwest interior. Overnight temperatures in the upper
50s/low to mid 60s also may not allow for homes to cool off
substantially overnight from daytime heat. Additionally, water
temperatures during this heat event remain chilly, with most
lakes and rivers hovering in the 50s and 60s. Even with the warm
air temperatures, the cold waters can result in cold shock for
prolonged time spent in the water. Take precautions if spending
time near the water, or if spending time outdoors early next
week.
The pattern remains on track to shift towards an onshore pattern
late Monday night into Tuesday, as ensembles have the ridge weaken
and shift eastward. Onshore flow will increase as early as Monday
night, persisting into Tuesday and through the week.
There will be a few breezy areas, particularly the southwest
interior, the Strait of Juan de Fuca coast, and along the Cascade
Crest, where there is potential for winds up to 25-35 mph Tuesday
into Wednesday morning. The onshore winds will be slow to bring
temperatures down initially, with highs in the interior Tuesday
still ranging from the mid 70s into the mid 80s. The immediate
Pacific Coast will see the first of the relief from the heat, with
the spread of cooler air moving further inland on Wednesday and
Thursday, with highs in the interior dropping into the 70s. Moisture
remains virtually nonexistent during the period, although
overnight diurnal pushes will bring in some cloud coverage. The
chance of showers remains slim, with only a 20% chance of them
in the Cascades and Olympics Wednesday and Thursday.
HPR
&&
.AVIATION...
VFR this evening under northwest flow aloft, with northwest
winds around 5-10 kt. Probability for low ceilings tonight
remain highest along the Pacific Coast, with a 50-70% chance of
MVFR, and a 40-60% chance of IFR along the coast. Some patchy
fog can`t be ruled out either in these areas. The timeframe for
low ceiling development is from 12Z to just before 18Z, before
clearing to VFR. Winds overnight into Friday shift to the
northeast around 5 kt or less, then back to the northwest 5-10
kt.
KSEA...VFR likely to persist through the TAF period. Winds NW
this evening 5-10 kt, switching to the northeast 5 kt or less
overnight, then back to the north/northwest 5-10 kt Friday
afternoon.
HPR/15
&&
.MARINE...
High pressure will build over the coastal waters through the end
of the week. This will keep the pattern onshore for the next
couple of days, with a push expected to produce winds up to 25
kt in the Strait of Juan de Fuca this afternoon/evening. A small
craft advisory continues for central and east sections through
tonight. The ridge axis will move close to the coast over the
weekend, with a thermal trough also building up the coast. This
will result in periods of offshore flow to northerly flow from
Saturday through Monday. The likelihood of winds exceeding 20 kt
during this period remain low, but the outer coastal waters may
see north winds approach 20 kt Friday afternoon, and Puget
Sound waters approach 15 kt Saturday afternoon. The ridge will
weaken and move east, and onshore flow will return Monday night
through midweek. There is potential for winds exceeding 20 kt in
the coastal waters late Monday through midweek, as well as a
potential for gale gusts in the Strait of Juan de Fuca Tuesday.
Seas through Monday will hover around 4-6 ft, and increase to
6-8 ft through midweek, with potential for seas 8-11 ft in the
outer coastal waters next week.
HPR
&&
.FIRE WEATHER...
An upper level ridge offshore will move to the coastline
Saturday through Monday. A thermal trough will build under the
ridge, creating a dry, warm, and unstable airmass across the
region. While recent rains helped fuels from reaching critical
red flag criteria going into the weekend, elevated fire concerns
will remain for dry grassy/shrubby areas, as well as piles of
dead fuels. Highs in the 80s to 90s, combined with northeast
winds coming down the Cascades/Olympics, will result in relative
humidity values as low as 15-20%, particularly in the south
interior, and in valleys of the Cascades where temperatures will
be hottest. A few gusts up to 20 mph in the central interior and
the Cascade crest from the north/northeast will be possible over
the weekend during the morning/afternoon periods. While relative
humidities will improve with the return of onshore flow Tuesday,
winds will become particularly gusty, with portions of the
coast/mountains/south interior seeing west to northwest winds
gusting up to 25 to 35 mph.
HPR
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory from 11 AM Sunday to 5 AM PDT Tuesday for City
of Seattle-Downtown Everett / Marysville Area-Eastern
Kitsap County-Eastern Strait of Juan de Fuca-Eastside-
Foothills and Valleys of Central King County-Foothills
and Valleys of Pierce and Southern King Counties-
Foothills and Valleys of Snohomish and Northern King
Counties-Foothills and Valleys of Thurston and Lewis
Counties-Foothills and Valleys of the North Cascades-
Foothills of the Western and Southern Olympic Peninsula-
Island County-Lake Crescent Area Including US 101-Lower
Chehalis River Valley-Lowlands of Lewis and Southern
Thurston Counties-Lowlands of Pierce and Southern King
Counties-Lowlands of Western Skagit and Northwestern
Snohomish Counties-Lowlands of Western Whatcom County-
Middle Chehalis River Valley-Northern Hood Canal-Olympia
and Southern Puget Sound-Port Townsend Area-San Juan
County-Shoreline / Lynnwood / South Everett Area-Southern
Hood Canal-Willapa and Black Hills.
PZ...Small Craft Advisory until 1 AM PDT Friday for Central U.S.
Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
Strait Of Juan De Fuca.
&&
$$
NWS SEW Office Area Forecast Discussion