Photo: Williamborg 18:11, 24 May 2008 (UTC) · Public domainMattawa reaches 100° on about 11 days a year, more than 91% of U.S. towns
The coldest hours of a January night bottom out at 26° on average. By precipitation alone, it ranks drier than almost every U.S. town. Decade by decade the climate has edged up, 0.9° above 1901–2000. Garden chairs stay out from April to June and September to October, the months with highs of 65–82°.
A year in Mattawa at a glance
Each month’s typical high and low, and what it brings.
What stands out about Mattawa’s climate
Compared with towns across the U.S., with Mattawa’s place in Washington beside it.
What a year in Mattawa feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 222 frost-free days a year
In half of years the last 32° night comes by March 24 and the first by November 4. Frost and day counts come from NOAA’s station at Priest Rapids Dam, WA, 6 miles from the town’s center, 330 ft lower.
The 2023 USDA map puts Mattawa’s center in zone 7b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 6°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 7 inches of rain a year
December is the wettest month and August the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Mattawa
78% of the work is heating. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Priest Rapids Dam, WA.
Living with Mattawa’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
222 frost-free days in zone 7b. The last frost comes by Mar 24 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 4.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October. 0.1 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Mattawa from natural hazards, river flooding is the largest share (58%); heat waves, cold waves, winter storms and ice storms together are 19%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Mattawa and similar climates
TownRatings has no climate map of the towns around Mattawa yet.
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Mattawa averaged 0.9° warmer than the 1900s. The biggest change is in January (+3.3°).
A smaller shift than in 84% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Mattawa compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Mattawa’s place among Washington’s.
Mattawa weather by month
Highs, lows and precipitation from NOAA’s grid at Mattawa’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 39° | 26° | 1.0" | 24° – 38° |
| February | 46° | 29° | 0.7" | 27° – 44° |
| March | 57° | 34° | 0.6" | 39° – 51° |
| April | 65° | 40° | 0.5" | 48° – 59° |
| May | 75° | 48° | 0.6" | 57° – 66° |
| June | 82° | 55° | 0.5" | 64° – 76° |
| July | 91° | 61° | 0.2" | 69° – 80° |
| August | 89° | 59° | 0.1" | 69° – 77° |
| September | 80° | 51° | 0.2" | 62° – 69° |
| October | 65° | 40° | 0.5" | 48° – 58° |
| November | 49° | 32° | 0.8" | 34° – 46° |
| December | 39° | 26° | 1.2" | 26° – 37° |
| Year | 65° | 42° | 7.0" |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 27° to 44°. September is the most reliable, staying within 7°.
Where Mattawa’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Mattawa’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Priest Rapids Dam, WA, 6 miles from the town’s center, 330 ft lower; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Mattawa’s climate
What is the weather like in Mattawa?
A typical July afternoon reaches 91°, a January night drops to 26°. Milder January nights than 67% of U.S. towns; hotter July afternoons than 80% of U.S. towns.
How cold does it get in Mattawa in winter?
January nights average 26°. About 75 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 24°.
How hot does it get in Mattawa?
July, with a typical high of 91° and a low of 61°. About 50 days a year reach 90° and 11 reach 100° (Priest Rapids Dam, WA).
When is the first and last frost in Mattawa?
In half of years the last spring frost (32°) comes by March 24 and the first fall frost by November 4, about 222 frost-free days, at Priest Rapids Dam, WA.
What growing zone is Mattawa in?
Zone 7b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 6°.
What is the best time of year to visit Mattawa?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, June, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Mattawa getting warmer?
Yes: 1991–2020 averaged 0.9° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 84% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Mattawa.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.