Summer arrives softly in Swan Lake, cooler than in 95% of U.S. towns
Deep winter brings January lows near 20°. The wettest month is June; the driest is August. By precipitation alone, it ranks drier than 85% of U.S. towns. Picnics, hikes and garden evenings come into their own from June to September, with highs of 67–79°.
A year in Swan Lake at a glance
Each month’s typical high and low, and what it brings.
What stands out about Swan Lake’s climate
Compared with towns across the U.S., with Swan Lake’s place in Montana beside it.
What a year in Swan Lake feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 121 frost-free days a year
In half of years the last 32° night comes by May 17 and the first by September 19. Frost dates and degree days from Swan Lake, MT, 2.3 miles away.
The 2023 USDA map puts Swan Lake’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 51 inches of snow a winter
Snow, measured at Creston, MT, falls mostly in January and December. Precipitation (rain plus melted snow) adds up to 31 inches a year; June is the wettest month and August the driest. Rain or snow falls on about 129 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Swan Lake
98% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from September 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 Swan Lake, MT.
Living with Swan Lake’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
121 frost-free days in zone 5b. 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 19.
Months with highs of 62–84° and lows of 40° or more: June, July, August and September. 7.1 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Swan Lake from natural hazards, avalanches are the largest share (50%); heat waves, cold waves, winter storms and ice storms together are 7%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Swan Lake and similar climates
TownRatings has no climate map of the towns around Swan Lake yet.
Climates most like Swan Lake’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 |
|---|---|---|---|---|
| Swan Lake, MT | 20° | 79° | 31" | 51" |
| Porter, NY | 21° | 79° | 33" | 55" |
| St. Francis, WI | 16° | 80° | 34" | 49" |
| Alpena, MI | 14° | 78° | 31" | 59" |
| Winthrop Harbor, IL | 17° | 81° | 36" | 36" |
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 Swan Lake averaged 1.6° warmer than the 1900s. The biggest change is in January (+4.4°).
A bigger shift than in 68% 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 Swan Lake compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Swan Lake’s place among Montana’s.
Swan Lake weather by month
Highs, lows and precipitation from NOAA’s grid at Swan Lake’s center; snow, wet days and snow on the ground from Creston, MT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 31° | 20° | 3.2" | 13.8" | 14 | 24 | 16° – 32° |
| February | 35° | 20° | 2.3" | 11.0" | 10 | 19 | 15° – 36° |
| March | 43° | 25° | 2.6" | 6.3" | 11 | 11 | 26° – 41° |
| April | 51° | 31° | 2.7" | 2.1" | 11 | 1 | 36° – 48° |
| May | 61° | 38° | 2.9" | 0.1" | 13 | 0 | 44° – 55° |
| June | 68° | 45° | 3.9" | 0.0" | 14 | 0 | 53° – 64° |
| July | 79° | 50° | 1.2" | 0.0" | 8 | 0 | 54° – 71° |
| August | 78° | 49° | 1.2" | 0.0" | 6 | 0 | 58° – 67° |
| September | 67° | 41° | 1.9" | 0.0" | 8 | 0 | 50° – 60° |
| October | 52° | 33° | 2.8" | 0.5" | 11 | 0 | 36° – 48° |
| November | 38° | 27° | 3.2" | 3.4" | 12 | 5 | 25° – 40° |
| December | 30° | 20° | 3.2" | 13.4" | 13 | 18 | 19° – 31° |
| Year | 53° | 33° | 31.2" | 50.6" | 129 | 79 |
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 36°. August is the most reliable, staying within 9°.
Where Swan Lake’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 Swan Lake’s center.
- Snow: Creston, MT.
- Frost dates, heating and cooling: Swan Lake, MT, 2.3 miles away.
- 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 Swan Lake’s climate
What is the weather like in Swan Lake?
A typical July afternoon reaches 79°, a January night drops to 20°, and about 51 inches of snow falls in a normal winter. Colder January nights than 60% of U.S. towns; cooler July afternoons than 95% of U.S. towns.
How cold does it get in Swan Lake in winter?
January nights average 20°. About 204 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 16°.
How much snow does Swan Lake get?
About 51 inches in a normal winter at Creston, MT, most of it in January and December, with snow on the ground about 79 days a year.
How hot does it get in Swan Lake?
July, with a typical high of 79° and a low of 50°. About 16 days a year reach 90° (Swan Lake, MT).
When is the first and last frost in Swan Lake?
In half of years the last spring frost (32°) comes by May 17 and the first fall frost by September 19, about 121 frost-free days, at Swan Lake, MT.
What growing zone is Swan Lake 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 Swan Lake?
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 Swan Lake getting warmer?
Yes: 1991–2020 averaged 1.6° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 68% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Swan Lake.
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.