Lewiston Historic District · Photo: Adrian Reed Smith (VivaLaPandaz) · CC BY-SA 3.0Lewiston reaches 100° on about 17 days a year, more than 94% of U.S. towns
In January the night’s low is typically 34°. The gap between a January night and a July afternoon is 60°. Winters are mild: January nights here are milder than in 79% of U.S. towns. Comfortable outdoor weather, highs of 66–76°, belongs to April, May and October.
A year in Lewiston at a glance
Each month’s typical high and low, and what it brings.
What stands out about Lewiston’s climate
Compared with towns across the U.S., with Lewiston’s place in California beside it.
What a year in Lewiston feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 178 frost-free days a year
In half of years the last 32° night comes by April 23 and the first by October 22. Frost and day counts come from NOAA’s station at Trinity Rvr Hatchery, CA, 2.5 miles from the town’s center, 450 ft lower.
The 2023 USDA map puts Lewiston’s center in zone 8b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 18°. 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 6 inches of snow a winter
Snow, measured at Trinity Rvr Hatchery, CA, falls mostly in December. Precipitation (rain plus melted snow) adds up to 46 inches a year; December is the wettest month and July the driest. Rain or snow falls on about 95 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Lewiston
83% of the work is heating. 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 Trinity Rvr Hatchery, CA.
Living with Lewiston’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
178 frost-free days in zone 8b. The last frost comes by Apr 23 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 22.
Months with highs of 62–84° and lows of 40° or more: April, May and October. 11 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Lewiston from natural hazards, wildfire is the largest share (53%). Normals are averages; the hazards page covers the extremes.
Natural hazards →Lewiston and similar climates
TownRatings has no climate map of the towns around Lewiston yet.
Climates most like Lewiston’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 |
|---|---|---|---|---|
| Lewiston, CA | 34° | 94° | 46" | 6.4" |
| Mount Pleasant, TX | 35° | 94° | 48" | 1.9" |
| Durant, OK | 32° | 94° | 43" | 2.0" |
| Cayce, SC | 35° | 93° | 46" | 1.2" |
| Milledgeville, GA | 34° | 93° | 47" | 0.6" |
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 Lewiston averaged 1.5° warmer than the 1900s. The biggest change is in September (+2.3°).
A bigger shift than in 60% 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 Lewiston compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Lewiston’s place among California’s.
Lewiston weather by month
Highs, lows and precipitation from NOAA’s grid at Lewiston’s center; snow, wet days and snow on the ground from Trinity Rvr Hatchery, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 50° | 34° | 7.8" | 1.2" | 15 | 0 | 37° – 47° |
| February | 55° | 35° | 7.6" | 1.6" | 12 | 0 | 39° – 51° |
| March | 60° | 37° | 6.8" | 0.3" | 13 | 0 | 41° – 55° |
| April | 66° | 40° | 3.4" | 0.0" | 10 | 0 | 48° – 58° |
| May | 76° | 46° | 2.0" | 0.0" | 8 | 0 | 53° – 68° |
| June | 85° | 52° | 0.9" | 0.0" | 3 | 0 | 63° – 76° |
| July | 94° | 59° | 0.1" | 0.0" | 1 | 0 | 71° – 80° |
| August | 93° | 57° | 0.2" | 0.0" | 1 | 0 | 72° – 80° |
| September | 88° | 51° | 0.4" | 0.0" | 2 | 0 | 66° – 74° |
| October | 74° | 44° | 2.5" | 0.0" | 5 | 0 | 55° – 64° |
| November | 57° | 38° | 5.1" | 0.6" | 11 | 0 | 39° – 53° |
| December | 48° | 34° | 8.9" | 2.7" | 15 | 1 | 38° – 46° |
| Year | 70° | 44° | 45.6" | 6.4" | 95 | 1 |
How much a month can swing
A normal is an average. May swings the most: from 1991 to 2020 its average ranged from 53° to 68°. September is the most reliable, staying within 7°.
Where Lewiston’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 Lewiston’s center.
- Snow: Trinity Rvr Hatchery, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Trinity Rvr Hatchery, CA, 2.5 miles from the town’s center, 450 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 Lewiston’s climate
What is the weather like in Lewiston?
A typical July afternoon reaches 94°, a January night drops to 34°, and about 6 inches of snow falls in a normal winter. Milder January nights than 79% of U.S. towns; hotter July afternoons than 93% of U.S. towns.
How cold does it get in Lewiston in winter?
December nights average 34°. About 78 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 38°.
How much snow does Lewiston get?
About 6.4 inches in a normal winter at Trinity Rvr Hatchery, CA, most of it in December, with snow on the ground about 1 days a year.
How hot does it get in Lewiston?
July, with a typical high of 94° and a low of 59°. About 78 days a year reach 90° and 17 reach 100° (Trinity Rvr Hatchery, CA).
When is the first and last frost in Lewiston?
In half of years the last spring frost (32°) comes by April 23 and the first fall frost by October 22, about 178 frost-free days, at Trinity Rvr Hatchery, CA.
What growing zone is Lewiston in?
Zone 8b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 18°.
What is the best time of year to visit Lewiston?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Lewiston getting warmer?
Yes: 1991–2020 averaged 1.5° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 60% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Lewiston.
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.