Chilly Barton Flat, Idaho climate: Climate normals at a NOAA weather station
Chilly Barton Flat's normal year runs from 7°F January nights to 82°F July afternoons, with 8.0 inches of precipitation and 18 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 5.0°C, January lows of −14°C, July highs of 28°C, 202 mm of precipitation a year.
- NOAA stationChilly Barton Flat
- Station IDUSC00101671
- Location43.98°N 113.83°W
- Elevation6,260 ft (1,908 m)
On October 22, the normal high in Chilly Barton Flat is 54°F and the normal low 26°F, and the chance of measurable rain or snow is 16%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Chilly Barton Flat.
- Jan 31° 7°
- Feb 34° 11°
- Mar 44° 21°
- Apr 53° 28°
- May 63° 35°
- Jun 72° 41°
- Jul 82° 47°
- Aug 80° 45°
- Sep 72° 37°
- Oct 57° 28°
- Nov 41° 18°
- Dec 30° 9°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Chilly Barton Flat each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 7°F. The most precipitation falls in June (1.48 in), the least in February (0.23 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 31°F | 7°F | 19.0°F | 0.28 | 4.6 | 4 | <1 | 31 | 9 h 10 min |
| February | 34°F | 11°F | 22.4°F | 0.23 | 2.7 | 4 | <1 | 28 | 10 h 30 min |
| March | 44°F | 21°F | 32.3°F | 0.46 | 1.9 | 4 | <1 | 29 | 11 h 50 min |
| April | 53°F | 28°F | 40.3°F | 0.74 | 1.3 | 7 | <1 | 24 | 13 h 20 min |
| May | 63°F | 35°F | 48.7°F | 1.20 | 0.4 | 9 | <1 | 12 | 14 h 40 min |
| June | 72°F | 41°F | 56.5°F | 1.48 | 0.2 | 8 | <1 | 3 | 15 h 30 min |
| July | 82°F | 47°F | 64.5°F | 0.58 | 0.0 | 5 | 3 | <1 | 15 h 10 min |
| August | 80°F | 45°F | 62.6°F | 0.66 | 0.0 | 6 | 2 | 1 | 14 h |
| September | 72°F | 37°F | 54.3°F | 0.65 | 0.2 | 5 | <1 | 8 | 12 h 40 min |
| October | 57°F | 28°F | 42.8°F | 0.80 | 0.9 | 5 | <1 | 23 | 11 h 10 min |
| November | 41°F | 18°F | 29.3°F | 0.44 | 1.6 | 5 | <1 | 28 | 9 h 40 min |
| December | 30°F | 9°F | 19.2°F | 0.44 | 4.5 | 5 | <1 | 31 | 9 h |
| Year (annual) | 55°F | 27°F | 41.0°F | 7.96 | 18.3 | 67 | 5 | 217 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −14°C | −7.2°C | 7 mm | 12 cm |
| February | 1°C | −12°C | −5.3°C | 6 mm | 7 cm |
| March | 6°C | −6°C | 0.2°C | 12 mm | 5 cm |
| April | 12°C | −2°C | 4.6°C | 19 mm | 3 cm |
| May | 17°C | 2°C | 9.3°C | 30 mm | 1 cm |
| June | 22°C | 5°C | 13.6°C | 38 mm | 1 cm |
| July | 28°C | 8°C | 18.1°C | 15 mm | 0 cm |
| August | 27°C | 7°C | 17.0°C | 17 mm | 0 cm |
| September | 22°C | 3°C | 12.4°C | 17 mm | 1 cm |
| October | 14°C | −2°C | 6.0°C | 20 mm | 2 cm |
| November | 5°C | −8°C | −1.5°C | 11 mm | 4 cm |
| December | −1°C | −13°C | −7.1°C | 11 mm | 11 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00101671; 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.
Which months are mildest at Chilly Barton Flat?
Normal highs sit between 65°F and 85°F in June, July, 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 USC00101671.
When is the last frost at Chilly Barton Flat?
In Chilly Barton Flat, the last spring frost (32°F) comes after June 14 in half of years and after June 30 in one year in ten; the first autumn frost comes before September 8 in half of years and before August 26 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
- June 141 year in 10 after June 30; 9 in 10 after May 27
- First autumn frost, half of years before
- September 81 year in 10 before August 26; 9 in 10 before September 22
NOAA puts the median frost-free season at 86 days, and the season without a hard freeze (28°F) at 118 days.
A hard freeze (28°F) comes after May 24 in half of springs and before September 20 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Chilly Barton Flat in zone 5a in ZIP code 83251, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 5a: the coldest night of a typical year reaches −17°F (23 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 USC00101671; 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 at Chilly Barton Flat?
In a normal year in Chilly Barton Flat, 5 days a year reach 90°F, 217 nights fall to 32°F or colder and 67 days bring measurable precipitation.
- Days at 90°F or more
- 5a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 217a normal year
- Days that stay below freezing
- 59high of 32°F or less
- Days with 0.01 inch of precipitation
- 67a normal year
- Days with 1 inch of snow or more
- 10a normal year
The highest temperature in this station's record (since 1948) is 100°F, on August 25, 2008; the lowest is −42°F, on January 25, 1949.
The wettest calendar year on that record is 1951, with 13.02 in; the snowiest season is 1951–52, with 64.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00101671; records: ACIS (NOAA Regional Climate Centers), station USC00101671. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Chilly Barton Flat?
Over a year 79% of the sunlight that would reach the ground under clear skies gets through the clouds at Chilly Barton Flat, 4.5 kWh per square metre a day. July is the sunniest month (89%) and December the cloudiest (64%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 68% | 1.9 |
| February | 70% | 2.8 |
| March | 71% | 4.0 |
| April | 73% | 5.4 |
| May | 77% | 6.5 |
| June | 83% | 7.5 |
| July | 89% | 7.6 |
| August | 88% | 6.5 |
| September | 86% | 5.2 |
| October | 81% | 3.5 |
| November | 73% | 2.2 |
| December | 64% | 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 many heating and cooling degree days does Chilly Barton Flat record?
A normal year at Chilly Barton Flat brings 8,818 heating degree days, 64% more than the median U.S. place (5,373), and 92 cooling degree days, 90% fewer than the median (908). Nine months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,327 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,428 | 0 |
| February | 1,191 | 0 |
| March | 1,015 | 0 |
| April | 740 | 0 |
| May | 507 | 0 |
| June | 262 | 8 |
| July | 69 | 53 |
| August | 104 | 28 |
| September | 322 | 2 |
| October | 690 | 0 |
| November | 1,071 | 0 |
| December | 1,420 | 0 |
| Year (annual) | 8,818 | 92 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00101671. 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.
Have recent years at Chilly Barton Flat been warmer than normal?
2025 averaged 44.2°F, 3.2°F above the 1991-2020 normal of 41.0°F. 2 of the 2 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 42.7°F | +1.7°F | 8.21 | 30.4 |
| 2025 | 44.2°F | +3.2°F | 10.29 | 23.8 |
Over 38 complete years from 1951 to 2025, the station's annual mean temperature rose at a fitted 2.8°F per century (+0.16°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00101671; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Chilly Barton Flat's climate compare?
Chilly Barton Flat is warmer than 6 of the 85 places with their own NOAA record in Idaho, and wetter than 3. Across the 7,247 U.S. stations with normals, its annual mean of 41.0°F is warmer than 7%.
In the Köppen classification computed from these normals, Chilly Barton Flat 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.
Questions about Chilly Barton Flat's climate
What is the coldest month at Chilly Barton Flat?
January, with a normal high of 31°F and a normal low of 7°F. The warmest is July (82°F by day, 47°F at night).
Does it snow at Chilly Barton Flat?
Yes: 18 inches in a normal year, falling on 16 days with 0.1 inch or more, the most in January (4.6 inches).
What is the rainiest month at Chilly Barton Flat?
June, with 1.48 in of precipitation in a normal year; the driest is February with 0.23 in.
What plant hardiness zone is Chilly Barton Flat in?
The USDA's 2023 map puts Chilly Barton Flat in zone 5a in ZIP code 83251, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −17°F (23 years, 1991-2020): zone 5a.
How late can frost come at Chilly Barton Flat?
In half of years the last 32°F night comes after June 14; in one year in ten it comes after June 30. Waiting until June 30 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Idaho climateThe statewide normals and every place in the state
- Mackay, ID11 miles from this station, 42.2°F a year
- Ketchum, ID34 miles from this station, 40.2°F a year
- Arco, ID35 miles from this station, 43.7°F a year
- Craters Of The Moon, ID38 miles from this station, 39.1°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made