St. Joseph's Catholic Church · Photo: Montanasuffragettes · CC BY-SA 4.0Precipitation in Charlo trails that of 90% of U.S. towns: 19 inches a year
Nights in January average 21°. Since 1901–2000, the year has warmed by 1.3°, most of all in January. Homes need heating from October to April, the months averaging under 50°.
A year in Charlo at a glance
Each month’s typical high and low, and what it brings.
What stands out about Charlo’s climate
Compared with towns across the U.S., with Charlo’s place in Montana beside it.
What a year in Charlo feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 142 frost-free days a year
In half of years the last 32° night comes by May 12 and the first by October 2. Frost and day counts come from NOAA’s station at Saint Ignatius, MT, 10 miles from the town’s center, at about the same height.
The 2023 USDA map puts Charlo’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 34 inches of snow a winter
Snow, measured at Skq Dam, MT, falls mostly in December. Precipitation (rain plus melted snow) adds up to 19 inches a year; June is the wettest month and August the driest. Rain or snow falls on about 128 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Charlo
95% 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 Saint Ignatius, MT.
Living with Charlo’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
142 frost-free days in zone 6a. The last frost comes by May 12 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 2.
Months with highs of 62–84° and lows of 40° or more: May, June, August and September. 0.6 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Charlo from natural hazards, avalanches are the largest share (35%); heat waves, cold waves, winter storms and ice storms together are 20%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Charlo and similar climates
TownRatings has no climate map of the towns around Charlo yet.
Climates most like Charlo’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 |
|---|---|---|---|---|
| Charlo, MT | 21° | 84° | 19" | 34" |
| Cimarron Hills, CO | 18° | 85° | 17" | 33" |
| Edgewood, NM | 19° | 85° | 15" | 29" |
| Airway Heights, WA | 24° | 84° | 17" | 45" |
| Deschutes River Woods, OR | 24° | 84° | 13" | 22" |
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 Charlo averaged 1.3° warmer than the 1900s. The biggest change is in January (+3.9°).
A smaller shift than in 52% 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 Charlo compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Charlo’s place among Montana’s.
Charlo weather by month
Highs, lows and precipitation from NOAA’s grid at Charlo’s center; snow, wet days and snow on the ground from Skq Dam, MT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 33° | 21° | 1.3" | 8.4" | 13 | 18° – 34° |
| February | 38° | 22° | 1.2" | 4.2" | 10 | 19° – 37° |
| March | 49° | 28° | 1.4" | 5.0" | 12 | 31° – 44° |
| April | 57° | 34° | 1.8" | 0.9" | 12 | 40° – 52° |
| May | 67° | 41° | 2.3" | 0.0" | 12 | 49° – 59° |
| June | 74° | 48° | 2.8" | 0.0" | 13 | 57° – 69° |
| July | 84° | 53° | 1.0" | 0.0" | 7 | 59° – 76° |
| August | 84° | 52° | 0.9" | 0.0" | 6 | 63° – 71° |
| September | 73° | 44° | 1.3" | 0.0" | 8 | 55° – 64° |
| October | 57° | 35° | 1.8" | 0.7" | 11 | 39° – 52° |
| November | 41° | 27° | 1.6" | 4.7" | 13 | 27° – 41° |
| December | 33° | 21° | 1.5" | 9.7" | 13 | 21° – 33° |
| Year | 57° | 35° | 18.7" | 33.6" | 128 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 19° to 37°. August is the most reliable, staying within 8°.
Where Charlo’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 Charlo’s center.
- Snow: Skq Dam, MT.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Saint Ignatius, MT, 10 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 Charlo’s climate
What is the weather like in Charlo?
A typical July afternoon reaches 84°, a January night drops to 21°, and about 34 inches of snow falls in a normal winter. Colder January nights than 54% of U.S. towns; cooler July afternoons than 58% of U.S. towns.
How cold does it get in Charlo in winter?
January nights average 21°. About 152 nights a year reach 32° or below and 6 reach 0° or below. In the coldest January of the last 30 years the month averaged 18°.
How much snow does Charlo get?
About 34 inches in a normal winter at Skq Dam, MT, most of it in December.
How hot does it get in Charlo?
July, with a typical high of 84° and a low of 53°. About 20 days a year reach 90° (Saint Ignatius, MT).
When is the first and last frost in Charlo?
In half of years the last spring frost (32°) comes by May 12 and the first fall frost by October 2, about 142 frost-free days, at Saint Ignatius, MT.
What growing zone is Charlo 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 Charlo?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Charlo getting warmer?
Yes: 1991–2020 averaged 1.3° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 52% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Charlo.
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.