St. John, Washington climate: Normal weather by month, frost dates and records
St. John's normal year runs from 28°F December nights to 84°F July afternoons, with 17.1 inches of precipitation and 27 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.6°C, December lows of −2°C, July highs of 29°C, 433 mm of precipitation a year.
- NOAA stationSt John
- Station IDUSC00457267
- Location47.09°N 117.59°W
- Elevation1,952 ft (595 m)
- Population590
On October 23, the normal high in St. John is 55°F and the normal low 37°F, and the chance of measurable rain or snow is 33%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for St. John.
- Jan 37° 29°
- Feb 41° 30°
- Mar 49° 34°
- Apr 57° 38°
- May 66° 45°
- Jun 73° 50°
- Jul 84° 54°
- Aug 84° 53°
- Sep 74° 47°
- Oct 59° 39°
- Nov 44° 33°
- Dec 35° 28°
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 St. John each month?
July is the warmest month, with normal highs of 84°F; December the coldest, with normal lows of 28°F. The most precipitation falls in December (2.38 in), the least in August (0.34 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 37°F | 29°F | 32.6°F | 2.05 | 8.8 | 14 | <1 | 22 | 8 h 50 min |
| February | 41°F | 30°F | 35.7°F | 1.52 | 2.7 | 11 | <1 | 20 | 10 h 20 min |
| March | 49°F | 34°F | 41.8°F | 1.90 | 1.4 | 12 | <1 | 16 | 11 h 50 min |
| April | 57°F | 38°F | 47.7°F | 1.54 | 0.4 | 10 | <1 | 9 | 13 h 30 min |
| May | 66°F | 45°F | 55.6°F | 1.56 | 0.0 | 9 | <1 | 2 | 15 h |
| June | 73°F | 50°F | 61.4°F | 1.12 | 0.0 | 8 | 2 | <1 | 15 h 50 min |
| July | 84°F | 54°F | 69.0°F | 0.43 | 0.0 | 3 | 12 | <1 | 15 h 30 min |
| August | 84°F | 53°F | 68.4°F | 0.34 | 0.0 | 3 | 11 | <1 | 14 h 20 min |
| September | 74°F | 47°F | 60.3°F | 0.56 | 0.0 | 4 | 3 | 1 | 12 h 40 min |
| October | 59°F | 39°F | 48.8°F | 1.50 | 0.1 | 9 | <1 | 10 | 11 h |
| November | 44°F | 33°F | 38.5°F | 2.15 | 2.5 | 13 | <1 | 16 | 9 h 20 min |
| December | 35°F | 28°F | 31.5°F | 2.38 | 10.7 | 14 | <1 | 25 | 8 h 30 min |
| Year (annual) | 59°F | 40°F | 49.3°F | 17.05 | 26.6 | 110 | 28 | 123 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 3°C | −2°C | 0.3°C | 52 mm | 22 cm |
| February | 5°C | −1°C | 2.1°C | 39 mm | 7 cm |
| March | 10°C | 1°C | 5.4°C | 48 mm | 4 cm |
| April | 14°C | 3°C | 8.7°C | 39 mm | 1 cm |
| May | 19°C | 7°C | 13.1°C | 40 mm | 0 cm |
| June | 23°C | 10°C | 16.3°C | 28 mm | 0 cm |
| July | 29°C | 12°C | 20.6°C | 11 mm | 0 cm |
| August | 29°C | 12°C | 20.2°C | 9 mm | 0 cm |
| September | 23°C | 8°C | 15.7°C | 14 mm | 0 cm |
| October | 15°C | 4°C | 9.3°C | 38 mm | 0 cm |
| November | 7°C | 1°C | 3.6°C | 55 mm | 6 cm |
| December | 2°C | −2°C | −0.3°C | 60 mm | 27 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00457267; 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 St. John?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, August 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 USC00457267.
When is the last frost in St. John?
In St. John, the last spring frost (32°F) comes after April 29 in half of years and after May 15 in one year in ten; the first autumn frost comes before October 4 in half of years and before September 19 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 291 year in 10 after May 15; 9 in 10 after April 9
- First autumn frost, half of years before
- October 41 year in 10 before September 19; 9 in 10 before October 23
NOAA puts the median frost-free season at 161 days, and the season without a hard freeze (28°F) at 198 days.
A hard freeze (28°F) comes after April 5 in half of springs and before October 20 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts St. John in zone 6b in ZIP code 99171, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, St. John's NOAA station is in zone 6b: the coldest night of a typical year reaches 0°F (26 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 USC00457267; 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 St. John?
In a normal year in St. John, 28 days a year reach 90°F (2 of them 100°F or more), 123 nights fall to 32°F or colder and 110 days bring measurable precipitation.
- Days at 90°F or more
- 28a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 123a normal year
- Days that stay below freezing
- 19high of 32°F or less
- Days with 0.01 inch of precipitation
- 110a normal year
- Days with 1 inch of snow or more
- 9a normal year
The highest temperature in this station's record (since 1963) is 108°F, on August 9, 2018; the lowest is −28°F, on January 6, 1982.
The wettest calendar year on that record is 2012, with 24.97 in; the snowiest season is 2008–09, with 86.3 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00457267; records: ACIS (NOAA Regional Climate Centers), station USC00457267. Records use complete months only; a month missing more than three days is left out.
How sunny is St. John?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around St. John, 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 St. John need?
A normal year in St. John brings 6,085 heating degree days, 13% more than the median U.S. place (5,373), and 375 cooling degree days, 59% 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 2,154 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,003 | 0 |
| February | 820 | 0 |
| March | 721 | 0 |
| April | 519 | 0 |
| May | 300 | 8 |
| June | 143 | 35 |
| July | 31 | 155 |
| August | 36 | 142 |
| September | 175 | 34 |
| October | 503 | 1 |
| November | 795 | 0 |
| December | 1,038 | 0 |
| Year (annual) | 6,085 | 375 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00457267. 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.
How does St. John's climate compare?
St. John is warmer than 29 of the other 95 places with their own NOAA record in Washington, and wetter than 33. Across the 7,247 U.S. stations with normals, its annual mean of 49.3°F is warmer than 37%.
In the Köppen classification computed from these normals, St. John 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 St. John 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.
- Steptoe, WA152 people · 13 mi SE
- Lamont, WA78 people · 17 mi NW
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 St. John's climate
What is the coldest month in St. John?
December, with a normal high of 35°F and a normal low of 28°F. The warmest is July (84°F by day, 54°F at night).
Does it snow in St. John?
Yes: 27 inches in a normal year, falling on 19 days with 0.1 inch or more, the most in December (10.7 inches).
What is the rainiest month in St. John?
December, with 2.38 in of precipitation in a normal year; the driest is August with 0.34 in.
What plant hardiness zone is St. John in?
The USDA's 2023 map puts St. John in zone 6b in ZIP code 99171, the nearest ZIP area. By the same method at St. John's NOAA station, the coldest night of a typical year reaches 0°F (26 years, 1991-2020): zone 6b.
How late can frost come in St. John?
In half of years the last 32°F night comes after April 29; in one year in ten it comes after May 15. Waiting until May 15 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Washington climateThe statewide normals and every place in the state
- Rosalia, WA14 miles from this station, 48.1°F a year
- LaCrosse, WA24 miles from this station, 50.1°F a year
- Pullman, WA33 miles from this station, 48.6°F a year
- Plummer, ID34 miles from this station, 46.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made