Monroe, Washington climate: Normal weather by month, frost dates and records
Monroe's normal year runs from 32°F December nights to 75°F August afternoons, with 50.8 inches of precipitation and 3 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.7°C, December lows of 0°C, August highs of 24°C, 1,290 mm of precipitation a year.
- NOAA stationMonroe
- Station IDUSC00455525
- Location47.85°N 121.99°W
- Elevation120 ft (37 m)
- Population19,927
On October 23, the normal high in Monroe is 55°F and the normal low 40°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 Monroe.
- Jan 44° 32°
- Feb 48° 32°
- Mar 52° 35°
- Apr 57° 39°
- May 64° 44°
- Jun 68° 49°
- Jul 74° 52°
- Aug 75° 52°
- Sep 69° 48°
- Oct 58° 41°
- Nov 49° 35°
- Dec 43° 32°
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 Monroe each month?
August is the warmest month, with normal highs of 75°F; December the coldest, with normal lows of 32°F. The most precipitation falls in November (7.16 in), the least in July (1.15 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 44°F | 32°F | 38.0°F | 6.54 | 0.1 | 20 | <1 | 13 | 8 h 50 min |
| February | 48°F | 32°F | 39.8°F | 4.47 | 2.2 | 17 | <1 | 12 | 10 h 10 min |
| March | 52°F | 35°F | 43.4°F | 5.22 | 0.2 | 20 | <1 | 8 | 11 h 50 min |
| April | 57°F | 39°F | 48.0°F | 4.30 | 0.0 | 17 | <1 | 3 | 13 h 40 min |
| May | 64°F | 44°F | 53.9°F | 3.42 | 0.0 | 14 | <1 | <1 | 15 h 10 min |
| June | 68°F | 49°F | 58.3°F | 2.69 | 0.0 | 12 | <1 | <1 | 16 h |
| July | 74°F | 52°F | 63.0°F | 1.15 | 0.0 | 6 | 1 | <1 | 15 h 40 min |
| August | 75°F | 52°F | 63.1°F | 1.30 | 0.0 | 6 | <1 | <1 | 14 h 20 min |
| September | 69°F | 48°F | 58.1°F | 2.73 | 0.0 | 11 | <1 | <1 | 12 h 40 min |
| October | 58°F | 41°F | 49.5°F | 5.03 | 0.0 | 18 | <1 | 2 | 11 h |
| November | 49°F | 35°F | 41.9°F | 7.16 | 0.3 | 22 | <1 | 9 | 9 h 20 min |
| December | 43°F | 32°F | 37.1°F | 6.76 | 0.2 | 22 | <1 | 14 | 8 h 30 min |
| Year (annual) | 58°F | 41°F | 49.5°F | 50.77 | 3.0 | 187 | 2 | 60 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 7°C | 0°C | 3.3°C | 166 mm | 0 cm |
| February | 9°C | 0°C | 4.3°C | 114 mm | 6 cm |
| March | 11°C | 2°C | 6.3°C | 133 mm | 1 cm |
| April | 14°C | 4°C | 8.9°C | 109 mm | 0 cm |
| May | 18°C | 7°C | 12.2°C | 87 mm | 0 cm |
| June | 20°C | 9°C | 14.6°C | 68 mm | 0 cm |
| July | 23°C | 11°C | 17.2°C | 29 mm | 0 cm |
| August | 24°C | 11°C | 17.3°C | 33 mm | 0 cm |
| September | 20°C | 9°C | 14.5°C | 69 mm | 0 cm |
| October | 14°C | 5°C | 9.7°C | 128 mm | 0 cm |
| November | 9°C | 2°C | 5.5°C | 182 mm | 1 cm |
| December | 6°C | 0°C | 2.8°C | 172 mm | 1 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00455525; 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 Monroe?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, August has the fewest days with rain (6).
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 USC00455525.
When is the last frost in Monroe?
In Monroe, the last spring frost (32°F) comes after April 17 in half of years and after May 7 in one year in ten; the first autumn frost comes before October 23 in half of years and before October 7 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
- April 171 year in 10 after May 7; 9 in 10 after March 29
- First autumn frost, half of years before
- October 231 year in 10 before October 7; 9 in 10 before November 9
NOAA puts the median frost-free season at 188 days, and the season without a hard freeze (28°F) at 225 days.
A hard freeze (28°F) comes after March 26 in half of springs and before November 8 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Monroe in zone 8b in ZIP code 98272, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Monroe's NOAA station is in zone 8b: the coldest night of a typical year reaches 17°F (23 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 USC00455525; 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 Monroe?
In a normal year in Monroe, 2 days a year reach 90°F, 60 nights fall to 32°F or colder and 187 days bring measurable precipitation.
- Days at 90°F or more
- 2a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 60a normal year
- Days that stay below freezing
- 3high of 32°F or less
- Days with 0.01 inch of precipitation
- 187a normal year
- Days with 1 inch of snow or more
- 1a normal year
The highest temperature in this station's record (since 1929) is 102°F, on July 29, 2009; the lowest is −3°F, on January 18, 1950.
The wettest calendar year on that record is 1996, with 65.45 in; the snowiest season is 1949–50, with 70.1 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00455525; records: ACIS (NOAA Regional Climate Centers), station USC00455525. Records use complete months only; a month missing more than three days is left out.
How sunny is Monroe?
Over a year 73% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Monroe, 3.8 kWh per square metre a day. July is the sunniest month (86%) and December the cloudiest (54%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 56% | 1.2 |
| February | 64% | 2.1 |
| March | 63% | 3.1 |
| April | 67% | 4.6 |
| May | 70% | 5.7 |
| June | 74% | 6.3 |
| July | 86% | 7.0 |
| August | 85% | 5.9 |
| September | 79% | 4.3 |
| October | 69% | 2.5 |
| November | 58% | 1.3 |
| December | 54% | 0.9 |
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 Monroe need?
A normal year in Monroe brings 5,696 heating degree days, 6% more than the median U.S. place (5,373), and 67 cooling degree days, 93% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,550 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 836 | 0 |
| February | 704 | 0 |
| March | 670 | 0 |
| April | 510 | 0 |
| May | 343 | 1 |
| June | 207 | 6 |
| July | 91 | 29 |
| August | 85 | 26 |
| September | 210 | 4 |
| October | 482 | 0 |
| November | 693 | 0 |
| December | 865 | 0 |
| Year (annual) | 5,696 | 67 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00455525. 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 Monroe been warmer than normal lately?
2025 averaged 53.0°F, 3.5°F above the 1991-2020 normal of 49.5°F. 4 of the 4 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2022 | 49.9°F | +0.4°F | 55.55 | – |
| 2023 | 52.6°F | +3.1°F | 47.66 | 0.0 |
| 2024 | 52.8°F | +3.3°F | 53.38 | – |
| 2025 | 53.0°F | +3.5°F | 45.53 | – |
Over 60 complete years from 1930 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 USC00455525; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Monroe's climate compare?
Monroe is warmer than 30 of the other 95 places with their own NOAA record in Washington, and wetter than 70. Across the 7,247 U.S. stations with normals, its annual mean of 49.5°F is warmer than 38%.
In the Köppen classification computed from these normals, Monroe 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 Monroe share this climate record?
15 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.
- Cottage Lake, WA23,170 people · 8 mi SW
- Maltby, WA10,859 people · 6 mi SW
- Snohomish, WA10,534 people · 7 mi NW
- Duvall, WA9,176 people · 8 mi S
- Woods Creek, WA7,027 people · 5 mi NE
- Chain Lake, WA4,989 people · 4 mi N
- Bunk Foss, WA3,718 people · 9 mi NW
- Clearview, WA3,508 people · 7 mi W
- Three Lakes, WA3,466 people · 8 mi N
- High Bridge, WA3,147 people · 3 mi SW
- Monroe North, WA2,069 people · 3 mi N
- Cathcart, WA1,878 people · 5 mi W
- Cavalero, WA1,850 people · 10 mi NW
- Machias, WA1,112 people · 10 mi N
- Lake Roesiger, WA981 people · 10 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 Monroe's climate
What is the coldest month in Monroe?
December, with a normal high of 43°F and a normal low of 32°F. The warmest is August (75°F by day, 52°F at night).
Does it snow in Monroe?
Yes: 3 inches in a normal year, falling on 2 days with 0.1 inch or more, the most in February (2.2 inches).
What is the rainiest month in Monroe?
November, with 7.16 in of precipitation in a normal year; the driest is July with 1.15 in.
What plant hardiness zone is Monroe in?
The USDA's 2023 map puts Monroe in zone 8b in ZIP code 98272, the nearest ZIP area. By the same method at Monroe's NOAA station, the coldest night of a typical year reaches 17°F (23 years, 1991-2020): zone 8b.
How late can frost come in Monroe?
In half of years the last 32°F night comes after April 17; in one year in ten it comes after May 7. Waiting until May 7 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Washington climateThe statewide normals and every place in the state
- Startup, WA13 miles from this station, 51.6°F a year
- Everett, WA14 miles from this station, 51.4°F a year
- Seattle Sand Point Weather Office, WA16 miles from this station, 53.2°F a year
- Tolt S Fork Reservoir, WA17 miles from this station, 48.1°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made