Sedro-Woolley, Washington climate: Normal weather by month, frost dates and records
Sedro-Woolley's normal year runs from 34°F December nights to 75°F August afternoons, with 48.5 inches of precipitation and 6 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 10.7°C, December lows of 1°C, August highs of 24°C, 1,233 mm of precipitation a year.
- NOAA stationSedro-Woolley
- Station IDUSC00457507
- Location48.50°N 122.24°W
- Elevation60 ft (18 m)
- Population13,215
On October 23, the normal high in Sedro-Woolley is 57°F and the normal low 42°F, and the chance of measurable rain or snow is 62%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Sedro-Woolley.
- Jan 46° 35°
- Feb 49° 35°
- Mar 53° 38°
- Apr 58° 41°
- May 65° 47°
- Jun 69° 51°
- Jul 75° 53°
- Aug 75° 53°
- Sep 70° 49°
- Oct 60° 43°
- Nov 50° 39°
- Dec 45° 34°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Sedro-Woolley each month?
August is the warmest month, with normal highs of 75°F; December the coldest, with normal lows of 34°F. The most precipitation falls in November (7.02 in), the least in July (1.34 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 46°F | 35°F | 40.3°F | 6.18 | 0.6 | 20 | <1 | 12 | 8 h 40 min |
| February | 49°F | 35°F | 41.8°F | 4.11 | 0.2 | 17 | <1 | 10 | 10 h 10 min |
| March | 53°F | 38°F | 45.4°F | 4.76 | 0.4 | 20 | <1 | 5 | 11 h 50 min |
| April | 58°F | 41°F | 49.8°F | 4.17 | 0.0 | 17 | <1 | 1 | 13 h 40 min |
| May | 65°F | 47°F | 55.7°F | 3.46 | 0.0 | 14 | <1 | <1 | 15 h 10 min |
| June | 69°F | 51°F | 59.7°F | 2.60 | 0.0 | 13 | <1 | <1 | 16 h 10 min |
| July | 75°F | 53°F | 63.8°F | 1.34 | 0.0 | 7 | <1 | <1 | 15 h 50 min |
| August | 75°F | 53°F | 64.0°F | 1.60 | 0.0 | 7 | <1 | <1 | 14 h 20 min |
| September | 70°F | 49°F | 59.4°F | 2.86 | 0.0 | 12 | <1 | <1 | 12 h 40 min |
| October | 60°F | 43°F | 51.4°F | 4.98 | 0.1 | 18 | <1 | 1 | 11 h |
| November | 50°F | 39°F | 44.5°F | 7.02 | 0.7 | 21 | <1 | 6 | 9 h 20 min |
| December | 45°F | 34°F | 39.5°F | 5.45 | 3.7 | 21 | <1 | 11 | 8 h 20 min |
| Year (annual) | 60°F | 43°F | 51.3°F | 48.53 | 5.7 | 186 | 1 | 46 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 8°C | 2°C | 4.6°C | 157 mm | 2 cm |
| February | 9°C | 2°C | 5.4°C | 104 mm | 1 cm |
| March | 12°C | 3°C | 7.4°C | 121 mm | 1 cm |
| April | 15°C | 5°C | 9.9°C | 106 mm | 0 cm |
| May | 18°C | 8°C | 13.2°C | 88 mm | 0 cm |
| June | 20°C | 10°C | 15.4°C | 66 mm | 0 cm |
| July | 24°C | 12°C | 17.7°C | 34 mm | 0 cm |
| August | 24°C | 12°C | 17.8°C | 41 mm | 0 cm |
| September | 21°C | 10°C | 15.2°C | 73 mm | 0 cm |
| October | 15°C | 6°C | 10.8°C | 126 mm | 0 cm |
| November | 10°C | 4°C | 6.9°C | 178 mm | 2 cm |
| December | 7°C | 1°C | 4.2°C | 138 mm | 9 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00457507; 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.
When is the best weather to visit Sedro-Woolley?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, July has the fewest days with rain (7).
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 USC00457507.
When is the last frost in Sedro-Woolley?
In Sedro-Woolley, the last spring frost (32°F) comes after March 27 in half of years and after April 17 in one year in ten; the first autumn frost comes before November 6 in half of years and before October 15 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 271 year in 10 after April 17; 9 in 10 after March 8
- First autumn frost, half of years before
- November 61 year in 10 before October 15; 9 in 10 before November 28
NOAA puts the median frost-free season at 224 days, and the season without a hard freeze (28°F) at 268 days.
A hard freeze (28°F) comes after March 1 in half of springs and before November 24 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Sedro-Woolley in zone 8b in ZIP code 98235, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Sedro-Woolley's NOAA station is in zone 8b: the coldest night of a typical year reaches 18°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 USC00457507; 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 in Sedro-Woolley?
In a normal year in Sedro-Woolley, 1 day a year reaches 90°F, 46 nights fall to 32°F or colder and 186 days bring measurable precipitation.
- Days at 90°F or more
- 1a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 46a normal year
- Days that stay below freezing
- 2high of 32°F or less
- Days with 0.01 inch of precipitation
- 186a normal year
- Days with 1 inch of snow or more
- 2a normal year
The highest temperature in this station's record (since 1896) is 99°F, on June 30, 1915; the lowest is −2°F, on January 26, 1957.
The wettest calendar year on that record is 1990, with 69.20 in; the snowiest season is 1949–50, with 41.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00457507; records: ACIS (NOAA Regional Climate Centers), station USC00457507. Records use complete months only; a month missing more than three days is left out.
How sunny is Sedro-Woolley?
Over a year 70% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Sedro-Woolley, 3.5 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (51%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 52% | 1.0 |
| February | 61% | 1.9 |
| March | 61% | 2.9 |
| April | 67% | 4.3 |
| May | 71% | 5.5 |
| June | 72% | 6.0 |
| July | 82% | 6.5 |
| August | 81% | 5.5 |
| September | 76% | 3.9 |
| October | 64% | 2.2 |
| November | 55% | 1.1 |
| 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 much heating and cooling does Sedro-Woolley need?
A normal year in Sedro-Woolley brings 5,070 heating degree days, 6% fewer than the median U.S. place (5,373), and 86 cooling degree days, 90% 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 1,803 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 764 | 0 |
| February | 648 | 0 |
| March | 608 | 0 |
| April | 456 | 0 |
| May | 289 | 3 |
| June | 168 | 9 |
| July | 71 | 34 |
| August | 63 | 34 |
| September | 175 | 7 |
| October | 422 | 0 |
| November | 615 | 0 |
| December | 790 | 0 |
| Year (annual) | 5,070 | 86 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00457507. 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.
Has Sedro-Woolley been warmer than normal lately?
2025 averaged 51.7°F, 0.4°F above the 1991-2020 normal of 51.3°F. 2 of the 3 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2022 | 51.2°F | −0.1°F | 45.55 | – |
| 2024 | 51.5°F | +0.2°F | 56.17 | 2.1 |
| 2025 | 51.7°F | +0.4°F | 44.33 | 0.0 |
Over 84 complete years from 1897 to 2025, the station's annual mean temperature rose at a fitted 2.0°F per century (+0.11°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00457507; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Sedro-Woolley's climate compare?
Sedro-Woolley is warmer than 66 of the other 95 places with their own NOAA record in Washington, and wetter than 66. Across the 7,247 U.S. stations with normals, its annual mean of 51.3°F is warmer than 46%.
In the Köppen classification computed from these normals, Sedro-Woolley 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 Sedro-Woolley share this climate record?
6 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.
- Big Lake, WA2,648 people · 7 mi S
- Clear Lake, WA1,176 people · 3 mi S
- Alger, WA655 people · 9 mi NW
- Lyman, WA422 people · 8 mi E
- Hamilton, WA295 people · 11 mi E
- Acme, WA284 people · 15 mi N
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 Sedro-Woolley's climate
What is the coldest month in Sedro-Woolley?
December, with a normal high of 45°F and a normal low of 34°F. The warmest is August (75°F by day, 53°F at night).
Does it snow in Sedro-Woolley?
Yes: 6 inches in a normal year, falling on 3 days with 0.1 inch or more, the most in December (3.7 inches).
What is the rainiest month in Sedro-Woolley?
November, with 7.02 in of precipitation in a normal year; the driest is July with 1.34 in.
What plant hardiness zone is Sedro-Woolley in?
The USDA's 2023 map puts Sedro-Woolley in zone 8b in ZIP code 98235, the nearest ZIP area. By the same method at Sedro-Woolley's NOAA station, the coldest night of a typical year reaches 18°F (22 years, 1991-2020): zone 8b.
How late can frost come in Sedro-Woolley?
In half of years the last 32°F night comes after March 27; in one year in ten it comes after April 17. Waiting until April 17 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Washington climateThe statewide normals and every place in the state
- Mount Vernon, WA8 miles from this station, 51.5°F a year
- Anacortes, WA17 miles from this station, 52.8°F a year
- Arlington, WA21 miles from this station, 49.1°F a year
- Whidbey Island Naval Air Station, WA22 miles from this station, 52.1°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made