Seattle Boeing Field, Washington climate: Climate normals at a NOAA weather station
Seattle Boeing Field's normal year runs from 36°F December nights to 77°F August afternoons, with 36.5 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.1°C, December lows of 2°C, August highs of 25°C, 927 mm of precipitation a year.
- NOAA stationSeattle Boeing Field
- Station IDUSW00024234
- Location47.53°N 122.30°W
- Elevation20 ft (6 m)
On October 23, the normal high in Seattle Boeing Field is 59°F and the normal low 45°F, and the chance of measurable rain or snow is 52%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Seattle Boeing Field.
- Jan 49° 37°
- Feb 51° 37°
- Mar 55° 39°
- Apr 60° 44°
- May 67° 49°
- Jun 71° 54°
- Jul 77° 58°
- Aug 77° 58°
- Sep 72° 54°
- Oct 61° 46°
- Nov 53° 40°
- Dec 48° 36°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Seattle Boeing Field each month?
August is the warmest month, with normal highs of 77°F; December the coldest, with normal lows of 36°F. The most precipitation falls in November (5.80 in), the least in July (0.56 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 49°F | 37°F | 42.7°F | 5.21 | 19 | <1 | 7 | 8 h 50 min |
| February | 51°F | 37°F | 43.7°F | 3.71 | 16 | <1 | 7 | 10 h 10 min |
| March | 55°F | 39°F | 47.1°F | 3.94 | 18 | <1 | 3 | 11 h 50 min |
| April | 60°F | 44°F | 51.7°F | 2.89 | 15 | <1 | <1 | 13 h 30 min |
| May | 67°F | 49°F | 57.9°F | 1.98 | 11 | <1 | <1 | 15 h |
| June | 71°F | 54°F | 62.6°F | 1.22 | 9 | 1 | <1 | 16 h |
| July | 77°F | 58°F | 67.4°F | 0.56 | 3 | 2 | <1 | 15 h 40 min |
| August | 77°F | 58°F | 67.8°F | 0.83 | 4 | 1 | <1 | 14 h 20 min |
| September | 72°F | 54°F | 62.8°F | 1.37 | 9 | <1 | <1 | 12 h 40 min |
| October | 61°F | 46°F | 53.7°F | 3.49 | 15 | <1 | <1 | 11 h |
| November | 53°F | 40°F | 46.4°F | 5.80 | 18 | <1 | 4 | 9 h 20 min |
| December | 48°F | 36°F | 42.0°F | 5.49 | 18 | <1 | 8 | 8 h 30 min |
| Year (annual) | 62°F | 46°F | 53.8°F | 36.49 | 154 | 3 | 30 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 9°C | 3°C | 5.9°C | 132 mm |
| February | 10°C | 3°C | 6.5°C | 94 mm |
| March | 13°C | 4°C | 8.4°C | 100 mm |
| April | 15°C | 6°C | 10.9°C | 73 mm |
| May | 19°C | 10°C | 14.4°C | 50 mm |
| June | 22°C | 12°C | 17.0°C | 31 mm |
| July | 25°C | 14°C | 19.7°C | 14 mm |
| August | 25°C | 15°C | 19.9°C | 21 mm |
| September | 22°C | 12°C | 17.1°C | 35 mm |
| October | 16°C | 8°C | 12.1°C | 89 mm |
| November | 12°C | 4°C | 8.0°C | 147 mm |
| December | 9°C | 2°C | 5.6°C | 139 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Seattle (6 miles away), gets 6 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024234; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
Which months are mildest at Seattle Boeing Field?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, July has the fewest days with rain (3).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024234.
When is the last frost at Seattle Boeing Field?
In Seattle Boeing Field, the last spring frost (32°F) comes after March 13 in half of years and after April 1 in one year in ten; the first autumn frost comes before November 17 in half of years and before November 1 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- March 131 year in 10 after April 1; 9 in 10 after February 20
- First autumn frost, half of years before
- November 171 year in 10 before November 1; 9 in 10 before December 6
NOAA puts the median frost-free season at 247 days, and the season without a hard freeze (28°F) at 295 days.
A hard freeze (28°F) comes after February 18 in half of springs and before December 2 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Seattle Boeing Field in zone 9a in ZIP code 98108, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 9a: the coldest night of a typical year reaches 21°F (22 complete years).
Frost dates for every NOAA station in Washington · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00024234; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get at Seattle Boeing Field?
In a normal year in Seattle Boeing Field, 3 days a year reach 90°F, 30 nights fall to 32°F or colder and 154 days bring measurable precipitation.
- Days at 90°F or more
- 3a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 30a normal year
- Days that stay below freezing
- 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 154a normal year
The highest temperature in this station's record (since 1948) is 105°F, on July 29, 2009; the lowest is 3°F, on January 31, 1950.
The wettest calendar year on that record is 1950, with 50.40 in; the snowiest season is 1949–50, with 28.6 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00024234; records: ACIS (NOAA Regional Climate Centers), station USW00024234. Records use complete months only; a month missing more than three days is left out.
How humid and windy is it at Seattle Boeing Field, and how clear are the skies?
The summer (June-August) dew point averages 52°F. The muggiest month is July, with an average dew point of 54°F; the driest air comes in December (36°F). March is the windiest month (6.5 mph on average), and July has the most clear or nearly clear hours (62%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 37°F | 78% | 66% | 6.0 mph | – | – |
| February | 36°F | 73% | 58% | 6.0 mph | 37% | 39% |
| March | 39°F | 70% | 54% | 6.5 mph | 40% | 40% |
| April | 42°F | 65% | 49% | 6.3 mph | 37% | 32% |
| May | 48°F | 64% | 49% | 5.9 mph | 38% | 32% |
| June | 51°F | 61% | 45% | 5.5 mph | 50% | 22% |
| July | 54°F | 61% | 44% | 5.3 mph | 62% | 18% |
| August | 52°F | 64% | 45% | 5.1 mph | 60% | 15% |
| September | 49°F | 72% | 54% | 4.9 mph | 62% | 22% |
| October | 43°F | 78% | 64% | 5.4 mph | – | – |
| November | 37°F | 79% | 69% | 5.8 mph | – | – |
| December | 36°F | 80% | 71% | 5.6 mph | – | – |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024234. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is it at Seattle Boeing Field?
Over a year 67% of the sunlight that would reach the ground under clear skies gets through the clouds at Seattle Boeing Field, 3.4 kWh per square metre a day. August is the sunniest month (78%) and December the cloudiest (51%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 52% | 1.0 |
| February | 60% | 1.9 |
| March | 58% | 2.9 |
| April | 63% | 4.2 |
| May | 66% | 5.3 |
| June | 68% | 5.7 |
| July | 78% | 6.3 |
| August | 78% | 5.4 |
| September | 74% | 3.9 |
| October | 63% | 2.3 |
| November | 54% | 1.2 |
| December | 51% | 0.8 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How many heating and cooling degree days does Seattle Boeing Field record?
A normal year at Seattle Boeing Field brings 4,341 heating degree days, 19% fewer than the median U.S. place (5,373), and 282 cooling degree days, 69% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,392 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 691 | 0 |
| February | 595 | 0 |
| March | 555 | 0 |
| April | 400 | 1 |
| May | 230 | 10 |
| June | 107 | 35 |
| July | 26 | 101 |
| August | 19 | 104 |
| September | 98 | 32 |
| October | 351 | 1 |
| November | 557 | 0 |
| December | 713 | 0 |
| Year (annual) | 4,341 | 282 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024234. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Have recent years at Seattle Boeing Field been warmer than normal?
2024 averaged 54.7°F, 0.9°F above the 1991-2020 normal of 53.8°F. 1 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 53.5°F | −0.3°F | 23.97 |
| 2022 | 52.8°F | −1.0°F | 26.93 |
| 2023 | 53.5°F | −0.3°F | 19.44 |
| 2024 | 54.7°F | +0.9°F | 21.29 |
Over 47 complete years from 1948 to 2025, the station's annual mean temperature rose at a fitted 2.7°F per century (+0.15°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00024234; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Seattle Boeing Field's climate compare?
Seattle Boeing Field is warmer than 92 of the 96 places with their own NOAA record in Washington, and wetter than 56. Across the 7,247 U.S. stations with normals, its annual mean of 53.8°F is warmer than 56%.
In the Köppen classification computed from these normals, Seattle Boeing Field is Csb: temperate, dry-summer, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Seattle Boeing Field share this climate record?
4 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Mercer Island, WA25,302 people · 4 mi NE
- White Center, WA15,017 people · 3 mi SW
- Boulevard Park, WA4,334 people · 1 mi SW
- Beaux Arts Village, WA313 people · 6 mi NE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Seattle Boeing Field's climate
What is the coldest month at Seattle Boeing Field?
December, with a normal high of 48°F and a normal low of 36°F. The warmest is August (77°F by day, 58°F at night).
Does it snow at Seattle Boeing Field?
Yes. NOAA publishes no 1991-2020 snowfall normal for the station; the nearest record that keeps one, Seattle (6 miles away), records 6 inches of snow in a normal year.
What is the rainiest month at Seattle Boeing Field?
November, with 5.80 in of precipitation in a normal year; the driest is July with 0.56 in.
What plant hardiness zone is Seattle Boeing Field in?
The USDA's 2023 map puts Seattle Boeing Field in zone 9a in ZIP code 98108, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches 21°F (22 years, 1991-2020): zone 9a.
How late can frost come at Seattle Boeing Field?
In half of years the last 32°F night comes after March 13; in one year in ten it comes after April 1. Waiting until April 1 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Washington climateThe statewide normals and every place in the state
- Renton, WA5 miles from this station, 53.6°F a year
- Seattle, WA6 miles from this station, 53.7°F a year
- Kent, WA8 miles from this station, 53.8°F a year
- Seattle Sand Point Weather Office, WA11 miles from this station, 53.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made