Challis, Idaho climate: Normal weather by month, frost dates and records
Challis's normal year runs from 11°F December nights to 87°F July afternoons, with 6.9 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.9°C, December lows of −12°C, July highs of 31°C, 176 mm of precipitation a year.
- NOAA stationChallis Airport
- Station IDUSW00004114
- Location44.52°N 114.22°W
- Elevation5,033 ft (1,534 m)
- Population944
On October 22, the normal high in Challis is 55°F and the normal low 29°F, and the chance of measurable rain or snow is 17%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Challis.
- Jan 29° 11°
- Feb 37° 17°
- Mar 49° 26°
- Apr 57° 31°
- May 67° 40°
- Jun 76° 46°
- Jul 87° 52°
- Aug 85° 50°
- Sep 75° 42°
- Oct 59° 32°
- Nov 41° 21°
- Dec 29° 11°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Challis each month?
July is the warmest month, with normal highs of 87°F; December the coldest, with normal lows of 11°F. The most precipitation falls in May (0.93 in), the least in February (0.36 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 29°F | 11°F | 20.0°F | 0.41 | 6 | <1 | 31 | 9 h 10 min |
| February | 37°F | 17°F | 26.8°F | 0.36 | 5 | <1 | 28 | 10 h 30 min |
| March | 49°F | 26°F | 37.3°F | 0.46 | 7 | <1 | 28 | 11 h 50 min |
| April | 57°F | 31°F | 44.0°F | 0.52 | 7 | <1 | 19 | 13 h 30 min |
| May | 67°F | 40°F | 53.4°F | 0.93 | 9 | <1 | 6 | 14 h 50 min |
| June | 76°F | 46°F | 60.9°F | 0.93 | 8 | 3 | 1 | 15 h 30 min |
| July | 87°F | 52°F | 69.3°F | 0.42 | 5 | 15 | <1 | 15 h 10 min |
| August | 85°F | 50°F | 67.4°F | 0.45 | 5 | 9 | <1 | 14 h 10 min |
| September | 75°F | 42°F | 58.2°F | 0.85 | 5 | 1 | 3 | 12 h 40 min |
| October | 59°F | 32°F | 45.0°F | 0.56 | 5 | <1 | 19 | 11 h |
| November | 41°F | 21°F | 30.5°F | 0.52 | 6 | <1 | 28 | 9 h 40 min |
| December | 29°F | 11°F | 19.8°F | 0.52 | 7 | <1 | 31 | 8 h 50 min |
| Year (annual) | 57°F | 31°F | 44.4°F | 6.93 | 75 | 28 | 193 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −2°C | −12°C | −6.7°C | 10 mm |
| February | 3°C | −8°C | −2.9°C | 9 mm |
| March | 10°C | −4°C | 2.9°C | 12 mm |
| April | 14°C | 0°C | 6.7°C | 13 mm |
| May | 19°C | 4°C | 11.9°C | 24 mm |
| June | 24°C | 8°C | 16.1°C | 24 mm |
| July | 31°C | 11°C | 20.7°C | 11 mm |
| August | 29°C | 10°C | 19.7°C | 11 mm |
| September | 24°C | 6°C | 14.6°C | 22 mm |
| October | 15°C | 0°C | 7.2°C | 14 mm |
| November | 5°C | −6°C | −0.8°C | 13 mm |
| December | −2°C | −12°C | −6.8°C | 13 mm |
NOAA publishes no 1991-2020 snowfall normal for this station, and no record within 25 miles keeps one, so snow is left out here rather than estimated.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00004114; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Challis?
Normal highs sit between 65°F and 85°F in May, June, August and September. Of those, September has the fewest days with rain (5).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00004114.
When is the last frost in Challis?
In Challis, the last spring frost (32°F) comes after May 14 in half of years and after June 2 in one year in ten; the first autumn frost comes before September 25 in half of years and before September 10 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 141 year in 10 after June 2; 9 in 10 after May 2
- First autumn frost, half of years before
- September 251 year in 10 before September 10; 9 in 10 before October 7
NOAA puts the median frost-free season at 131 days, and the season without a hard freeze (28°F) at 158 days.
A hard freeze (28°F) comes after May 1 in half of springs and before October 7 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Challis in zone 5b in ZIP code 83235, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Challis's NOAA station is in zone 5b: the coldest night of a typical year reaches −15°F (22 complete years).
Frost dates for every NOAA station in Idaho · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00004114; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Challis?
In a normal year in Challis, 28 days a year reach 90°F (1 of them 100°F or more), 193 nights fall to 32°F or colder and 75 days bring measurable precipitation.
- Days at 90°F or more
- 28a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 193a normal year
- Days that stay below freezing
- 54high of 32°F or less
- Days with 0.01 inch of precipitation
- 75a normal year
The highest temperature in Challis's official record (kept by the National Weather Service since 1895) is 103°F, on July 26, 1964; the lowest is −34°F, on December 23, 1983.
The wettest calendar year on that record is 2010, with 10.79 in; the snowiest season is 1916–17, with 26.3 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00004114; records: ACIS (NOAA Regional Climate Centers), NWS threaded record LLJthr. Records use complete months only; a month missing more than three days is left out.
How sunny is Challis?
Over a year 77% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Challis, 4.4 kWh per square metre a day. July is the sunniest month (85%) and December the cloudiest (65%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 72% | 1.9 |
| February | 74% | 2.9 |
| March | 73% | 4.1 |
| April | 72% | 5.3 |
| May | 72% | 6.1 |
| June | 77% | 7.0 |
| July | 85% | 7.4 |
| August | 84% | 6.3 |
| September | 82% | 4.9 |
| October | 75% | 3.2 |
| November | 68% | 1.9 |
| December | 65% | 1.5 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Challis need?
A normal year in Challis brings 7,795 heating degree days, 45% more than the median U.S. place (5,373), and 312 cooling degree days, 66% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,959 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,397 | 0 |
| February | 1,068 | 0 |
| March | 857 | 0 |
| April | 630 | 0 |
| May | 363 | 4 |
| June | 155 | 32 |
| July | 19 | 152 |
| August | 36 | 110 |
| September | 217 | 15 |
| October | 618 | 0 |
| November | 1,034 | 0 |
| December | 1,401 | 0 |
| Year (annual) | 7,795 | 312 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00004114. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Challis been warmer than normal lately?
2025 averaged 46.8°F, 2.4°F above the 1991-2020 normal of 44.4°F. 2 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 46.7°F | +2.3°F | 4.95 |
| 2023 | 43.0°F | −1.4°F | 8.87 |
| 2025 | 46.8°F | +2.4°F | 7.96 |
Source: observed years: ACIS, station USW00004114. A year counts only with all twelve months complete.
How does Challis's climate compare?
Challis is warmer than 26 of the other 84 places with their own NOAA record in Idaho, and wetter than 1. Across the 7,247 U.S. stations with normals, its annual mean of 44.4°F is warmer than 17%.
In the Köppen classification computed from these normals, Challis is BSk: cold semi-arid steppe. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Challis share this climate record?
Clayton has no NOAA station with 1991-2020 normals of its own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Clayton, ID12 people · 20 mi SW
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Challis's climate
What is the coldest month in Challis?
December, with a normal high of 29°F and a normal low of 11°F. The warmest is July (87°F by day, 52°F at night).
What is the rainiest month in Challis?
May, with 0.93 in of precipitation in a normal year; the driest is February with 0.36 in.
What plant hardiness zone is Challis in?
The USDA's 2023 map puts Challis in zone 5b in ZIP code 83235, the nearest ZIP area. By the same method at Challis's NOAA station, the coldest night of a typical year reaches −15°F (22 years, 1991-2020): zone 5b.
How late can frost come in Challis?
In half of years the last 32°F night comes after May 14; in one year in ten it comes after June 2. Waiting until June 2 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Idaho climateThe statewide normals and every place in the state
- May (2 mi SSE), ID16 miles from this station, 42.4°F a year
- Middle Fork Lodge, ID42 miles from this station, 45.1°F a year
- Chilly Barton Flat, ID42 miles from this station, 41.0°F a year
- Stanley, ID43 miles from this station, 37.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made