January in Alpine Northwest bites harder than in 94% of U.S. towns
Midsummer highs settle at about 83°. The wettest month is May; the driest is July. By precipitation alone, it ranks drier than 92% of U.S. towns. Comfortable outdoor weather lasts from June to August, with highs of 73–83°.
A year in Alpine Northwest at a glance
Each month’s typical high and low, and what it brings.
What stands out about Alpine Northwest’s climate
Compared with towns across the U.S., with Alpine Northwest’s place in Wyoming beside it.
What a year in Alpine Northwest feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
A freeze is possible in every month
About 198 nights a year fall to 32° or below, and 16 to 0° or below. Frost and day counts come from NOAA’s station at Swan Valley, ID, 21 miles from the town’s center, 240 ft lower.
The 2023 USDA map puts Alpine Northwest’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −19°. 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 16 inches of rain a year
May is the wettest month and July the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Alpine Northwest
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 Valley, ID.
Living with Alpine Northwest’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 5a, and frost can come in any month. The longest frost-free stretch in half of years is about 69 days.
Months with highs of 62–84° and lows of 40° or more: June, July and August.
Parks & trails →Of the yearly building losses FEMA expects in Alpine Northwest from natural hazards, avalanches are the largest share (81%); heat waves, cold waves, winter storms and ice storms together are 1%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Alpine Northwest and similar climates
TownRatings has no climate map of the towns around Alpine Northwest 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 Alpine Northwest averaged 1.3° warmer than the 1900s. The biggest change is in March (+3.3°).
A smaller shift than in 55% 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 Alpine Northwest compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Alpine Northwest’s place among Wyoming’s.
Alpine Northwest weather by month
Highs, lows and precipitation from NOAA’s grid at Alpine Northwest’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 29° | 9° | 1.5" | 13° – 25° |
| February | 33° | 11° | 1.2" | 18° – 29° |
| March | 43° | 20° | 1.2" | 26° – 37° |
| April | 53° | 27° | 1.3" | 34° – 45° |
| May | 64° | 35° | 1.9" | 43° – 54° |
| June | 73° | 41° | 1.5" | 52° – 63° |
| July | 83° | 46° | 0.8" | 55° – 70° |
| August | 82° | 45° | 1.1" | 58° – 66° |
| September | 72° | 37° | 1.3" | 51° – 58° |
| October | 58° | 28° | 1.4" | 34° – 49° |
| November | 41° | 19° | 1.4" | 22° – 38° |
| December | 29° | 10° | 1.6" | 15° – 25° |
| Year | 55° | 27° | 16.1" |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 22° to 38°. September is the most reliable, staying within 8°.
Where Alpine Northwest’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 Alpine Northwest’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Swan Valley, ID, 21 miles from the town’s center, 240 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 Alpine Northwest’s climate
What is the weather like in Alpine Northwest?
A typical July afternoon reaches 83°, a January night drops to 9°. Colder January nights than 94% of U.S. towns; cooler July afternoons than 74% of U.S. towns.
How cold does it get in Alpine Northwest in winter?
January nights average 9°. About 198 nights a year reach 32° or below and 16 reach 0° or below. In the coldest January of the last 30 years the month averaged 13°.
How hot does it get in Alpine Northwest?
July, with a typical high of 83° and a low of 46°. About 14 days a year reach 90° (Swan Valley, ID).
When is the first and last frost in Alpine Northwest?
There is no reliable frost-free season: at Swan Valley, ID, every month has nights at 32° or below, about 198 a year. In half of years the longest stretch without a freeze is about 69 days.
What growing zone is Alpine Northwest in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −19°.
What is the best time of year to visit Alpine Northwest?
By one simple rule (highs of 62–84° and lows of 40° or more), June, July and August. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Alpine Northwest getting warmer?
Yes: 1991–2020 averaged 1.3° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 55% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Alpine Northwest.
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.