Photo: Travellers & Tinkers · CC BY-SA 4.0Few U.S. towns have colder winter nights than Circle
July afternoons average 86°. The year swings widely: the coldest month’s nights and the warmest month’s afternoons are 82° apart. Its yearly precipitation falls short of 94% of U.S. towns. Seedlings are safe outdoors from about May 17, with the first autumn frost due around September 22.
A year in Circle at a glance
Each month’s typical high and low, and what it brings.
What stands out about Circle’s climate
Compared with towns across the U.S., with Circle’s place in Montana beside it.
What a year in Circle feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 126 frost-free days a year
In half of years the last 32° night comes by May 17 and the first by September 22. Frost and day counts come from NOAA’s station at Circle, MT, 0.6 miles from the town’s center, at about the same height.
The 2023 USDA map puts Circle’s center in zone 4a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −29°. 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 14 inches of rain a year
June is the wettest month and January the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Circle
93% 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 Circle, MT.
Living with Circle’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
126 frost-free days in zone 4a. The last frost comes by May 17 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 22.
Months with highs of 62–84° and lows of 40° or more: June and September. 0.4 miles of trails are waiting.
Parks & trails →Cold waves are 50% of the yearly building losses FEMA expects in Circle from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →Circle and similar climates
TownRatings has no climate map of the towns around Circle yet.
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 Circle averaged 1.3° warmer than the 1900s. The biggest change is in January (+3.7°).
A smaller shift than in 56% 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 Circle compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Circle’s place among Montana’s.
Circle weather by month
Highs, lows and precipitation from NOAA’s grid at Circle’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 26° | 4° | 0.3" | 2° – 30° |
| February | 31° | 8° | 0.3" | −3° – 32° |
| March | 45° | 19° | 0.4" | 15° – 43° |
| April | 57° | 29° | 1.2" | 38° – 48° |
| May | 68° | 39° | 2.6" | 49° – 60° |
| June | 77° | 49° | 2.6" | 58° – 68° |
| July | 86° | 54° | 2.1" | 61° – 77° |
| August | 85° | 53° | 1.3" | 63° – 75° |
| September | 73° | 43° | 1.3" | 52° – 65° |
| October | 58° | 30° | 1.0" | 36° – 50° |
| November | 41° | 18° | 0.4" | 18° – 40° |
| December | 30° | 8° | 0.4" | 6° – 28° |
| Year | 56° | 30° | 13.8" |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from -3° to 32°. June is the most reliable, staying within 10°.
Where Circle’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 Circle’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Circle, MT, 0.6 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 Circle’s climate
What is the weather like in Circle?
A typical July afternoon reaches 86°, a January night drops to 4°. Colder January nights than all but 167 U.S. towns; hotter July afternoons than 54% of U.S. towns.
How cold does it get in Circle in winter?
January nights average 4°. About 183 nights a year reach 32° or below and 30 reach 0° or below. In the coldest January of the last 30 years the month averaged 2°.
How hot does it get in Circle?
July, with a typical high of 86° and a low of 54°. About 32 days a year reach 90° and 3 reach 100° (Circle, MT).
When is the first and last frost in Circle?
In half of years the last spring frost (32°) comes by May 17 and the first fall frost by September 22, about 126 frost-free days, at Circle, MT.
What growing zone is Circle in?
Zone 4a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −29°.
What is the best time of year to visit Circle?
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 Circle getting warmer?
Yes: 1991–2020 averaged 1.3° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 56% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Circle.
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.