Dry weather: only 19 inches of rain and melted snow a year in Lake Mary Ronan, less than in 90% of U.S. towns
January mornings start at about 20°. In July, afternoons here are cooler than in 84% of U.S. towns. Decade by decade the climate has edged up, 1.2° above 1901–2000. From June to September, highs of 69–82° make it easy to spend the day outdoors.
A year in Lake Mary Ronan at a glance
Each month’s typical high and low, and what it brings.
What stands out about Lake Mary Ronan’s climate
Compared with towns across the U.S., with Lake Mary Ronan’s place in Montana beside it.
What a year in Lake Mary Ronan feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 165 frost-free days a year
In half of years the last 32° night comes by May 1 and the first by October 15. Frost and day counts come from Bigfork 13 S, MT, 16 miles away.
The 2023 USDA map puts Lake Mary Ronan’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −12°. 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 Lake Mary Ronan
97% 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 Bigfork 13 S, MT.
Living with Lake Mary Ronan’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
165 frost-free days in zone 5b. The last frost comes by May 1 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 15.
Months with highs of 62–84° and lows of 40° or more: June, July, August and September. 1.8 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Lake Mary Ronan from natural hazards, avalanches are the largest share (46%); heat waves, cold waves, winter storms and ice storms together are 7%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Lake Mary Ronan and similar climates
TownRatings has no climate map of the towns around Lake Mary Ronan yet.
Climates most like Lake Mary Ronan’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 |
|---|---|---|---|---|
| Lake Mary Ronan, MT | 20° | 82° | 19" | 34" |
| Ruidoso, NM | 22° | 82° | 20" | 26" |
| Pullman, WA | 27° | 84° | 20" | 33" |
| Cimarron Hills, CO | 18° | 85° | 17" | 33" |
| 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 Lake Mary Ronan averaged 1.2° warmer than the 1900s. The biggest change is in January (+3.7°).
A smaller 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 Lake Mary Ronan compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Lake Mary Ronan’s place among Montana’s.
Lake Mary Ronan weather by month
Highs, lows and precipitation from NOAA’s grid at Lake Mary Ronan’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 | 31° | 20° | 1.7" | 8.4" | 13 | 16° – 33° |
| February | 36° | 21° | 1.6" | 4.2" | 10 | 15° – 35° |
| March | 45° | 26° | 1.3" | 5.0" | 12 | 27° – 41° |
| April | 53° | 32° | 1.4" | 0.9" | 12 | 38° – 49° |
| May | 64° | 39° | 1.9" | 0.0" | 12 | 46° – 56° |
| June | 70° | 46° | 2.5" | 0.0" | 13 | 54° – 66° |
| July | 82° | 51° | 1.0" | 0.0" | 7 | 57° – 74° |
| August | 81° | 50° | 0.9" | 0.0" | 6 | 61° – 69° |
| September | 69° | 43° | 1.3" | 0.0" | 8 | 53° – 62° |
| October | 53° | 34° | 1.9" | 0.7" | 11 | 37° – 49° |
| November | 38° | 26° | 1.9" | 4.7" | 13 | 25° – 38° |
| December | 31° | 20° | 1.8" | 9.7" | 13 | 19° – 31° |
| Year | 54° | 34° | 18.9" | 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 15° to 35°. August is the most reliable, staying within 9°.
Where Lake Mary Ronan’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 Lake Mary Ronan’s center.
- Snow: Skq Dam, MT.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Bigfork 13 S, MT, 16 miles from the town’s center, 780 ft lower; no station nearby passes every check; this is the nearest one in the same valley, flagged above.
- 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 Lake Mary Ronan’s climate
What is the weather like in Lake Mary Ronan?
A typical July afternoon reaches 82°, a January night drops to 20°, and about 34 inches of snow falls in a normal winter. Colder January nights than 57% of U.S. towns; cooler July afternoons than 84% of U.S. towns.
How cold does it get in Lake Mary Ronan in winter?
January nights average 20°. About 127 nights a year reach 32° or below and 2 reach 0° or below. In the coldest January of the last 30 years the month averaged 16°.
How much snow does Lake Mary Ronan get?
About 34 inches in a normal winter at Skq Dam, MT, most of it in December.
How hot does it get in Lake Mary Ronan?
July, with a typical high of 82° and a low of 51°. About 5 days a year reach 90° (Bigfork 13 S, MT).
When is the first and last frost in Lake Mary Ronan?
In half of years the last spring frost (32°) comes by May 1 and the first fall frost by October 15, about 165 frost-free days, at Bigfork 13 S, MT.
What growing zone is Lake Mary Ronan in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −12°.
What is the best time of year to visit Lake Mary Ronan?
By one simple rule (highs of 62–84° and lows of 40° or more), June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Lake Mary Ronan getting warmer?
Yes: 1991–2020 averaged 1.2° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 60% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Lake Mary Ronan.
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.