Prosser, WA Climate: Temperature & Rain by Month
Annual temperature and rainfall from NOAA NCEI's 1991–2020 normals →; comfort score computed by PlainClimate
30-year climate normals (1991-2020) from Prosser's primary NOAA station, PROSSER.
The climate verdict for Prosser
Dryness leads the climate profile for Prosser, Washington, with 8.7 inches of precipitation a year. NOAA records an annual average of 53°F. At 45/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 16% of scores.
- 53°F
- average temperature, NOAA 1991-2020 normal
- 45/100
- comfort score, above 16% of station-mapped location scores
- 8.7"
- annual precipitation
- 191 days
- frost-free growing season
Prosser: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00456768 · Prosser, WA 53°F mean · 8.7" precip
TEMP-COOL · RANK-MID · PHOTO-FINISH · PRCP-ARID · SWING-MID · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 53°F
- RANK-MID #3,636
- PHOTO-FINISH ≈ Molloy Cercom
- PRCP-ARID 8.7"
- SWING-MID 42°F
- COMF-LOW 45/100
- LOAD-HEAT 5,172 HDD
- STN-1 USC00456768
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Molloy Cercom, NY (+ 0.1 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every WA station list.
- Prosser (this station) 53°F
- Hot Woodstock, VA 53°F
- Near Molloy Cercom, NY 53°F
- Near Stonewall Jacks…, WV 53°F
- Near Islip LI Macart…, NY 53°F
Climate Living Index · Prosser
Prosser: 44/100 · grade D
Prosser publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Prosser, not an official NOAA rating. Rankings still use Comfort Score 45/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Frost-free season | 191 days/year | 58/100 · C |
| Annual temperature balance | 53.0°F · 14.5° from 67.5°F | 53/100 · D |
| Normal heat + freeze calendar | 144 calendar days | 51/100 · D |
| Precipitation balance | 8.7 in · 26.3 from 35 in | 9/100 · F |
Prosser · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Prosser's normals sit in a dry climate class: BSk
Precipitation is low relative to temperature but above true desert thresholds: cold semi-arid steppe (BSk). Class BSk is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: dry (arid or semi-arid), specifically cold semi-arid steppe.
- Köppen code
- BSk
- Group
- Dry (arid or semi-arid)
- Warmest month
- 75.0°F
- Coldest month
- 32.9°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Prosser sits across the climate record
Three NOAA fields for Prosser's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 53rd percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- Drier than 96%
- Prosser's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 45th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Prosser compares across U.S. station-mapped locations
Prosser's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
45 16th percentile score exceeds 16% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). This entry sits in this band.
- 50–60: 1,329 station-mapped locations (21%). Above this entry.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Prosser's measured station temperature trend
MethodologyAcross 56 complete annual observations from 1931 to 2020, PROSSER warmed at a fitted rate of 0.20°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Prosser primary station fitted change +0.20 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 40°F (5°C) | 27°F (-3°C) | 34°F (1°C) | 1.2" | 24.5 | 0.0 |
| February | 47°F (8°C) | 29°F (-2°C) | 38°F (3°C) | 0.9" | 20.7 | 0.0 |
| March | 56°F (13°C) | 35°F (2°C) | 45°F (7°C) | 0.7" | 11.8 | 0.0 |
| April | 65°F (18°C) | 40°F (4°C) | 52°F (11°C) | 0.7" | 4.2 | 0.0 |
| May | 74°F (23°C) | 48°F (9°C) | 61°F (16°C) | 0.9" | 0.3 | 2.0 |
| June | 81°F (27°C) | 54°F (12°C) | 67°F (20°C) | 0.7" | 0.0 | 5.6 |
| July | 90°F (32°C) | 60°F (15°C) | 75°F (24°C) | 0.2" | 0.0 | 17.9 |
| August | 89°F (32°C) | 58°F (14°C) | 73°F (23°C) | 0.2" | 0.0 | 17.3 |
| September | 80°F (27°C) | 50°F (10°C) | 65°F (18°C) | 0.3" | 0.4 | 3.8 |
| October | 65°F (18°C) | 41°F (5°C) | 53°F (12°C) | 0.8" | 4.2 | 0.0 |
| November | 49°F (10°C) | 32°F (0°C) | 41°F (5°C) | 0.9" | 17.5 | 0.0 |
| December | 40°F (4°C) | 26°F (-3°C) | 33°F (0°C) | 1.3" | 25.0 | 0.0 |
The year, day by day
Prosser works both ends of the calendar. Normal highs climb to 93°F by July 26 and hold at or above 90°F on 33 dates, then normal lows drop to freezing or below on 111 dates, bottoming at 26°F around December 21.
When the heat sits
Normal highs reach 90°F from July 12 through August 13, covering 33 dates. The broader mild season, normal highs of 70°F or more, runs May 2 to October 6.
This counts calendar dates whose 1991–2020 normal high reaches 90°F. It is a smaller number than the 90°F+ day counts in the monthly table above, which measure how often the threshold was actually crossed in a typical year. A date can average 88°F and still exceed 90°F in half of all years.
The freezing stretch
The normal low stays at or below 32°F into March 3, then returns to freezing around November 14, covering 111 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is January 4, when 27% of years recorded at least a hundredth of an inch. The driest is August 1 at 5%. Summed across the calendar, that is about 62 wet dates a year.
The widest day
July 31 carries the biggest normal gap between afternoon and dawn, 32°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Prosser.
Where Prosser Stands Nationally
Aridity defines the water calendar: about 9 inches in a normal year lands this among the driest tenth of ranked stations.
Prosser earns one nationally notable standing (outer quintile) against 6,860 NOAA 1991–2020 normals stations, middle-of-the-pack metrics stay silent here.
Monthly Precipitation
Average monthly rainfall
8.3 days with precipitation
5.9 days with precipitation
5.9 days with precipitation
5.2 days with precipitation
5.8 days with precipitation
3.7 days with precipitation
1.7 days with precipitation
1.5 days with precipitation
2.7 days with precipitation
5.7 days with precipitation
7.1 days with precipitation
8.3 days with precipitation
Prosser's wet season runs through the cold months
December, January and February carry 40% of the year's precipitation here, while June through August contribute 12%. That is the cool-season-dominant pattern of the West Coast and the higher inland West, where storm tracks swing south in winter and summer turns dry; the thermometer meanwhile shows a 42.1°F seasonal spread.
- Wettest month
- December, 1.3"
- Driest month
- August, 0.2"
- Wettest three months
- December, January, February (40% of the year)
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A cool-season label means the December-February share reaches 35%. Where snow falls, the monthly figures above report liquid-equivalent precipitation, so a wet winter month is not necessarily a rainy one.
Prosser is dry, and what does fall arrives gently
Only about 62 days a year record measurable precipitation here, 17% of the calendar, and they carry 8.7" between them. At roughly 0.14 inches on an average wet day, this is not the damp drizzle of a marine climate; it is an arid record in which precipitation is both uncommon and light when it appears.
The wettest month by count is January at about 8 wet days; the driest is August at about 2.
A low per-event average in a dry record is a statement about typical days only. Arid regions can still take a large share of a year's total from a single convective storm, which a normal cannot show.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, not the extremes within it.
Frost Dates & Growing Season
First Fall Freeze
October 22
50% probability date
Last Spring Freeze
April 14
50% probability date
Growing Season
191 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
5,172
Higher = more heating needed
Cooling Degree Days
839
Higher = more cooling needed
Warmest Month
July
Coldest Month
December
Nationwide similar cities
Other rankable U.S. places outside WA closest to Prosser on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (53°F here).
- Centerport, NY 53°F · 0.0°F off
- Emmitsburg, MD 53°F · 0.0°F off
- Glencoe, KY 53°F · 0.0°F off
- Goldfield, NV 53°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (8.7" here), excluding temperature-peer places.
- Montello -, NV 8.8" · 0.0" off
- Deming, NM 8.8" · 0.0" off
- Salida, CO 8.8" · 0.0" off
- El Paso, TX 8.8" · 0.0" off
Scarce-water calendar
Where Prosser's limited precipitation lands
heating led · dry · mid swing
Prosser's energy balance leans toward cold weather: 5,172 annual heating degree days against 839 for cooling. Its 42.1°F seasonal range still makes the monthly rows more useful than the annual average alone.
Prosser's frost-free season lasts about 191 days, a middle-length window whose endpoints matter more than the annual average. It describes freeze probability, not year-specific planting conditions.
July and December mark the typical warm and cold ends of the calendar in Prosser's middle-range seasonal profile. The measured spread is 42.1°F. The annual average is 53°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Prosser's cold-season load does not imply a wet climate. Annual precipitation is 8.7 inches, which places the station in PlainClimate's dry range. Snowfall is not added to the interpretation because its annual value is missing. The snowfall and rainfall fields should be read separately rather than inferred from temperature.
Prosser wettest normal
December
December concentrates the scarce annual total (8.7 inches).
Prosser driest normal
August
August is typically driest; arid stations are defined by when water is absent, not by a four-season grid.
Questions about Prosser's climate
How dry is Prosser? ▼
How many days above 90°F does Prosser get? ▼
How much energy does heating and cooling require in Prosser? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Prosser's primary station: PROSSER (USC00456768). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 5356450). Match rule for Prosser: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Prosser comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.