Sidney, Montana climate: Normal weather by month, frost dates and records
Sidney's normal year runs from 7°F January nights to 87°F July afternoons, with 15.5 inches of precipitation and 30 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.3°C, January lows of −14°C, July highs of 30°C, 394 mm of precipitation a year.
- NOAA stationSidney
- Station IDUSC00247560
- Location47.73°N 104.15°W
- Elevation1,933 ft (589 m)
- Population6,031
On October 22, the normal high in Sidney is 56°F and the normal low 31°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 Sidney.
- Jan 27° 7°
- Feb 32° 11°
- Mar 46° 21°
- Apr 61° 32°
- May 71° 43°
- Jun 79° 52°
- Jul 87° 57°
- Aug 86° 55°
- Sep 76° 46°
- Oct 59° 34°
- Nov 42° 21°
- Dec 31° 11°
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 Sidney each month?
July is the warmest month, with normal highs of 87°F; January the coldest, with normal lows of 7°F. The most precipitation falls in June (2.78 in), the least in February (0.37 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 27°F | 7°F | 16.9°F | 0.45 | 7.0 | 7 | <1 | 30 | 8 h 50 min |
| February | 32°F | 11°F | 21.3°F | 0.37 | 5.6 | 5 | <1 | 28 | 10 h 10 min |
| March | 46°F | 21°F | 33.4°F | 0.58 | 3.0 | 6 | <1 | 27 | 11 h 50 min |
| April | 61°F | 32°F | 46.1°F | 1.17 | 1.7 | 6 | <1 | 16 | 13 h 30 min |
| May | 71°F | 43°F | 57.0°F | 2.40 | 0.7 | 10 | 1 | 4 | 15 h 10 min |
| June | 79°F | 52°F | 65.7°F | 2.78 | 0.0 | 11 | 3 | <1 | 16 h |
| July | 87°F | 57°F | 72.0°F | 2.65 | 0.0 | 9 | 12 | <1 | 15 h 40 min |
| August | 86°F | 55°F | 70.8°F | 1.30 | 0.0 | 7 | 11 | <1 | 14 h 20 min |
| September | 76°F | 46°F | 60.6°F | 1.62 | 0.0 | 7 | 3 | 2 | 12 h 40 min |
| October | 59°F | 34°F | 46.5°F | 1.08 | 1.5 | 7 | <1 | 14 | 11 h |
| November | 42°F | 21°F | 31.6°F | 0.59 | 3.0 | 5 | <1 | 27 | 9 h 20 min |
| December | 31°F | 11°F | 20.6°F | 0.51 | 7.9 | 6 | <1 | 31 | 8 h 30 min |
| Year (annual) | 58°F | 32°F | 45.2°F | 15.50 | 30.4 | 85 | 30 | 178 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −3°C | −14°C | −8.4°C | 11 mm | 18 cm |
| February | 0°C | −12°C | −5.9°C | 9 mm | 14 cm |
| March | 8°C | −6°C | 0.8°C | 15 mm | 8 cm |
| April | 16°C | 0°C | 7.8°C | 30 mm | 4 cm |
| May | 22°C | 6°C | 13.9°C | 61 mm | 2 cm |
| June | 26°C | 11°C | 18.7°C | 71 mm | 0 cm |
| July | 30°C | 14°C | 22.2°C | 67 mm | 0 cm |
| August | 30°C | 13°C | 21.6°C | 33 mm | 0 cm |
| September | 24°C | 8°C | 15.9°C | 41 mm | 0 cm |
| October | 15°C | 1°C | 8.1°C | 27 mm | 4 cm |
| November | 5°C | −6°C | −0.2°C | 15 mm | 8 cm |
| December | −1°C | −12°C | −6.3°C | 13 mm | 20 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00247560; 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 Sidney?
Normal highs sit between 65°F and 85°F in May, June and September. Of those, September 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 USC00247560.
When is the last frost in Sidney?
In Sidney, the last spring frost (32°F) comes after May 11 in half of years and after May 25 in one year in ten; the first autumn frost comes before September 27 in half of years and before September 13 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 111 year in 10 after May 25; 9 in 10 after April 30
- First autumn frost, half of years before
- September 271 year in 10 before September 13; 9 in 10 before October 9
NOAA puts the median frost-free season at 137 days, and the season without a hard freeze (28°F) at 155 days.
A hard freeze (28°F) comes after May 2 in half of springs and before October 6 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Sidney in zone 4a in ZIP code 59270, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Sidney's NOAA station is in zone 4a: the coldest night of a typical year reaches −26°F (26 complete years).
Frost dates for every NOAA station in Montana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00247560; 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 Sidney?
In a normal year in Sidney, 30 days a year reach 90°F (1 of them 100°F or more), 178 nights fall to 32°F or colder and 85 days bring measurable precipitation.
- Days at 90°F or more
- 30a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 178a normal year
- Days that stay below freezing
- 62high of 32°F or less
- Days with 0.01 inch of precipitation
- 85a normal year
- Days with 1 inch of snow or more
- 13a normal year
The highest temperature in this station's record (since 1910) is 110°F, on July 27, 1917; the lowest is −47°F, on January 11, 1912.
The wettest calendar year on that record is 2019, with 24.11 in; the snowiest season is 1978–79, with 75.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00247560; records: ACIS (NOAA Regional Climate Centers), station USC00247560. Records use complete months only; a month missing more than three days is left out.
How sunny is Sidney?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Sidney, 4.0 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (70%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 77% | 1.7 |
| February | 79% | 2.7 |
| March | 75% | 3.8 |
| April | 72% | 4.9 |
| May | 74% | 5.9 |
| June | 79% | 6.7 |
| July | 87% | 7.0 |
| August | 85% | 5.8 |
| September | 79% | 4.2 |
| October | 74% | 2.7 |
| November | 72% | 1.7 |
| December | 70% | 1.2 |
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 Sidney need?
A normal year in Sidney brings 7,770 heating degree days, 45% more than the median U.S. place (5,373), and 593 cooling degree days, 35% 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 2,537 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,493 | 0 |
| February | 1,224 | 0 |
| March | 980 | 0 |
| April | 567 | 2 |
| May | 270 | 22 |
| June | 68 | 89 |
| July | 11 | 226 |
| August | 24 | 202 |
| September | 180 | 49 |
| October | 577 | 3 |
| November | 1,004 | 0 |
| December | 1,375 | 0 |
| Year (annual) | 7,770 | 593 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00247560. 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 Sidney been warmer than normal lately?
2024 averaged 52.6°F, 7.4°F above the 1991-2020 normal of 45.2°F.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2024 | 52.6°F | +7.4°F | 10.18 | 22.5 |
Over 63 complete years from 1950 to 2020, the station's annual mean temperature rose at a fitted 5.6°F per century (+0.31°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00247560; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Sidney's climate compare?
Sidney is warmer than 96 of the other 140 places with their own NOAA record in Montana, and wetter than 83. Across the 7,247 U.S. stations with normals, its annual mean of 45.2°F is warmer than 20%.
In the Köppen classification computed from these normals, Sidney 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 Sidney 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.
- Fairview, MT854 people · 10 mi NE
- Alexander, ND317 people · 25 mi E
- East Fairview, ND134 people · 10 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 Sidney's climate
What is the coldest month in Sidney?
January, with a normal high of 27°F and a normal low of 7°F. The warmest is July (87°F by day, 57°F at night).
Does it snow in Sidney?
Yes: 30 inches in a normal year, falling on 24 days with 0.1 inch or more, the most in December (7.9 inches).
What is the rainiest month in Sidney?
June, with 2.78 in of precipitation in a normal year; the driest is February with 0.37 in.
What plant hardiness zone is Sidney in?
The USDA's 2023 map puts Sidney in zone 4a in ZIP code 59270, the nearest ZIP area. By the same method at Sidney's NOAA station, the coldest night of a typical year reaches −26°F (26 years, 1991-2020): zone 4a.
How late can frost come in Sidney?
In half of years the last 32°F night comes after May 11; in one year in ten it comes after May 25. Waiting until May 25 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Savage, MT21 miles from this station, 45.8°F a year
- Trotters (3 mi SSE), ND33 miles from this station, 43.6°F a year
- Culbertson, MT34 miles from this station, 43.3°F a year
- Williston, ND39 miles from this station, 41.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made