Rosalia, Washington climate: Normal weather by month, frost dates and records
Rosalia's normal year runs from 24°F December nights to 86°F August afternoons, with 18.4 inches of precipitation and 26 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.9°C, December lows of −4°C, August highs of 30°C, 467 mm of precipitation a year.
- NOAA stationRosalia
- Station IDUSC00457180
- Location47.23°N 117.36°W
- Elevation2,420 ft (738 m)
- From the centerunder 1 mile
- Population578
On October 23, the normal high in Rosalia is 57°F and the normal low 33°F, and the chance of measurable rain or snow is 31%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Rosalia.
- Jan 37° 25°
- Feb 42° 26°
- Mar 50° 31°
- Apr 58° 35°
- May 67° 42°
- Jun 73° 47°
- Jul 85° 51°
- Aug 86° 51°
- Sep 76° 44°
- Oct 61° 35°
- Nov 45° 29°
- Dec 36° 24°
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 Rosalia each month?
August is the warmest month, with normal highs of 86°F; December the coldest, with normal lows of 24°F. The most precipitation falls in December (2.66 in), the least in August (0.42 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 37°F | 25°F | 30.6°F | 2.03 | 6.4 | 12 | <1 | 26 | 8 h 50 min |
| February | 42°F | 26°F | 33.9°F | 1.72 | 3.2 | 9 | <1 | 23 | 10 h 20 min |
| March | 50°F | 31°F | 40.1°F | 1.90 | 1.6 | 11 | <1 | 21 | 11 h 50 min |
| April | 58°F | 35°F | 46.4°F | 1.55 | 0.2 | 10 | <1 | 12 | 13 h 30 min |
| May | 67°F | 42°F | 54.6°F | 1.66 | 0.0 | 9 | <1 | 3 | 15 h |
| June | 73°F | 47°F | 60.2°F | 1.33 | 0.0 | 8 | 1 | <1 | 15 h 50 min |
| July | 85°F | 51°F | 68.2°F | 0.52 | 0.0 | 4 | 10 | <1 | 15 h 40 min |
| August | 86°F | 51°F | 68.3°F | 0.42 | 0.0 | 3 | 10 | <1 | 14 h 20 min |
| September | 76°F | 44°F | 59.8°F | 0.62 | 0.0 | 4 | 3 | 2 | 12 h 40 min |
| October | 61°F | 35°F | 47.9°F | 1.53 | 0.1 | 8 | <1 | 12 | 11 h |
| November | 45°F | 29°F | 37.2°F | 2.46 | 3.9 | 13 | <1 | 20 | 9 h 20 min |
| December | 36°F | 24°F | 30.3°F | 2.66 | 10.8 | 12 | <1 | 27 | 8 h 30 min |
| Year (annual) | 60°F | 37°F | 48.1°F | 18.40 | 26.2 | 104 | 25 | 146 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 3°C | −4°C | −0.8°C | 52 mm | 16 cm |
| February | 5°C | −3°C | 1.1°C | 44 mm | 8 cm |
| March | 10°C | −1°C | 4.5°C | 48 mm | 4 cm |
| April | 14°C | 2°C | 8.0°C | 39 mm | 1 cm |
| May | 20°C | 5°C | 12.6°C | 42 mm | 0 cm |
| June | 23°C | 8°C | 15.7°C | 34 mm | 0 cm |
| July | 29°C | 11°C | 20.1°C | 13 mm | 0 cm |
| August | 30°C | 11°C | 20.2°C | 11 mm | 0 cm |
| September | 24°C | 7°C | 15.4°C | 16 mm | 0 cm |
| October | 16°C | 2°C | 8.8°C | 39 mm | 0 cm |
| November | 7°C | −1°C | 2.9°C | 62 mm | 10 cm |
| December | 2°C | −4°C | −0.9°C | 68 mm | 27 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00457180; 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 Rosalia?
Normal highs sit between 65°F and 85°F in May, June, July and September. Of those, July has the fewest days with rain (4).
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 USC00457180.
When is the last frost in Rosalia?
In Rosalia, the last spring frost (32°F) comes after May 7 in half of years and after May 25 in one year in ten; the first autumn frost comes before September 28 in half of years and before September 11 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
- May 71 year in 10 after May 25; 9 in 10 after April 22
- First autumn frost, half of years before
- September 281 year in 10 before September 11; 9 in 10 before October 16
NOAA puts the median frost-free season at 144 days, and the season without a hard freeze (28°F) at 175 days.
A hard freeze (28°F) comes after April 20 in half of springs and before October 12 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Rosalia in zone 6b in ZIP code 99170, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Rosalia's NOAA station is in zone 6b: the coldest night of a typical year reaches −4°F (16 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 USC00457180; 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 Rosalia?
In a normal year in Rosalia, 25 days a year reach 90°F (2 of them 100°F or more), 146 nights fall to 32°F or colder and 104 days bring measurable precipitation.
- Days at 90°F or more
- 25a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 146a normal year
- Days that stay below freezing
- 24high of 32°F or less
- Days with 0.01 inch of precipitation
- 104a normal year
- Days with 1 inch of snow or more
- 13a normal year
The highest temperature in this station's record (since 1893) is 111°F, on July 1, 2021; the lowest is −29°F, on December 31, 1968.
The wettest calendar year on that record is 2012, with 28.35 in; the snowiest season is 1968–69, with 67.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00457180; records: ACIS (NOAA Regional Climate Centers), station USC00457180. Records use complete months only; a month missing more than three days is left out.
How sunny is Rosalia?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Rosalia, 3.8 kWh per square metre a day. July is the sunniest month (90%) and December the cloudiest (50%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 53% | 1.1 |
| February | 62% | 2.0 |
| March | 61% | 3.1 |
| April | 67% | 4.6 |
| May | 74% | 5.9 |
| June | 75% | 6.5 |
| July | 90% | 7.4 |
| August | 88% | 6.1 |
| September | 81% | 4.4 |
| October | 71% | 2.6 |
| November | 56% | 1.3 |
| December | 50% | 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 Rosalia need?
A normal year in Rosalia brings 6,509 heating degree days, 21% more than the median U.S. place (5,373), and 377 cooling degree days, 58% 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 2,044 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,066 | 0 |
| February | 871 | 0 |
| March | 772 | 0 |
| April | 558 | 0 |
| May | 334 | 10 |
| June | 179 | 33 |
| July | 49 | 148 |
| August | 45 | 147 |
| September | 193 | 37 |
| October | 531 | 1 |
| November | 834 | 0 |
| December | 1,077 | 0 |
| Year (annual) | 6,509 | 377 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00457180. 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 Rosalia been warmer than normal lately?
2025 averaged 50.3°F, 2.2°F above the 1991-2020 normal of 48.1°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 49.9°F | +1.8°F | 14.26 | – |
| 2022 | 47.7°F | −0.4°F | – | 43.5 |
| 2024 | 49.6°F | +1.5°F | 17.59 | 18.5 |
| 2025 | 50.3°F | +2.2°F | 15.28 | 21.4 |
Over 92 complete years from 1893 to 2025, the station's annual mean temperature rose at a fitted 1.6°F per century (+0.09°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00457180; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Rosalia's climate compare?
Rosalia is warmer than 16 of the other 95 places with their own NOAA record in Washington, and wetter than 37. Across the 7,247 U.S. stations with normals, its annual mean of 48.1°F is warmer than 32%.
In the Köppen classification computed from these normals, Rosalia is Dsb: continental, 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 Rosalia share this climate record?
2 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.
- Oakesdale, WA384 people · 9 mi SE
- Malden, WA252 people · 5 mi W
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 Rosalia's climate
What is the coldest month in Rosalia?
December, with a normal high of 36°F and a normal low of 24°F. The warmest is August (86°F by day, 51°F at night).
Does it snow in Rosalia?
Yes: 26 inches in a normal year, falling on 16 days with 0.1 inch or more, the most in December (10.8 inches).
What is the rainiest month in Rosalia?
December, with 2.66 in of precipitation in a normal year; the driest is August with 0.42 in.
What plant hardiness zone is Rosalia in?
The USDA's 2023 map puts Rosalia in zone 6b in ZIP code 99170, the nearest ZIP area. By the same method at Rosalia's NOAA station, the coldest night of a typical year reaches −4°F (16 years, 1991-2020): zone 6b.
How late can frost come in Rosalia?
In half of years the last 32°F night comes after May 7; in one year in ten it comes after May 25. Waiting until May 25 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Washington climateThe statewide normals and every place in the state
- St. John, WA14 miles from this station, 49.3°F a year
- Plummer, ID20 miles from this station, 46.5°F a year
- Spokane, WA28 miles from this station, 48.6°F a year
- Potlatch, ID30 miles from this station, 46.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made