Photo: Ntsimp · Public domainPrecipitation in Charleston trails that of 94% of U.S. towns: 14 inches a year
Peak summer warmth arrives in July, with afternoons near 89°. A year here swings 76° from midwinter lows to midsummer highs. In January, nights here are colder than in 90% of U.S. towns. For walks and days out, June and September bring highs of 78–81°.
A year in Charleston at a glance
Each month’s typical high and low, and what it brings.
What stands out about Charleston’s climate
Compared with towns across the U.S., with Charleston’s place in Utah beside it.
What a year in Charleston feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 106 frost-free days a year
In half of years the last 32° night comes by June 4 and the first by September 20. Frost and day counts come from NOAA’s station at Heber, UT, 2.3 miles from the town’s center, at about the same height.
The 2023 USDA map puts Charleston’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −9°. 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 75 inches of snow a winter
Snow, measured at Heber, UT, falls mostly in January. Precipitation (rain plus melted snow) adds up to 14 inches a year; January is the wettest month and July the driest. Rain or snow falls on about 88 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Charleston
96% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Heber, UT.
Living with Charleston’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
106 frost-free days in zone 6a. The last frost comes by Jun 4 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Sep 20.
Months with highs of 62–84° and lows of 40° or more: June and September. 5.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Charleston from natural hazards, river flooding is the largest share (60%); heat waves, cold waves, winter storms and ice storms together are 6%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Charleston and its neighbors
Every town next door is within a degree of Charleston in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Charleston’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 |
|---|---|---|---|---|
| Charleston, UT | 13° | 89° | 14" | 75" |
| Casper, WY | 15° | 89° | 12" | 82" |
| Thornton, CO | 18° | 90° | 14" | 74" |
| Billings, MT | 15° | 89° | 14" | 48" |
| Chadron, NE | 14° | 89° | 18" | 50" |
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 Charleston averaged 1.7° warmer than the 1900s. The biggest change is in March (+3.2°).
A bigger shift than in 69% 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 Charleston compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Charleston’s place among Utah’s.
Charleston weather by month
Highs, lows and precipitation from NOAA’s grid at Charleston’s center; snow, wet days and snow on the ground from Heber, UT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 36° | 13° | 1.5" | 21.5" | 9 | 24 | 17° – 31° |
| February | 41° | 16° | 1.3" | 13.9" | 8 | 21 | 23° – 36° |
| March | 51° | 25° | 1.1" | 6.7" | 8 | 7 | 32° – 43° |
| April | 59° | 30° | 1.3" | 4.0" | 9 | 0 | 40° – 50° |
| May | 70° | 37° | 1.5" | 0.8" | 8 | 0 | 48° – 57° |
| June | 81° | 44° | 0.8" | 0.0" | 6 | 0 | 56° – 67° |
| July | 89° | 51° | 0.7" | 0.0" | 5 | 0 | 63° – 74° |
| August | 87° | 50° | 0.9" | 0.0" | 6 | 0 | 64° – 72° |
| September | 78° | 41° | 1.2" | 0.0" | 6 | 0 | 56° – 63° |
| October | 64° | 31° | 1.4" | 1.7" | 7 | 0 | 40° – 52° |
| November | 49° | 22° | 1.2" | 8.6" | 7 | 5 | 27° – 42° |
| December | 37° | 14° | 1.3" | 17.8" | 8 | 18 | 20° – 31° |
| Year | 62° | 31° | 14.2" | 75.0" | 88 | 75 |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 27° to 42°. September is the most reliable, staying within 7°.
Where Charleston’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 Charleston’s center.
- Snow: Heber, UT.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Heber, UT, 2.3 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 Charleston’s climate
What is the weather like in Charleston?
A typical July afternoon reaches 89°, a January night drops to 13°, and about 75 inches of snow falls in a normal winter. Colder January nights than 90% of U.S. towns; hotter July afternoons than 72% of U.S. towns.
How cold does it get in Charleston in winter?
January nights average 13°. About 181 nights a year reach 32° or below and 10 reach 0° or below. In the coldest January of the last 30 years the month averaged 17°.
How much snow does Charleston get?
About 75 inches in a normal winter at Heber, UT, most of it in January, with snow on the ground about 75 days a year.
How hot does it get in Charleston?
July, with a typical high of 89° and a low of 51°. About 39 days a year reach 90° and 1 reach 100° (Heber, UT).
When is the first and last frost in Charleston?
In half of years the last spring frost (32°) comes by June 4 and the first fall frost by September 20, about 106 frost-free days, at Heber, UT.
What growing zone is Charleston in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −9°.
What is the best time of year to visit Charleston?
By one simple rule (highs of 62–84° and lows of 40° or more), June and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Charleston getting warmer?
Yes: 1991–2020 averaged 1.7° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 69% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Charleston.
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.