Napoleon, North Dakota climate: Normal weather by month, frost dates and records
Napoleon's normal year runs from 1°F January nights to 82°F July afternoons, with 20.7 inches of precipitation and 53 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 5.1°C, January lows of −17°C, July highs of 28°C, 527 mm of precipitation a year.
- NOAA stationNapoleon
- Station IDUSC00326255
- Location46.51°N 99.77°W
- Elevation1,980 ft (604 m)
- Population746
On October 22, the normal high in Napoleon is 52°F and the normal low 30°F, and the chance of measurable rain or snow is 20%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Napoleon.
- Jan 20° 1°
- Feb 24° 4°
- Mar 37° 16°
- Apr 53° 29°
- May 66° 42°
- Jun 75° 53°
- Jul 82° 58°
- Aug 81° 55°
- Sep 71° 46°
- Oct 55° 33°
- Nov 38° 19°
- Dec 25° 8°
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 Napoleon each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 1°F. The most precipitation falls in June (3.83 in), the least in January (0.55 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 20°F | 1°F | 10.2°F | 0.55 | 9.6 | 7 | <1 | 31 | 9 h |
| February | 24°F | 4°F | 14.2°F | 0.56 | 7.9 | 6 | <1 | 28 | 10 h 20 min |
| March | 37°F | 16°F | 26.5°F | 0.93 | 9.2 | 6 | <1 | 29 | 11 h 50 min |
| April | 53°F | 29°F | 40.8°F | 1.69 | 5.7 | 7 | <1 | 20 | 13 h 30 min |
| May | 66°F | 42°F | 53.8°F | 2.82 | 0.7 | 10 | <1 | 5 | 15 h |
| June | 75°F | 53°F | 64.1°F | 3.83 | 0.0 | 11 | 1 | <1 | 15 h 50 min |
| July | 82°F | 58°F | 69.6°F | 3.06 | 0.0 | 9 | 5 | <1 | 15 h 30 min |
| August | 81°F | 55°F | 68.0°F | 2.40 | 0.0 | 7 | 4 | <1 | 14 h 20 min |
| September | 71°F | 46°F | 58.6°F | 1.79 | 0.0 | 7 | 1 | 2 | 12 h 40 min |
| October | 55°F | 33°F | 43.9°F | 1.73 | 2.5 | 7 | <1 | 16 | 11 h |
| November | 38°F | 19°F | 28.5°F | 0.66 | 6.6 | 5 | <1 | 28 | 9 h 30 min |
| December | 25°F | 8°F | 16.3°F | 0.71 | 11.0 | 6 | <1 | 31 | 8 h 40 min |
| Year (annual) | 52°F | 30°F | 41.2°F | 20.73 | 53.2 | 87 | 11 | 188 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −7°C | −17°C | −12.1°C | 14 mm | 24 cm |
| February | −4°C | −16°C | −9.9°C | 14 mm | 20 cm |
| March | 3°C | −9°C | −3.1°C | 24 mm | 23 cm |
| April | 12°C | −2°C | 4.9°C | 43 mm | 14 cm |
| May | 19°C | 5°C | 12.1°C | 72 mm | 2 cm |
| June | 24°C | 12°C | 17.8°C | 97 mm | 0 cm |
| July | 28°C | 14°C | 20.9°C | 78 mm | 0 cm |
| August | 27°C | 13°C | 20.0°C | 61 mm | 0 cm |
| September | 22°C | 8°C | 14.8°C | 45 mm | 0 cm |
| October | 13°C | 0°C | 6.6°C | 44 mm | 6 cm |
| November | 4°C | −7°C | −1.9°C | 17 mm | 17 cm |
| December | −4°C | −14°C | −8.7°C | 18 mm | 28 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00326255; 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 Napoleon?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, August has the fewest days with rain (7).
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 USC00326255.
When is the last frost in Napoleon?
In Napoleon, the last spring frost (32°F) comes after May 13 in half of years and after May 26 in one year in ten; the first autumn frost comes before September 28 in half of years and before September 15 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 131 year in 10 after May 26; 9 in 10 after May 1
- First autumn frost, half of years before
- September 281 year in 10 before September 15; 9 in 10 before October 11
NOAA puts the median frost-free season at 136 days, and the season without a hard freeze (28°F) at 153 days.
A hard freeze (28°F) comes after May 4 in half of springs and before October 6 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Napoleon in zone 4a in ZIP code 58561, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Napoleon's NOAA station is in zone 4a: the coldest night of a typical year reaches −27°F (23 complete years).
Frost dates for every NOAA station in North Dakota · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00326255; 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 Napoleon?
In a normal year in Napoleon, 11 days a year reach 90°F (1 of them 100°F or more), 188 nights fall to 32°F or colder and 87 days bring measurable precipitation.
- Days at 90°F or more
- 11a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 188a normal year
- Days that stay below freezing
- 90high of 32°F or less
- Days with 0.01 inch of precipitation
- 87a normal year
- Days with 1 inch of snow or more
- 18a normal year
The highest temperature in this station's record (since 1893) is 118°F, on July 6, 1936; the lowest is −48°F, on December 20, 1916.
The wettest calendar year on that record is 1993, with 28.41 in; the snowiest season is 1996–97, with 108.4 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00326255; records: ACIS (NOAA Regional Climate Centers), station USC00326255. Records use complete months only; a month missing more than three days is left out.
How sunny is Napoleon?
Over a year 77% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Napoleon, 4.0 kWh per square metre a day. February is the sunniest month (84%) and November the cloudiest (70%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 81% | 1.9 |
| February | 84% | 3.0 |
| March | 77% | 4.0 |
| April | 73% | 5.0 |
| May | 72% | 5.7 |
| June | 76% | 6.4 |
| July | 84% | 6.6 |
| August | 82% | 5.5 |
| September | 78% | 4.2 |
| October | 70% | 2.7 |
| November | 70% | 1.7 |
| December | 70% | 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 Napoleon need?
A normal year in Napoleon brings 9,065 heating degree days, 69% more than the median U.S. place (5,373), and 441 cooling degree days, 51% 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 2,158 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,700 | 0 |
| February | 1,422 | 0 |
| March | 1,192 | 0 |
| April | 725 | 0 |
| May | 360 | 14 |
| June | 99 | 72 |
| July | 27 | 172 |
| August | 46 | 140 |
| September | 233 | 40 |
| October | 654 | 2 |
| November | 1,095 | 0 |
| December | 1,511 | 0 |
| Year (annual) | 9,065 | 441 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00326255. 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 Napoleon been warmer than normal lately?
Over 98 complete years from 1891 to 2024, the station's annual mean temperature rose at a fitted 1.9°F per century (+0.11°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Napoleon's climate compare?
Napoleon is warmer than 45 of the other 91 places with their own NOAA record in North Dakota, and wetter than 54. Across the 7,247 U.S. stations with normals, its annual mean of 41.2°F is warmer than 8%.
In the Köppen classification computed from these normals, Napoleon is Dfb: continental, no dry season, 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.
Questions about Napoleon's climate
What is the coldest month in Napoleon?
January, with a normal high of 20°F and a normal low of 1°F. The warmest is July (82°F by day, 58°F at night).
Does it snow in Napoleon?
Yes: 53 inches in a normal year, falling on 31 days with 0.1 inch or more, the most in December (11.0 inches).
What is the rainiest month in Napoleon?
June, with 3.83 in of precipitation in a normal year; the driest is January with 0.55 in.
What plant hardiness zone is Napoleon in?
The USDA's 2023 map puts Napoleon in zone 4a in ZIP code 58561, the nearest ZIP area. By the same method at Napoleon's NOAA station, the coldest night of a typical year reaches −27°F (23 years, 1991-2020): zone 4a.
How late can frost come in Napoleon?
In half of years the last 32°F night comes after May 13; in one year in ten it comes after May 26. Waiting until May 26 leaves about a one-in-ten chance of a later frost.
Nearby and next
- North Dakota climateThe statewide normals and every place in the state
- Wishek, ND20 miles from this station, 41.2°F a year
- Streeter, ND21 miles from this station, 40.9°F a year
- Jamestown (38 mi WSW), ND23 miles from this station, 40.3°F a year
- Moffit (3 mi SE), ND25 miles from this station, 43.6°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made