Johnny Sack Cabin · Photo: Pilleyk · CC BY-SA 3.0Island Park gets about 177 inches of snow a winter, more than all but 34 U.S. towns
High summer brings afternoon highs near 78°. By July afternoons alone, it runs cooler than 96% of U.S. towns. Decade by decade the climate has edged up, 1.4° above 1901–2000. Radiators earn their keep from October to May, the months that average under 50°.
A year in Island Park at a glance
Each month’s typical high and low, and what it brings.
What stands out about Island Park’s climate
Compared with towns across the U.S., with Island Park’s place in Idaho beside it.
What a year in Island Park 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 247 nights a year fall to 32° or below, and 38 to 0° or below. Frost and day counts come from NOAA’s station at Island Park, ID, 8 miles from the town’s center, at about the same height.
The 2023 USDA map puts Island Park’s center in zone 3b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −31°. 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 177 inches of snow a winter
Snow, measured at Hebgen Dam, MT, falls mostly in January and December. Precipitation (rain plus melted snow) adds up to 28 inches a year; December is the wettest month and August the driest. Rain or snow falls on about 118 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Island Park
Nearly all of the work is heating: a normal year has almost no cooling days. Months averaging under 55° run from September through June.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Island Park, ID.
Living with Island Park’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 3b, and frost can come in any month. The longest frost-free stretch in half of years is about 49 days.
Months with highs of 62–84° and lows of 40° or more: July and August. 5.8 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Island Park from natural hazards, river flooding is the largest share (43%); heat waves, cold waves, winter storms and ice storms together are 3%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Island Park and similar climates
TownRatings has no climate map of the towns around Island Park yet.
Climates most like Island Park’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 |
|---|---|---|---|---|
| Island Park, ID | 6° | 78° | 28" | 177" |
| Ishpeming, MI | 5° | 77° | 33" | 197" |
| Aspen, CO | 10° | 80° | 20" | 171" |
| Lyndon, VT | 5° | 79° | 41" | 142" |
| Summit Park, UT | 19° | 79° | 30" | 153" |
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 Island Park averaged 1.4° warmer than the 1900s. The biggest change is in March (+3.6°).
A bigger shift than in 50% 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 Island Park compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Island Park’s place among Idaho’s.
Island Park weather by month
Highs, lows and precipitation from NOAA’s grid at Island Park’s center; snow, wet days and snow on the ground from Hebgen Dam, MT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 26° | 6° | 3.1" | 43.8" | 14 | 31 | 10° – 22° |
| February | 31° | 7° | 2.6" | 33.7" | 11 | 29 | 14° – 25° |
| March | 40° | 16° | 2.6" | 20.6" | 9 | 30 | 22° – 33° |
| April | 48° | 24° | 2.5" | 7.7" | 10 | 19 | 30° – 41° |
| May | 59° | 32° | 2.9" | 1.2" | 12 | 2 | 40° – 50° |
| June | 68° | 38° | 2.5" | 0.0" | 12 | 0 | 47° – 60° |
| July | 78° | 43° | 1.2" | 0.0" | 8 | 0 | 51° – 67° |
| August | 77° | 41° | 1.2" | 0.0" | 6 | 0 | 54° – 63° |
| September | 67° | 34° | 1.5" | 0.0" | 6 | 0 | 47° – 55° |
| October | 51° | 25° | 2.0" | 4.1" | 8 | 2 | 29° – 45° |
| November | 36° | 15° | 2.6" | 20.9" | 10 | 20 | 17° – 34° |
| December | 26° | 6° | 3.6" | 45.2" | 13 | 31 | 12° – 22° |
| Year | 50° | 24° | 28.3" | 177.2" | 118 | 162 |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 17° to 34°. September is the most reliable, staying within 8°.
Where Island Park’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 Island Park’s center.
- Snow: Hebgen Dam, MT.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Island Park, ID, 8 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 Island Park’s climate
What is the weather like in Island Park?
A typical July afternoon reaches 78°, a January night drops to 6°, and about 177 inches of snow falls in a normal winter. Colder January nights than 98% of U.S. towns; cooler July afternoons than 96% of U.S. towns.
How cold does it get in Island Park in winter?
January nights average 6°. About 247 nights a year reach 32° or below and 38 reach 0° or below. In the coldest January of the last 30 years the month averaged 10°.
How much snow does Island Park get?
About 177 inches in a normal winter at Hebgen Dam, MT, most of it in January and December, with snow on the ground about 162 days a year.
How hot does it get in Island Park?
July, with a typical high of 78° and a low of 43°. About 3 days a year reach 90° (Island Park, ID).
When is the first and last frost in Island Park?
There is no reliable frost-free season: at Island Park, ID, every month has nights at 32° or below, about 247 a year. In half of years the longest stretch without a freeze is about 49 days.
What growing zone is Island Park in?
Zone 3b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −31°.
What is the best time of year to visit Island Park?
By one simple rule (highs of 62–84° and lows of 40° or more), July and August. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Island Park getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 50% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Island Park.
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.