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Weather & Climate in Prosser, WA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Prosser experiences four distinct seasons with an average annual temperature of 53°F (12°C). Winters average 34°F in January while summers reach 75°F in July. The area gets 279 sunny days per year, well above the U.S. average of 205 / making it one of the sunnier locations in the country. Annual precipitation totals 8.7 inches (drier than the 38-inch national average). Air quality is rated Good with a median AQI of 28 / among the cleanest air in the country. The city sits at an elevation of 659 feet.
Temperature
34°F Jan (1°C)
75°F Jul (24°C)
| Annual Average | 53.0°F |
| 2% below US avg | |
| January Average | 34°F (1°C) |
| July Average | 75°F (24°C) |
| Sunny Days | 279 days/yr |
Geography
| Elevation | 659 ft (201 m) |
| Area | 4.5 sq mi (11.7 km²) |
| Population Density | 1,202/sq mi |
| Coordinates | 46.2090°N, 119.7677°W |
| Timezone | America/Los_Angeles |
| County | Benton County County |
| Nearest Airport | Tri-Cities (PSC) 31 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 28.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 87.1 / 100 |
| Social Vulnerability | 30.3 / 100 |
| Community Resilience | 58.6 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Relatively Moderate |
| Wildfire | Relatively Moderate |
| Flood | Relatively Moderate |
| Hail | Relatively Low |
| Strong Wind | Relatively Low |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively High |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively High |
| Drought | Very Low |
| Cold Wave | Relatively Moderate |
| Landslide | Relatively Low |
| Volcano | Very Low |
| Avalanche | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
232 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.3.
| Nov 28, 1991 | 7 km S of Walla Walla East, Washington | M4.3 | 115 km | 9 km |
| Jun 17, 2010 | 30 km S of White Swan, Washington | M4.2 | 76 km | 3 km |
| Feb 18, 2015 | 15 km ENE of Cle Elum, Washington | M4.2 | 138 km | 4 km |
| Jan 30, 2000 | 6 km SE of Condon, Oregon | M4.1 | 116 km | -1 km |
| Jul 14, 1992 | 6 km S of Walla Walla East, Washington | M4.1 | 115 km | 11 km |
| Aug 16, 2004 | 16 km ENE of Packwood, Washington | M4.0 | 141 km | -1 km |
| Oct 9, 1998 | 20 km S of White Swan, Washington | M4.0 | 72 km | 2 km |
| Mar 22, 1997 | 10 km ESE of Condon, Oregon | M3.9 | 115 km | 0 km |
| Aug 7, 1992 | 8 km WSW of Irrigon, Oregon | M3.9 | 41 km | 0 km |
| Nov 18, 1997 | 20 km NW of Bickleton, Washington | M3.9 | 55 km | 15 km |
| Mar 29, 2010 | 10 km NE of Cliffdell, Washington | M3.8 | 127 km | 1 km |
| Jan 1, 1997 | 14 km NNE of Selah, Washington | M3.7 | 82 km | 18 km |
| Sep 4, 2011 | 14 km N of Richland, Washington | M3.7 | 45 km | 2 km |
| May 18, 2008 | 11 km SSW of Benton City, Washington | M3.7 | 17 km | 20 km |
| Feb 1, 2000 | 7 km SE of Condon, Oregon | M3.6 | 116 km | -1 km |
| Jan 23, 2015 | 3 km N of Cayuse, Oregon | M3.5 | 109 km | 20 km |
| Oct 26, 1992 | 12 km N of Naches, Washington | M3.5 | 101 km | -1 km |
| Aug 31, 1999 | Washington-Oregon border region | M3.5 | 117 km | 3 km |
| Jun 29, 2005 | 0 km SE of Gleed, Washington | M3.5 | 82 km | 9 km |
| Oct 12, 2017 | 25 km NW of Bickleton, Washington | M3.4 | 60 km | 13 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
26 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2.
| Date | Rating | Distance | Path | Fatalities |
| Jun 26, 1958 | EF2 | 66 km | 0.3 mi | 0 |
| Apr 30, 1957 | EF2 | 71 km | 1.0 mi | 0 |
| May 19, 2006 | EF1 | 43 km | 0.1 mi | 0 |
| Apr 23, 1983 | EF1 | 69 km | 3.0 mi | 0 |
| Jul 1, 1978 | EF1 | 93 km | 2.3 mi | 0 |
| May 1, 2024 | EF0 | 98 km | 0.4 mi | 0 |
| Mar 31, 2020 | EF0 | 40 km | 0.1 mi | 0 |
| May 22, 2016 | EF0 | 46 km | 0.2 mi | 0 |
| Aug 13, 2014 | EF0 | 13 km | 0.3 mi | 0 |
| Apr 14, 2011 | EF0 | 88 km | 0.2 mi | 0 |
| Apr 7, 2008 | EF0 | 73 km | 0.1 mi | 0 |
| May 9, 2005 | EF0 | 71 km | 0.2 mi | 0 |
| Apr 23, 2005 | EF0 | 42 km | 0.1 mi | 0 |
| Apr 23, 2005 | EF0 | 45 km | 0.1 mi | 0 |
| Jun 7, 2004 | EF0 | 20 km | 0.5 mi | 0 |
| May 23, 2004 | EF0 | 64 km | 0.1 mi | 0 |
| Jul 13, 2002 | EF0 | 92 km | 0.2 mi | 0 |
| May 15, 2000 | EF0 | 46 km | 0.2 mi | 0 |
| May 9, 1999 | EF0 | 83 km | — | 0 |
| Aug 26, 1997 | EF0 | 76 km | 1.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Nearby Volcanoes
6 volcanoes within 200 km. Closest: Adams (133 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Adams | Stratovolcano | 3,742 m (12,277 ft) | 950 | 133 km |
| Indian Heaven | Shield(s) | 1,806 m (5,925 ft) | -6250 | 161 km |
| Rainier | Stratovolcano | 4,392 m (14,409 ft) | 1450 | 168 km |
| Hood | Stratovolcano | 3,426 m (11,240 ft) | 1866 | 176 km |
| West Crater | Volcanic field | 1,329 m (4,360 ft) | -5750 | 182 km |
| St. Helens | Stratovolcano | 2,549 m (8,363 ft) | 2008 | 186 km |
Source: Smithsonian Institution Global Volcanism Program (GVP).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: RANGE 12 (167,604 acres, 2016).
| Year | Name | Acres Burned | Distance |
| 2016 | RANGE 12 | 167,604 | 33 km |
| 2000 | 24 COMMAND | 162,300 | 29 km |
| 1984 | HANFORD | 122,914 | 29 km |
| 2000 | MULE DRY | 90,184 | 38 km |
| 2007 | WAUTOMA | 77,956 | 31 km |
| 2020 | EVANS CANYON | 76,288 | 96 km |
| 1996 | COLD CREEK | 72,859 | 57 km |
| 2018 | BOYLSTON | 66,292 | 76 km |
| 2023 | NEWELL ROAD | 61,833 | 59 km |
| 2024 | BIG HORN | 51,023 | 46 km |
| 2009 | DRY CREEK COMPLEX | 49,843 | 33 km |
| 2008 | COAL PLANT | 45,801 | 58 km |
| 2019 | COLD CREEK | 43,756 | 31 km |
| 2015 | HIGHWAY 8 | 35,296 | 56 km |
| 2003 | UMTANUM RIDGE | 34,351 | 58 km |
| 2016 | 0353 RN SCOTT CANYON | 32,051 | 94 km |
| 2017 | SILVER DOLLAR | 30,789 | 40 km |
| 2022 | VANTAGE HIGHWAY | 29,299 | 93 km |
| 2007 | HORSE HEAVEN COMPLEX (SIX PRONG) | 28,225 | 47 km |
| 2000 | UNNAMED | 27,815 | 91 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 34°F (1°C) | 1.0 in | |
| February | 37°F (3°C) | 0.8 in | |
| March | 45°F (7°C) | 0.8 in | |
| April | 51°F (11°C) | 0.6 in | |
| May | 59°F (15°C) | 0.6 in | |
| June | 66°F (19°C) | 0.4 in | |
| July | 75°F (24°C) | 0.2 in | Warmest, Driest |
| August | 71°F (22°C) | 0.3 in | |
| September | 62°F (17°C) | 0.4 in | |
| October | 51°F (11°C) | 0.6 in | |
| November | 40°F (4°C) | 1.1 in | |
| December | 32°F (-0°C) | 1.1 in | Coldest, Wettest |
Prosser has a seasonal temperature swing of 43°F / from 32°F in December to 75°F in July. Total annual precipitation is 7.9 inches, with December being the wettest month (1.1") and July the driest (0.2").