Winchester, Idaho climate: Normal weather by month, frost dates and records
Winchester's normal year runs from 22°F December nights to 79°F August afternoons, with 21.8 inches of precipitation and 87 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.0°C, December lows of −5°C, August highs of 26°C, 553 mm of precipitation a year.
- NOAA stationWinchester
- Station IDUSC00109846
- Location46.24°N 116.62°W
- Elevation3,972 ft (1,211 m)
- Population366
On October 22, the normal high in Winchester is 53°F and the normal low 33°F, and the chance of measurable rain or snow is 37%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Winchester.
- Jan 37° 23°
- Feb 39° 23°
- Mar 45° 27°
- Apr 52° 32°
- May 60° 39°
- Jun 67° 43°
- Jul 78° 49°
- Aug 79° 49°
- Sep 70° 42°
- Oct 56° 35°
- Nov 43° 28°
- Dec 35° 22°
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 Winchester each month?
August is the warmest month, with normal highs of 79°F; December the coldest, with normal lows of 22°F. The most precipitation falls in May (2.76 in), the least in August (0.71 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 37°F | 23°F | 29.7°F | 1.75 | 17.9 | 15 | <1 | 27 | 9 h |
| February | 39°F | 23°F | 31.2°F | 1.55 | 13.1 | 13 | <1 | 26 | 10 h 20 min |
| March | 45°F | 27°F | 36.1°F | 2.33 | 15.8 | 16 | <1 | 26 | 11 h 50 min |
| April | 52°F | 32°F | 41.7°F | 2.68 | 9.1 | 16 | <1 | 19 | 13 h 30 min |
| May | 60°F | 39°F | 49.2°F | 2.76 | 1.6 | 14 | <1 | 7 | 15 h |
| June | 67°F | 43°F | 55.1°F | 2.37 | 0.3 | 11 | <1 | 1 | 15 h 50 min |
| July | 78°F | 49°F | 63.5°F | 0.84 | 0.0 | 6 | 2 | <1 | 15 h 30 min |
| August | 79°F | 49°F | 63.8°F | 0.71 | 0.0 | 5 | 2 | <1 | 14 h 10 min |
| September | 70°F | 42°F | 56.1°F | 1.05 | 0.0 | 6 | <1 | 2 | 12 h 40 min |
| October | 56°F | 35°F | 45.1°F | 1.84 | 1.1 | 11 | <1 | 12 | 11 h |
| November | 43°F | 28°F | 35.2°F | 2.11 | 13.1 | 15 | <1 | 23 | 9 h 30 min |
| December | 35°F | 22°F | 28.6°F | 1.78 | 14.5 | 15 | <1 | 28 | 8 h 40 min |
| Year (annual) | 55°F | 34°F | 44.6°F | 21.77 | 86.5 | 143 | 5 | 171 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 3°C | −5°C | −1.3°C | 44 mm | 45 cm |
| February | 4°C | −5°C | −0.4°C | 39 mm | 33 cm |
| March | 7°C | −3°C | 2.3°C | 59 mm | 40 cm |
| April | 11°C | 0°C | 5.4°C | 68 mm | 23 cm |
| May | 16°C | 4°C | 9.6°C | 70 mm | 4 cm |
| June | 19°C | 6°C | 12.8°C | 60 mm | 1 cm |
| July | 26°C | 9°C | 17.5°C | 21 mm | 0 cm |
| August | 26°C | 9°C | 17.7°C | 18 mm | 0 cm |
| September | 21°C | 6°C | 13.4°C | 27 mm | 0 cm |
| October | 13°C | 1°C | 7.3°C | 47 mm | 3 cm |
| November | 6°C | −2°C | 1.8°C | 54 mm | 33 cm |
| December | 2°C | −5°C | −1.9°C | 45 mm | 37 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00109846; 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 Winchester?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, August 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 USC00109846.
When is the last frost in Winchester?
In Winchester, the last spring frost (32°F) comes after May 23 in half of years and after June 19 in one year in ten; the first autumn frost comes before September 25 in half of years and before September 7 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 231 year in 10 after June 19; 9 in 10 after May 4
- First autumn frost, half of years before
- September 251 year in 10 before September 7; 9 in 10 before October 10
NOAA puts the median frost-free season at 121 days, and the season without a hard freeze (28°F) at 160 days.
A hard freeze (28°F) comes after May 2 in half of springs and before October 9 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Winchester in zone 6b in ZIP code 83523, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Winchester's NOAA station is in zone 6a: the coldest night of a typical year reaches −6°F (23 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 USC00109846; 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 Winchester?
In a normal year in Winchester, 5 days a year reach 90°F, 171 nights fall to 32°F or colder and 143 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
- 171a normal year
- Days that stay below freezing
- 32high of 32°F or less
- Days with 0.01 inch of precipitation
- 143a normal year
- Days with 1 inch of snow or more
- 29a normal year
The highest temperature in this station's record (since 1965) is 98°F, on August 23, 1969; the lowest is −40°F, on December 30, 1968.
The wettest calendar year on that record is 1975, with 37.66 in; the snowiest season is 1971–72, with 199.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00109846; records: ACIS (NOAA Regional Climate Centers), station USC00109846. Records use complete months only; a month missing more than three days is left out.
How sunny is Winchester?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Winchester, 4.0 kWh per square metre a day. July is the sunniest month (91%) and December the cloudiest (55%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 59% | 1.3 |
| February | 64% | 2.2 |
| March | 64% | 3.3 |
| April | 70% | 4.8 |
| May | 75% | 6.0 |
| June | 78% | 6.8 |
| July | 91% | 7.5 |
| August | 88% | 6.2 |
| September | 83% | 4.5 |
| October | 73% | 2.8 |
| November | 61% | 1.5 |
| December | 55% | 1.0 |
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 Winchester need?
A normal year in Winchester brings 7,552 heating degree days, 41% more than the median U.S. place (5,373), and 140 cooling degree days, 85% 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 1,369 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,094 | 0 |
| February | 945 | 0 |
| March | 894 | 0 |
| April | 697 | 0 |
| May | 489 | 1 |
| June | 301 | 6 |
| July | 107 | 59 |
| August | 99 | 61 |
| September | 282 | 13 |
| October | 617 | 0 |
| November | 896 | 0 |
| December | 1,130 | 0 |
| Year (annual) | 7,552 | 140 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00109846. 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.
How does Winchester's climate compare?
Winchester is warmer than 28 of the other 84 places with their own NOAA record in Idaho, and wetter than 59. Across the 7,247 U.S. stations with normals, its annual mean of 44.6°F is warmer than 18%.
In the Köppen classification computed from these normals, Winchester 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 Winchester share this climate record?
3 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.
- Craigmont, ID477 people · 7 mi E
- Culdesac, ID417 people · 10 mi N
- Reubens, ID48 people · 7 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 Winchester's climate
What is the coldest month in Winchester?
December, with a normal high of 35°F and a normal low of 22°F. The warmest is August (79°F by day, 49°F at night).
Does it snow in Winchester?
Yes: 87 inches in a normal year, falling on 54 days with 0.1 inch or more, the most in January (17.9 inches).
What is the rainiest month in Winchester?
May, with 2.76 in of precipitation in a normal year; the driest is August with 0.71 in.
What plant hardiness zone is Winchester in?
The USDA's 2023 map puts Winchester in zone 6b in ZIP code 83523, the nearest ZIP area. By the same method at Winchester's NOAA station, the coldest night of a typical year reaches −6°F (23 years, 1991-2020): zone 6a.
How late can frost come in Winchester?
In half of years the last 32°F night comes after May 23; in one year in ten it comes after June 19. Waiting until June 19 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Idaho climateThe statewide normals and every place in the state
- Cottonwood, ID18 miles from this station, 47.6°F a year
- Nezperce, ID18 miles from this station, 44.9°F a year
- Lewiston, ID21 miles from this station, 53.8°F a year
- Dworshak Fish Hatchery, ID23 miles from this station, 51.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made