Photo: Royalbroil · CC BY-SA 3.0Less rain and snow falls on Eureka than on 93% of U.S. towns: 15 inches a year
Nights in January average 18°. Rain follows the seasons: June brings about 3.3 times as much as February. By January nights alone, it runs colder than 71% of U.S. towns. Garden chairs stay out from May to September, the months with highs of 68–84°.
A year in Eureka at a glance
Each month’s typical high and low, and what it brings.
What stands out about Eureka’s climate
Compared with towns across the U.S., with Eureka’s place in Montana beside it.
What a year in Eureka feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 138 frost-free days a year
In half of years the last 32° night comes by May 11 and the first by September 27. Frost and day counts come from NOAA’s station at Eureka Rs, MT, 1.5 miles from the town’s center, 120 ft lower.
The 2023 USDA map puts Eureka’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −13°. 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 35 inches of snow a winter
Snow, measured at Eureka Rs, MT, falls mostly in December. Precipitation (rain plus melted snow) adds up to 15 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 103 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Eureka
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 Eureka Rs, MT.
Living with Eureka’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
138 frost-free days in zone 5b. The last frost comes by May 11 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 27.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 1.5 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Eureka from natural hazards, river flooding is the largest share (44%); heat waves, cold waves, winter storms and ice storms together are 24%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Eureka and similar climates
TownRatings has no climate map of the towns around Eureka yet.
Climates most like Eureka’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 |
|---|---|---|---|---|
| Eureka, MT | 18° | 84° | 15" | 35" |
| Cimarron Hills, CO | 18° | 85° | 17" | 33" |
| Los Alamos, NM | 19° | 85° | 15" | 42" |
| Cody, WY | 14° | 85° | 11" | 45" |
| Doney Park, AZ | 17° | 86° | 16" | 52" |
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 Eureka averaged 1.8° warmer than the 1900s. The biggest change is in January (+4.3°).
A bigger shift than in 82% 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 Eureka compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Eureka’s place among Montana’s.
Eureka weather by month
Highs, lows and precipitation from NOAA’s grid at Eureka’s center; snow, wet days and snow on the ground from Eureka Rs, MT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 31° | 18° | 0.9" | 8.5" | 11 | 20 | 14° – 31° |
| February | 37° | 19° | 0.7" | 5.9" | 8 | 11 | 14° – 36° |
| March | 48° | 26° | 0.9" | 3.7" | 9 | 5 | 29° – 42° |
| April | 58° | 32° | 1.0" | 1.0" | 9 | 1 | 40° – 53° |
| May | 68° | 40° | 1.8" | 0.2" | 10 | 0 | 49° – 60° |
| June | 74° | 46° | 2.4" | 0.0" | 10 | 0 | 57° – 67° |
| July | 84° | 51° | 1.1" | 0.0" | 7 | 0 | 59° – 73° |
| August | 84° | 49° | 0.9" | 0.0" | 5 | 0 | 62° – 69° |
| September | 72° | 41° | 1.2" | 0.0" | 7 | 0 | 52° – 62° |
| October | 56° | 33° | 1.2" | 0.6" | 9 | 1 | 39° – 50° |
| November | 40° | 26° | 1.3" | 5.0" | 9 | 4 | 25° – 40° |
| December | 30° | 19° | 1.1" | 10.2" | 10 | 15 | 17° – 30° |
| Year | 57° | 33° | 14.6" | 35.1" | 103 | 56 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 14° to 36°. August is the most reliable, staying within 7°.
Where Eureka’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 Eureka’s center.
- Snow: Eureka Rs, MT (NOAA station in town).
- Frost, freezing nights, 90° and 100° days, heating and cooling: Eureka Rs, MT, 1.5 miles from the town’s center, 120 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 Eureka’s climate
What is the weather like in Eureka?
A typical July afternoon reaches 84°, a January night drops to 18°, and about 35 inches of snow falls in a normal winter. Colder January nights than 71% of U.S. towns; cooler July afternoons than 60% of U.S. towns.
How cold does it get in Eureka in winter?
January nights average 18°. About 153 nights a year reach 32° or below and 9 reach 0° or below. In the coldest January of the last 30 years the month averaged 14°.
How much snow does Eureka get?
About 35 inches in a normal winter at Eureka Rs, MT, most of it in December, with snow on the ground about 56 days a year.
How hot does it get in Eureka?
July, with a typical high of 84° and a low of 51°. About 26 days a year reach 90° and 2 reach 100° (Eureka Rs, MT).
When is the first and last frost in Eureka?
In half of years the last spring frost (32°) comes by May 11 and the first fall frost by September 27, about 138 frost-free days, at Eureka Rs, MT.
What growing zone is Eureka in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −13°.
What is the best time of year to visit Eureka?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Eureka getting warmer?
Yes: 1991–2020 averaged 1.8° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 82% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Eureka.
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.