Ryan House · Photo: Joe Mabel · CC BY-SA 3.0Few U.S. towns have cooler summers than Sumner
In January the night’s low is typically 35°. Winters are mild: January nights here are milder than in 81% of U.S. towns. Compared with 1901–2000, the average now sits 1.1° higher. For walks and days out, the stretch from May to September brings highs of 66–78°.
A year in Sumner at a glance
Each month’s typical high and low, and what it brings.
What stands out about Sumner’s climate
Compared with towns across the U.S., with Sumner’s place in Washington beside it.
What a year in Sumner feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 250 frost-free days a year
In half of years the last 32° night comes by March 8 and the first by November 14. Frost and day counts come from NOAA’s station at Tacoma #1, WA, 8 miles from the town’s center, at about the same height.
The 2023 USDA map puts Sumner’s center in zone 8b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 19°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
About 6 inches of snow a winter
Snow, measured at Mcmillin Reservoir, WA, falls mostly in January, November and December. Precipitation (rain plus melted snow) adds up to 40 inches a year; November is the wettest month and July the driest. Rain or snow falls on about 166 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Sumner
95% of the work is heating, so the furnace matters far more than the air conditioner. 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 Tacoma #1, WA.
Living with Sumner’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
250 frost-free days in zone 8b. The last frost comes by Mar 8 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 14.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 3.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Sumner from natural hazards, earthquakes are the largest share (70%); heat waves, cold waves, winter storms and ice storms together are 1%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Sumner and its neighbors
Every town next door is within a degree of Sumner in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Sumner’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Sumner, WA | 35° | 77° | 40" | 5.6" |
| Silverton, OR | 36° | 81° | 46" | 1.1" |
| Scotts Valley, CA | 39° | 79° | 37" | 0.0" |
| Nantucket, MA | 26° | 76° | 44" | 25" |
| Brigantine, NJ | 28° | 83° | 45" | 10" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Sumner averaged 1.1° warmer than the 1900s. The biggest change is in January (+2.6°).
A smaller shift than in 74% 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 Sumner compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Sumner’s place among Washington’s.
Sumner weather by month
Highs, lows and precipitation from NOAA’s grid at Sumner’s center; snow, wet days and snow on the ground from Mcmillin Reservoir, WA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 47° | 35° | 5.5" | 1.5" | 20 | 2 | 36° – 46° |
| February | 50° | 35° | 3.8" | 0.5" | 15 | 0 | 35° – 48° |
| March | 54° | 38° | 4.2" | 0.6" | 20 | 1 | 42° – 50° |
| April | 60° | 41° | 3.5" | 0.0" | 16 | 0 | 45° – 56° |
| May | 66° | 47° | 2.3" | 0.0" | 13 | 0 | 52° – 60° |
| June | 71° | 51° | 1.9" | 0.0" | 11 | 0 | 58° – 66° |
| July | 77° | 55° | 0.7" | 0.0" | 5 | 0 | 61° – 69° |
| August | 78° | 55° | 0.9" | 0.0" | 5 | 0 | 63° – 70° |
| September | 71° | 51° | 1.7" | 0.0" | 8 | 0 | 58° – 64° |
| October | 61° | 44° | 3.9" | 0.0" | 15 | 0 | 49° – 57° |
| November | 52° | 38° | 6.1" | 1.5" | 19 | 1 | 41° – 50° |
| December | 46° | 35° | 5.5" | 1.5" | 20 | 2 | 36° – 43° |
| Year | 61° | 44° | 40.0" | 5.6" | 166 | 5 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 35° to 48°. September is the most reliable, staying within 7°.
Where Sumner’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 Sumner’s center.
- Snow: Mcmillin Reservoir, WA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Tacoma #1, WA, 8 miles from the town’s center, at about the same height; 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 Sumner’s climate
What is the weather like in Sumner?
A typical July afternoon reaches 77°, a January night drops to 35°, and about 6 inches of snow falls in a normal winter. Milder January nights than 81% of U.S. towns; cooler July afternoons than 97% of U.S. towns.
How cold does it get in Sumner in winter?
December nights average 35°. About 27 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 36°.
How much snow does Sumner get?
About 5.6 inches in a normal winter at Mcmillin Reservoir, WA, most of it in January, November and December, with snow on the ground about 5 days a year.
How hot does it get in Sumner?
July, with a typical high of 77°. 90° days are rare: none in a normal year at Tacoma #1, WA.
When is the first and last frost in Sumner?
In half of years the last spring frost (32°) comes by March 8 and the first fall frost by November 14, about 250 frost-free days, at Tacoma #1, WA.
What growing zone is Sumner in?
Zone 8b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 19°.
What is the best time of year to visit Sumner?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Sumner getting warmer?
Yes: 1991–2020 averaged 1.1° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 74% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Sumner.
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.