Heron, Montana climate: Normal weather by month, frost dates and records
Heron's normal year runs from 23°F December nights to 82°F July afternoons, with 34.2 inches of precipitation and 84 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.3°C, December lows of −5°C, July highs of 28°C, 869 mm of precipitation a year.
- NOAA stationHeron (2 mi NW)
- Station IDUSC00244084
- Location48.08°N 116.00°W
- Elevation2,240 ft (683 m)
- Population (census place)312
On October 23, the normal high in Heron is 51°F and the normal low 32°F, and the chance of measurable rain or snow is 45%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Heron.
- Jan 33° 23°
- Feb 38° 23°
- Mar 47° 27°
- Apr 57° 32°
- May 67° 39°
- Jun 73° 45°
- Jul 82° 47°
- Aug 82° 46°
- Sep 71° 40°
- Oct 55° 34°
- Nov 40° 29°
- Dec 32° 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 Heron each month?
July is the warmest month, with normal highs of 82°F; December the coldest, with normal lows of 23°F. The most precipitation falls in January (4.51 in), the least in August (0.89 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 33°F | 23°F | 28.0°F | 4.51 | 26.5 | 18 | <1 | 29 | 8 h 50 min |
| February | 38°F | 23°F | 30.5°F | 2.92 | 12.3 | 13 | <1 | 26 | 10 h 10 min |
| March | 47°F | 27°F | 36.7°F | 3.26 | 10.9 | 14 | <1 | 26 | 11 h 50 min |
| April | 57°F | 32°F | 44.0°F | 2.72 | 1.3 | 13 | <1 | 17 | 13 h 40 min |
| May | 67°F | 39°F | 52.9°F | 2.76 | 0.1 | 13 | <1 | 7 | 15 h 10 min |
| June | 73°F | 45°F | 58.6°F | 2.99 | 0.0 | 13 | 1 | 1 | 16 h |
| July | 82°F | 47°F | 64.5°F | 1.12 | 0.0 | 7 | 5 | <1 | 15 h 40 min |
| August | 82°F | 46°F | 63.8°F | 0.89 | 0.0 | 6 | 5 | <1 | 14 h 20 min |
| September | 71°F | 40°F | 55.5°F | 1.62 | 0.0 | 9 | <1 | 4 | 12 h 40 min |
| October | 55°F | 34°F | 44.1°F | 3.11 | 0.7 | 13 | <1 | 14 | 11 h |
| November | 40°F | 29°F | 34.7°F | 4.14 | 7.9 | 16 | <1 | 22 | 9 h 20 min |
| December | 32°F | 23°F | 27.7°F | 4.19 | 24.6 | 18 | <1 | 29 | 8 h 20 min |
| Year (annual) | 56°F | 34°F | 45.1°F | 34.23 | 84.3 | 154 | 12 | 174 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 1°C | −5°C | −2.2°C | 115 mm | 67 cm |
| February | 3°C | −5°C | −0.8°C | 74 mm | 31 cm |
| March | 8°C | −3°C | 2.6°C | 83 mm | 28 cm |
| April | 14°C | 0°C | 6.7°C | 69 mm | 3 cm |
| May | 19°C | 4°C | 11.6°C | 70 mm | 0 cm |
| June | 23°C | 7°C | 14.8°C | 76 mm | 0 cm |
| July | 28°C | 8°C | 18.1°C | 28 mm | 0 cm |
| August | 28°C | 8°C | 17.7°C | 23 mm | 0 cm |
| September | 22°C | 5°C | 13.1°C | 41 mm | 0 cm |
| October | 13°C | 1°C | 6.7°C | 79 mm | 2 cm |
| November | 5°C | −2°C | 1.5°C | 105 mm | 20 cm |
| December | 0°C | −5°C | −2.4°C | 106 mm | 62 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00244084; 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 Heron?
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 (6).
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 USC00244084.
When is the last frost in Heron?
In Heron, the last spring frost (32°F) comes after May 20 in half of years and after June 5 in one year in ten; the first autumn frost comes before September 20 in half of years and before September 1 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 201 year in 10 after June 5; 9 in 10 after May 4
- First autumn frost, half of years before
- September 201 year in 10 before September 1; 9 in 10 before October 5
NOAA puts the median frost-free season at 119 days, and the season without a hard freeze (28°F) at 157 days.
A hard freeze (28°F) comes after May 2 in half of springs and before October 7 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Heron in zone 6b in ZIP code 59844, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Heron's NOAA station is in zone 6a: the coldest night of a typical year reaches −6°F (30 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 Montana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00244084; 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 Heron?
In a normal year in Heron, 12 days a year reach 90°F, 174 nights fall to 32°F or colder and 154 days bring measurable precipitation.
- Days at 90°F or more
- 12a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 174a normal year
- Days that stay below freezing
- 35high of 32°F or less
- Days with 0.01 inch of precipitation
- 154a normal year
- Days with 1 inch of snow or more
- 27a normal year
The highest temperature in this station's record (since 1912) is 106°F, on August 4, 1961; the lowest is −39°F, on January 21, 1927.
The wettest calendar year on that record is 1933, with 50.33 in; the snowiest season is 2007–08, with 173.3 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00244084; records: ACIS (NOAA Regional Climate Centers), station USC00244084. Records use complete months only; a month missing more than three days is left out.
How sunny is Heron?
Over a year 71% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Heron, 3.6 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (48%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 50% | 1.0 |
| February | 60% | 1.9 |
| March | 59% | 2.9 |
| April | 65% | 4.4 |
| May | 71% | 5.7 |
| June | 70% | 6.0 |
| July | 87% | 7.2 |
| August | 86% | 5.9 |
| September | 79% | 4.2 |
| October | 68% | 2.4 |
| November | 53% | 1.2 |
| December | 48% | 0.8 |
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 Heron need?
A normal year in Heron brings 7,364 heating degree days, 37% more than the median U.S. place (5,373), and 130 cooling degree days, 86% 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 1,491 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,145 | 0 |
| February | 967 | 0 |
| March | 877 | 0 |
| April | 629 | 0 |
| May | 378 | 2 |
| June | 202 | 12 |
| July | 76 | 61 |
| August | 89 | 53 |
| September | 289 | 4 |
| October | 646 | 0 |
| November | 908 | 0 |
| December | 1,158 | 0 |
| Year (annual) | 7,364 | 130 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00244084. 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 Heron been warmer than normal lately?
2025 averaged 47.9°F, 2.8°F above the 1991-2020 normal of 45.1°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 46.9°F | +1.8°F | 31.19 | 99.2 |
| 2022 | 44.7°F | −0.4°F | 36.83 | 94.8 |
| 2023 | 47.0°F | +1.9°F | 23.42 | 50.5 |
| 2024 | 46.8°F | +1.7°F | 31.37 | 58.8 |
| 2025 | 47.9°F | +2.8°F | 34.37 | 50.6 |
Over 85 complete years from 1913 to 2025, the station's annual mean temperature rose at a fitted 1.6°F per century (+0.09°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00244084; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Heron's climate compare?
Heron is warmer than 93 of the other 140 places with their own NOAA record in Montana, and wetter than 130. Across the 7,247 U.S. stations with normals, its annual mean of 45.1°F is warmer than 20%.
In the Köppen classification computed from these normals, Heron 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 Heron 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.
- Clark Fork, ID576 people · 9 mi NW
- East Hope, ID250 people · 17 mi NW
- Hope, ID107 people · 18 mi NW
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 Heron's climate
What is the coldest month in Heron?
December, with a normal high of 32°F and a normal low of 23°F. The warmest is July (82°F by day, 47°F at night).
Does it snow in Heron?
Yes: 84 inches in a normal year, falling on 47 days with 0.1 inch or more, the most in January (26.5 inches).
What is the rainiest month in Heron?
January, with 4.51 in of precipitation in a normal year; the driest is August with 0.89 in.
What plant hardiness zone is Heron in?
The USDA's 2023 map puts Heron in zone 6b in ZIP code 59844, the nearest ZIP area. By the same method at Heron's NOAA station, the coldest night of a typical year reaches −6°F (30 years, 1991-2020): zone 6a.
How late can frost come in Heron?
In half of years the last 32°F night comes after May 20; in one year in ten it comes after June 5. Waiting until June 5 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Cabinet Gorge, ID2 miles from this station, 46.2°F a year
- Trout Creek, MT23 miles from this station, 46.1°F a year
- Bayview Model Basin, ID27 miles from this station, 45.0°F a year
- Troy, MT28 miles from this station, 46.8°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made