Nampa, Idaho climate: Normal weather by month, frost dates and records
Nampa's normal year runs from 23°F January nights to 93°F July afternoons, with 11.0 inches of precipitation and 10 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.1°C, January lows of −5°C, July highs of 34°C, 280 mm of precipitation a year.
- NOAA stationNampa Sugar Factory
- Station IDUSC00106305
- Location43.60°N 116.58°W
- Elevation2,470 ft (753 m)
- Population117,350
On October 14, the normal high in Nampa is 68°F and the normal low 37°F, and the chance of measurable rain or snow is 18%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Nampa.
- Jan 40° 23°
- Feb 47° 26°
- Mar 57° 32°
- Apr 65° 36°
- May 74° 44°
- Jun 83° 51°
- Jul 93° 57°
- Aug 92° 56°
- Sep 81° 47°
- Oct 67° 37°
- Nov 51° 28°
- Dec 40° 23°
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 Nampa each month?
July is the warmest month, with normal highs of 93°F; January the coldest, with normal lows of 23°F. The most precipitation falls in December (1.39 in), the least in August (0.20 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 40°F | 23°F | 31.2°F | 1.37 | 3.4 | 10 | <1 | 28 | 9 h 20 min |
| February | 47°F | 26°F | 36.6°F | 1.04 | 1.4 | 7 | <1 | 23 | 10 h 30 min |
| March | 57°F | 32°F | 44.5°F | 1.26 | 0.2 | 9 | <1 | 17 | 11 h 50 min |
| April | 65°F | 36°F | 50.3°F | 1.06 | 0.0 | 9 | <1 | 8 | 13 h 20 min |
| May | 74°F | 44°F | 58.9°F | 1.37 | 0.0 | 8 | 2 | 1 | 14 h 40 min |
| June | 83°F | 51°F | 66.9°F | 0.73 | 0.0 | 6 | 8 | <1 | 15 h 20 min |
| July | 93°F | 57°F | 75.3°F | 0.26 | 0.0 | 2 | 23 | <1 | 15 h 10 min |
| August | 92°F | 56°F | 73.6°F | 0.20 | 0.0 | 2 | 21 | <1 | 14 h |
| September | 81°F | 47°F | 63.8°F | 0.36 | 0.0 | 3 | 6 | <1 | 12 h 30 min |
| October | 67°F | 37°F | 51.5°F | 0.80 | 0.0 | 6 | <1 | 7 | 11 h 10 min |
| November | 51°F | 28°F | 39.5°F | 1.17 | 0.5 | 10 | <1 | 21 | 9 h 40 min |
| December | 40°F | 23°F | 31.4°F | 1.39 | 4.2 | 11 | <1 | 27 | 9 h |
| Year (annual) | 66°F | 38°F | 52.0°F | 11.01 | 9.7 | 82 | 59 | 132 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −5°C | −0.4°C | 35 mm | 9 cm |
| February | 8°C | −3°C | 2.6°C | 26 mm | 4 cm |
| March | 14°C | 0°C | 6.9°C | 32 mm | 1 cm |
| April | 18°C | 2°C | 10.2°C | 27 mm | 0 cm |
| May | 23°C | 7°C | 14.9°C | 35 mm | 0 cm |
| June | 28°C | 11°C | 19.4°C | 19 mm | 0 cm |
| July | 34°C | 14°C | 24.1°C | 7 mm | 0 cm |
| August | 33°C | 13°C | 23.1°C | 5 mm | 0 cm |
| September | 27°C | 8°C | 17.7°C | 9 mm | 0 cm |
| October | 19°C | 3°C | 10.8°C | 20 mm | 0 cm |
| November | 10°C | −2°C | 4.2°C | 30 mm | 1 cm |
| December | 4°C | −5°C | −0.3°C | 35 mm | 11 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00106305; 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 Nampa?
Normal highs sit between 65°F and 85°F in May, June, September and October. Of those, September 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 USC00106305.
When is the last frost in Nampa?
In Nampa, the last spring frost (32°F) comes after April 29 in half of years and after May 18 in one year in ten; the first autumn frost comes before October 13 in half of years and before September 29 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
- April 291 year in 10 after May 18; 9 in 10 after April 15
- First autumn frost, half of years before
- October 131 year in 10 before September 29; 9 in 10 before October 28
NOAA puts the median frost-free season at 164 days, and the season without a hard freeze (28°F) at 195 days.
A hard freeze (28°F) comes after April 11 in half of springs and before October 25 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Nampa in zone 7a across its 3 ZIP code areas (7a in 83687, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Nampa's NOAA station is in zone 7a: the coldest night of a typical year reaches 4°F (21 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 USC00106305; 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.
What hardiness zone is each Nampa ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Nampa's 3 ZIP code areas are all in zone 7a. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Nampa?
In a normal year in Nampa, 59 days a year reach 90°F (10 of them 100°F or more), 132 nights fall to 32°F or colder and 82 days bring measurable precipitation.
- Days at 90°F or more
- 59a normal year
- Days at 100°F or more
- 10a normal year
- Nights at 32°F or colder
- 132a normal year
- Days that stay below freezing
- 13high of 32°F or less
- Days with 0.01 inch of precipitation
- 82a normal year
- Days with 1 inch of snow or more
- 5a normal year
The highest temperature in this station's record (since 1976) is 109°F, on June 29, 2015; the lowest is −26°F, on December 22, 1990.
The wettest calendar year on that record is 1983, with 17.67 in; the snowiest season is 1992–93, with 30.1 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00106305; records: ACIS (NOAA Regional Climate Centers), station USC00106305. Records use complete months only; a month missing more than three days is left out.
How sunny is Nampa?
Over a year 82% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Nampa, 4.6 kWh per square metre a day. July is the sunniest month (92%) and December the cloudiest (62%). Among the 459 U.S. places of 50,000 or more, that ranks tied 99th (with 11 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 64% | 1.7 |
| February | 70% | 2.7 |
| March | 72% | 4.0 |
| April | 77% | 5.5 |
| May | 81% | 6.7 |
| June | 86% | 7.5 |
| July | 92% | 7.7 |
| August | 92% | 6.7 |
| September | 89% | 5.2 |
| October | 82% | 3.5 |
| November | 71% | 2.1 |
| December | 62% | 1.4 |
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 Nampa need?
A normal year in Nampa brings 5,549 heating degree days, 3% more than the median U.S. place (5,373), and 825 cooling degree days, 9% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,956 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,046 | 0 |
| February | 795 | 0 |
| March | 636 | 0 |
| April | 442 | 2 |
| May | 219 | 31 |
| June | 65 | 122 |
| July | 6 | 325 |
| August | 10 | 275 |
| September | 106 | 68 |
| October | 420 | 3 |
| November | 763 | 0 |
| December | 1,041 | 0 |
| Year (annual) | 5,549 | 825 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00106305. 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 Nampa's climate compare?
Nampa is warmer than 75 of the other 84 places with their own NOAA record in Idaho, and wetter than 25. Across the 7,247 U.S. stations with normals, its annual mean of 52.0°F is warmer than 49%.
In the Köppen classification computed from these normals, Nampa 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 Nampa 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.
- Caldwell, IDalso near: Deer Flat Dam (7 mi, 52.5°F a year); Homedale (13 mi, 51.8°F a year)73,088 people · 5 mi NW
- Star, ID18,208 people · 8 mi NE
- Middleton, ID11,730 people · 8 mi N
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 Nampa's climate
What is the coldest month in Nampa?
January, with a normal high of 40°F and a normal low of 23°F. The warmest is July (93°F by day, 57°F at night).
Does it snow in Nampa?
Yes: 10 inches in a normal year, falling on 10 days with 0.1 inch or more, the most in December (4.2 inches).
What is the rainiest month in Nampa?
December, with 1.39 in of precipitation in a normal year; the driest is August with 0.20 in.
What plant hardiness zone is Nampa in?
The USDA's 2023 map puts Nampa in zone 7a across its 3 ZIP code areas (7a in 83687, the largest). By the same method at Nampa's NOAA station, the coldest night of a typical year reaches 4°F (21 years, 1991-2020): zone 7a.
How late can frost come in Nampa?
In half of years the last 32°F night comes after April 29; in one year in ten it comes after May 18. Waiting until May 18 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Nampa in OctoberThis month day by day, its records and recent years
- Idaho climateThe statewide normals and every place in the state
- Deer Flat Dam, ID9 miles from this station, 52.5°F a year
- Boise, ID17 miles from this station, 53.2°F a year
- Homedale, ID17 miles from this station, 51.8°F a year
- Emmett, ID18 miles from this station, 51.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made