Ashton, Idaho climate: Normal weather by month, frost dates and records
Ashton's normal year runs from 13°F January nights to 83°F July afternoons, with 19.7 inches of precipitation and 70 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.3°C, January lows of −10°C, July highs of 28°C, 500 mm of precipitation a year.
- NOAA stationAshton (1 mi N)
- Station IDUSC00100470
- Location44.07°N 111.46°W
- Elevation5,212 ft (1,589 m)
- Population982
On October 23, the normal high in Ashton is 53°F and the normal low 30°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 Ashton.
- Jan 29° 13°
- Feb 33° 17°
- Mar 42° 25°
- Apr 54° 31°
- May 65° 40°
- Jun 73° 46°
- Jul 83° 51°
- Aug 83° 49°
- Sep 73° 42°
- Oct 57° 32°
- Nov 40° 23°
- Dec 29° 15°
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 Ashton each month?
July is the warmest month, with normal highs of 83°F; January the coldest, with normal lows of 13°F. The most precipitation falls in January (2.31 in), the least in July (0.64 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 29°F | 13°F | 21.1°F | 2.31 | 19.8 | 9 | <1 | 31 | 9 h 10 min |
| February | 33°F | 17°F | 24.7°F | 1.53 | 10.7 | 7 | <1 | 27 | 10 h 30 min |
| March | 42°F | 25°F | 33.4°F | 1.29 | 5.3 | 7 | <1 | 27 | 11 h 50 min |
| April | 54°F | 31°F | 42.6°F | 1.70 | 2.0 | 7 | <1 | 19 | 13 h 20 min |
| May | 65°F | 40°F | 52.5°F | 2.24 | 0.0 | 8 | <1 | 6 | 14 h 40 min |
| June | 73°F | 46°F | 59.4°F | 2.15 | 0.0 | 6 | <1 | 1 | 15 h 30 min |
| July | 83°F | 51°F | 66.7°F | 0.64 | 0.0 | 3 | 5 | <1 | 15 h 10 min |
| August | 83°F | 49°F | 65.6°F | 0.85 | 0.0 | 4 | 4 | <1 | 14 h |
| September | 73°F | 42°F | 57.1°F | 1.17 | 0.0 | 5 | <1 | 3 | 12 h 40 min |
| October | 57°F | 32°F | 44.6°F | 1.63 | 1.6 | 5 | <1 | 18 | 11 h 10 min |
| November | 40°F | 23°F | 31.4°F | 1.90 | 10.5 | 7 | <1 | 26 | 9 h 40 min |
| December | 29°F | 15°F | 21.9°F | 2.26 | 20.2 | 10 | <1 | 30 | 8 h 50 min |
| Year (annual) | 55°F | 32°F | 43.4°F | 19.67 | 70.1 | 78 | 9 | 190 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −2°C | −10°C | −6.1°C | 59 mm | 50 cm |
| February | 0°C | −8°C | −4.1°C | 39 mm | 27 cm |
| March | 6°C | −4°C | 0.8°C | 33 mm | 13 cm |
| April | 12°C | 0°C | 5.9°C | 43 mm | 5 cm |
| May | 19°C | 4°C | 11.4°C | 57 mm | 0 cm |
| June | 23°C | 8°C | 15.2°C | 55 mm | 0 cm |
| July | 28°C | 11°C | 19.3°C | 16 mm | 0 cm |
| August | 28°C | 9°C | 18.7°C | 22 mm | 0 cm |
| September | 23°C | 5°C | 13.9°C | 30 mm | 0 cm |
| October | 14°C | 0°C | 7.0°C | 41 mm | 4 cm |
| November | 5°C | −5°C | −0.3°C | 48 mm | 27 cm |
| December | −2°C | −10°C | −5.6°C | 57 mm | 51 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00100470; 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 Ashton?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, July has the fewest days with rain (3).
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 USC00100470.
When is the last frost in Ashton?
In Ashton, the last spring frost (32°F) comes after May 21 in half of years and after June 13 in one year in ten; the first autumn frost comes before September 21 in half of years and before September 4 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 211 year in 10 after June 13; 9 in 10 after May 4
- First autumn frost, half of years before
- September 211 year in 10 before September 4; 9 in 10 before October 7
NOAA puts the median frost-free season at 121 days, and the season without a hard freeze (28°F) at 152 days.
A hard freeze (28°F) comes after May 3 in half of springs and before October 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Ashton in zone 5a in ZIP code 83420, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Ashton's NOAA station is in zone 5b: the coldest night of a typical year reaches −13°F (15 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Idaho · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00100470; 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 Ashton?
In a normal year in Ashton, 9 days a year reach 90°F, 190 nights fall to 32°F or colder and 78 days bring measurable precipitation.
- Days at 90°F or more
- 9a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 190a normal year
- Days that stay below freezing
- 64high of 32°F or less
- Days with 0.01 inch of precipitation
- 78a normal year
- Days with 1 inch of snow or more
- 25a normal year
The highest temperature in this station's record (since 1897) is 101°F, on July 23, 2007; the lowest is −37°F, on February 7, 1933.
The wettest calendar year on that record is 1983, with 30.09 in; the snowiest season is 1951–52, with 161.6 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00100470; records: ACIS (NOAA Regional Climate Centers), station USC00100470. Records use complete months only; a month missing more than three days is left out.
How sunny is Ashton?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Ashton, 4.2 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (56%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 60% | 1.6 |
| February | 65% | 2.6 |
| March | 65% | 3.7 |
| April | 68% | 5.0 |
| May | 70% | 5.9 |
| June | 77% | 6.9 |
| July | 87% | 7.5 |
| August | 86% | 6.3 |
| September | 81% | 4.8 |
| October | 71% | 3.0 |
| November | 62% | 1.8 |
| December | 56% | 1.3 |
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 Ashton need?
A normal year in Ashton brings 8,043 heating degree days, 50% more than the median U.S. place (5,373), and 210 cooling degree days, 77% 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 1,730 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,359 | 0 |
| February | 1,128 | 0 |
| March | 980 | 0 |
| April | 672 | 0 |
| May | 390 | 3 |
| June | 189 | 21 |
| July | 45 | 99 |
| August | 57 | 76 |
| September | 246 | 11 |
| October | 631 | 0 |
| November | 1,008 | 0 |
| December | 1,336 | 0 |
| Year (annual) | 8,043 | 210 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00100470. 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 Ashton been warmer than normal lately?
2023 averaged 42.4°F, 1.0°F below the 1991-2020 normal of 43.4°F. 1 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 44.0°F | +0.6°F | 15.24 | – |
| 2022 | 41.5°F | −1.9°F | 19.63 | – |
| 2023 | 42.4°F | −1.0°F | 21.94 | – |
Over 82 complete years from 1903 to 2023, the station's annual mean temperature rose at a fitted 1.4°F per century (+0.08°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00100470; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Ashton's climate compare?
Ashton is warmer than 17 of the other 84 places with their own NOAA record in Idaho, and wetter than 53. Across the 7,247 U.S. stations with normals, its annual mean of 43.4°F is warmer than 13%.
In the Köppen classification computed from these normals, Ashton is Dsb: continental, dry-summer, warm summer. 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 Ashton share this climate record?
2 places have no NOAA station with 1991-2020 normals of their 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.
- Drummond, ID15 people · 7 mi SE
- Warm River, ID1 people · 8 mi NE
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 Ashton's climate
What is the coldest month in Ashton?
January, with a normal high of 29°F and a normal low of 13°F. The warmest is July (83°F by day, 51°F at night).
Does it snow in Ashton?
Yes: 70 inches in a normal year, falling on 31 days with 0.1 inch or more, the most in December (20.2 inches).
What is the rainiest month in Ashton?
January, with 2.31 in of precipitation in a normal year; the driest is July with 0.64 in.
What plant hardiness zone is Ashton in?
The USDA's 2023 map puts Ashton in zone 5a in ZIP code 83420, the nearest ZIP area. By the same method at Ashton's NOAA station, the coldest night of a typical year reaches −13°F (15 years, 1991-2020): zone 5b.
How late can frost come in Ashton?
In half of years the last 32°F night comes after May 21; in one year in ten it comes after June 13. Waiting until June 13 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Idaho climateThe statewide normals and every place in the state
- St. Anthony, ID14 miles from this station, 43.1°F a year
- Tetonia, ID17 miles from this station, 39.4°F a year
- Sugar City, ID19 miles from this station, 42.7°F a year
- Rexburg, ID24 miles from this station, 44.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made