Tri-City’s winters are milder and less snowy than most of the U.S.
A typical July afternoon reaches 87°, a January night drops to 36°, and about 2 inches of snow falls in a normal winter.
A year in Tri-City at a glance
Each month’s typical high and low, and what it brings.
What stands out about Tri-City’s climate
Compared with towns across the U.S., with Tri-City’s place in Oregon beside it.
What a year in Tri-City feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 221 frost-free days a year
In half of years the last 32° night comes by March 31 and the first by November 6. Frost and day counts come from NOAA’s station at Riddle, OR, 4 miles from the town’s center, 250 ft lower.
The 2023 USDA map puts Tri-City’s center in zone 8b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 20°. 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 2 inches of snow a winter
Snow, measured at Riddle, OR, falls mostly in February. Precipitation (rain plus melted snow) adds up to 33 inches a year; December is the wettest month and July the driest. Rain or snow falls on about 147 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Tri-City
85% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from November 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 Riddle, OR.
Living with Tri-City’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
221 frost-free days in zone 8b. The last frost comes by Mar 31 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 6.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October. 4.9 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Tri-City from natural hazards, river flooding is the largest share (63%); heat waves, cold waves, winter storms and ice storms together are 2%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Tri-City and similar climates
TownRatings has no climate map of the towns around Tri-City yet.
Climates most like Tri-City’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 |
|---|---|---|---|---|
| Tri-City, OR | 36° | 87° | 33" | 1.9" |
| Calistoga, CA | 38° | 89° | 35" | 0.0" |
| Indian Trail, NC | 31° | 90° | 43" | 2.1" |
| York, SC | 31° | 90° | 44" | 3.5" |
| Hampton, VA | 32° | 89° | 47" | 2.7" |
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 Tri-City averaged 1.7° warmer than the 1900s. The biggest change is in January (+2.8°).
A bigger shift than in 75% 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 Tri-City compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Tri-City’s place among Oregon’s.
Tri-City weather by month
Highs, lows and precipitation from NOAA’s grid at Tri-City’s center; snow, wet days and snow on the ground from Riddle, OR. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 50° | 36° | 4.9" | 0.5" | 19 | 0 | 38° – 48° |
| February | 54° | 37° | 3.7" | 0.7" | 17 | 0 | 39° – 50° |
| March | 59° | 38° | 3.7" | 0.1" | 18 | 0 | 44° – 54° |
| April | 64° | 40° | 2.8" | 0.0" | 16 | 0 | 48° – 58° |
| May | 72° | 46° | 2.0" | 0.0" | 12 | 0 | 54° – 65° |
| June | 78° | 50° | 1.0" | 0.0" | 6 | 0 | 60° – 71° |
| July | 87° | 55° | 0.3" | 0.0" | 2 | 0 | 64° – 75° |
| August | 87° | 54° | 0.3" | 0.0" | 2 | 0 | 66° – 75° |
| September | 81° | 49° | 0.8" | 0.0" | 5 | 0 | 62° – 68° |
| October | 68° | 43° | 2.4" | 0.0" | 12 | 0 | 52° – 61° |
| November | 55° | 40° | 4.8" | 0.0" | 19 | 0 | 41° – 51° |
| December | 47° | 36° | 6.2" | 0.6" | 20 | 0 | 37° – 46° |
| Year | 67° | 43° | 32.8" | 1.9" | 147 | 1 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 39° to 50°. September is the most reliable, staying within 7°.
Where Tri-City’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 Tri-City’s center.
- Snow: Riddle, OR.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Riddle, OR, 4 miles from the town’s center, 250 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 Tri-City’s climate
What is the weather like in Tri-City?
A typical July afternoon reaches 87°, a January night drops to 36°, and about 2 inches of snow falls in a normal winter. Milder January nights than 83% of U.S. towns; hotter July afternoons than 62% of U.S. towns.
How cold does it get in Tri-City in winter?
December nights average 36°. About 33 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 37°.
How much snow does Tri-City get?
About 1.9 inches in a normal winter at Riddle, OR, most of it in February, with snow on the ground about 1 days a year.
How hot does it get in Tri-City?
July, with a typical high of 87° and a low of 55°. About 35 days a year reach 90° and 3 reach 100° (Riddle, OR).
When is the first and last frost in Tri-City?
In half of years the last spring frost (32°) comes by March 31 and the first fall frost by November 6, about 221 frost-free days, at Riddle, OR.
What growing zone is Tri-City in?
Zone 8b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 20°.
What is the best time of year to visit Tri-City?
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 Tri-City getting warmer?
Yes: 1991–2020 averaged 1.7° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 75% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Tri-City.
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.