Seattle, WA climate: monthly averages and frost dates
Seattle, WA has cool winters and mild summers by this site's scale, with moderate annual precipitation. The figures are the 1991–2020 climate normals for NOAA station USW00024233 (SEATTLE TACOMA INTL AP), 12 mi (20 km) in a straight line from the city's center point (US Census).
- Warmest month high
- 77.6°F
- August
- Coldest month mean
- 42.0°F
- December
- Precipitation
- 39.3 in
- per year
- Snowfall
- 6.3 in
- per year
- Median last frost
- March 2
- 32°F, spring
- Median first frost
- November 23
- 32°F, autumn
Monthly averages in Seattle
| Month | High °F | Low °F | Mean °F | Precip. in | Snow in | Days ≥0.01 in | Days ≥90°F | Nights ≤32°F |
|---|---|---|---|---|---|---|---|---|
| January | 48.0 | 37.7 | 42.8 | 5.78 | 1.8 | 18.7 | 0.0 | 7.0 |
| February | 50.3 | 37.7 | 44.0 | 3.76 | 2.2 | 15.9 | 0.0 | 5.8 |
| March | 54.2 | 39.9 | 47.1 | 4.17 | 0.4 | 17.1 | 0.0 | 1.9 |
| April | 59.3 | 43.3 | 51.3 | 3.18 | 0.0 | 15.0 | 0.0 | 0.1 |
| May | 66.3 | 48.7 | 57.5 | 1.88 | 0.0 | 11.3 | 0.0 | 0.0 |
| June | 71.1 | 53.0 | 62.0 | 1.45 | 0.0 | 9.2 | 0.6 | 0.0 |
| July | 77.4 | 56.8 | 67.1 | 0.60 | 0.0 | 4.7 | 1.8 | 0.0 |
| August | 77.6 | 57.2 | 67.4 | 0.97 | 0.0 | 4.9 | 1.2 | 0.0 |
| September | 71.6 | 53.6 | 62.6 | 1.61 | 0.0 | 8.3 | 0.2 | 0.0 |
| October | 60.5 | 47.0 | 53.8 | 3.91 | 0.0 | 14.3 | 0.0 | 0.2 |
| November | 52.1 | 40.9 | 46.5 | 6.31 | 0.2 | 18.4 | 0.0 | 3.0 |
| December | 47.0 | 37.1 | 42.0 | 5.72 | 1.7 | 18.4 | 0.0 | 7.2 |
| Year | 61.3 | 46.1 | 53.7 | 39.34 | 6.3 | 156.2 | 3.8 | 25.2 |
How cold is winter in Seattle?
Winters in Seattle are cool by this site's scale (coldest-month mean 32 to under 45°F). The coldest month is December, with a mean temperature of 42.0°F (5.6°C), a normal daily high of 47.0°F (8.3°C) and a normal daily low of 37.1°F (2.8°C).
The station averages 25.2 nights a year at or below 32°F and 1.2 days when the high stays at or below 32°F.
How hot is summer in Seattle?
Summers in Seattle are mild by this site's scale (hottest-month high 70 to under 80°F). August has the highest normal daily high, 77.6°F (25.3°C), with nights averaging 57.2°F (14.0°C).
The high reaches 90°F or more on 3.8 days in a normal year.
What is the wettest month in Seattle?
Seattle gets 39.34 in (999 mm) of precipitation in a normal year, which this site classes as moderate (20 to under 40 in a year). The wettest month is November with 6.31 in (160 mm); the driest is July with 0.60 in (15 mm).
Measurable precipitation (0.01 in or more) falls on 156.2 days a year.
Does it snow in Seattle?
Normal annual snowfall in Seattle is 6.3 in (16 cm), which this site classes as light (1 to under 12 in a year).
February is the snowiest month, with 2.2 in (6 cm).
A day with 1.0 in or more of snowfall comes 1.9 times a year on average.
Which months are mild in Seattle?
5 months in Seattle meet this site's comfort thresholds (normal high 65–85°F, low 45°F or higher, fewer than 10 days with 0.10 in or more of precipitation): May to September.
Thresholds and their limits: methodology.
Frost dates and growing season in Seattle
In Seattle the median last spring night at or below 32°F is March 2, and the median first autumn one is November 23 (NOAA P50 dates). NOAA's median length of the freeze-free season is 266 days.
There is still a 10% chance of a 32°F night on or after March 23, and a 10% chance that the first one has come by November 6.
The chance that the last spring 32°F night comes on or after February 5 is 90%.
For a hard freeze (28°F or lower) the median dates are February 4 in spring and December 10 in autumn.
| Chance | Last spring 32°F night on or after | First autumn 32°F night by | Freeze-free season, days |
|---|---|---|---|
| 10% | March 23 | November 6 | 298 |
| 20% | March 16 | November 11 | 286 |
| 30% | March 12 | November 14 | 279 |
| 40% | March 7 | November 18 | 272 |
| 50% | March 2 | November 23 | 266 |
| 60% | February 27 | November 28 | 260 |
| 70% | February 22 | December 2 | 254 |
| 80% | February 16 | December 7 | 246 |
| 90% | February 5 | December 15 | 239 |
| Threshold | Median last date (spring) | Median first date (autumn or winter) | Median season, days |
|---|---|---|---|
| 36°F | March 31 | November 7 | 219 |
| 32°F | March 2 | November 23 | 266 |
| 28°F | February 4 | December 10 | 315 |
| 24°F | January 4 | December 17 | 355 |
| 20°F | No such night in most years, though a few years have one; no typical season to show | ||
| 16°F | No such night in a typical year (NOAA publishes no dates) | ||
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 90% | 85% | 53% | 2% | 0% | 0% | 0% | 0% | 0% | 4% | 64% | 94% |
Nearby and similar places
Of the places on this site, the closest to Seattle by station distance are Portland, OR at 129 mi (207 km), Spokane, WA at 224 mi (360 km) and Boise, ID at 398 mi (640 km).
Among places whose winter, summer and precipitation words are each within one band of Seattle's (winter: cool, summer: mild, precipitation: moderate), the closest monthly temperature and precipitation patterns are Portland, OR, Boston, MA and San Francisco, CA.
Compared with Portland, OR, Seattle's peak-month normal high is 4.7°F (2.6°C) lower, its coldest-month mean is 0.4°F (0.2°C) higher, and its annual precipitation is 2.42 in more.
| Place | Listed as | Station distance | Coldest mean °F | Warmest high °F | Precip. in/yr | Snow in/yr | Last frost |
|---|---|---|---|---|---|---|---|
| Seattle, WA | this page | – | 42.0 | 77.6 | 39.3 | 6.3 | March 2 |
| Portland, OR | nearby, similar | 129 mi (207 km) | 41.6 | 82.3 | 36.9 | 4.2 | March 13 |
| Spokane, WA | nearby | 224 mi (360 km) | 29.1 | 84.4 | 16.4 | 45.4 | April 26 |
| Boise, ID | nearby | 398 mi (640 km) | 32.1 | 92.7 | 11.5 | 17.6 | April 24 |
| Boston, MA | similar | 2,489 mi (4,006 km) | 29.9 | 82.1 | 43.6 | 49.2 | April 4 |
| San Francisco, CA | similar | 679 mi (1,092 km) | 51.3 | 74.8 | 19.6 | – | rare freeze |
How nearby and similar places are chosen: methodology.
Source and station
The data for Seattle come from NOAA station SEATTLE TACOMA INTL AP, WA US (USW00024233) at 47.4444, -122.3139, elevation 370 ft (113 m). It lies 12 mi (20 km) in a straight line from the center point of Seattle city, the “internal point” in the US Census 2024 Gazetteer.
Each monthly normal used here rests on at least 17 years of data from 1991–2020 (NOAA's per-field year counts).
NOAA completeness flags on the monthly fields used here:
- P: Provisional: meets WMO standards for data availability for 10 or more years (missing months cannot be filled).
- S: Standard: meets WMO standards for data availability for 24 or more years.
Cite the data as:
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). Station USW00024233 (SEATTLE TACOMA INTL AP, WA US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/wck8-er13. Accessed 2026-10-09.
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020). Station USW00024233 (SEATTLE TACOMA INTL AP, WA US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/4ek7-fk11. Accessed 2026-10-09.
Files used: monthly normals CSV, annual/seasonal normals CSV (retrieved 2026-10-09). The values on this page as JSON: /us/wa/seattle/data.json.