USDA Hardiness Zone 4a
Frost Dates for 59417 — Browning, Montana
NOAA 1991–2020 normals from E Glacier, MT (4,806 ft), 10 miles southwest.
Updated
In Browning, the last spring frost (32°F) is around June 8 in half of years and has passed by July 1 in nine years out of ten. The first fall frost comes around September 5, as early as August 20 one year in ten, leaving a typical freeze-free season of 88 days (NOAA, E Glacier, MT).
- Last spring frost
- June 8
- First fall frost
- September 5
- Growing season
- 88 days
- Hardiness zone
- 4a
50% probability
50% probability
freeze-free, 50%
-30 to -25°F (-34.4 to -31.7°C) coldest night
- First snow
- October 10
- Last snow
- May 5
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
29 of 29 observed
NOAA normal
Frost risk by date in Browning
Half of springs at E Glacier, MT see their last 32°F night by June 8; only one in ten is past it by May 24, and one in ten still has one after July 1. Planting tender crops after June 17 leaves a 30% risk of a frost on them, after June 22 20%, and after July 1 10%. The 23 days between the even-odds date and the one-in-ten date is wider than at 99% of the 68 Montana stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.
In fall the first 32°F night comes by September 5 in half of years, as early as August 20 one year in ten, and holds off past September 20 one year in ten. A hard freeze of 28°F follows 18 days later, around September 23; in spring the one-in-ten date for 28°F is June 7, 24 days before the 32°F one. The freeze-free season lasts 88 days in a typical year, shorter than at 94% of the 68 Montana stations; it reaches 110 days one year in ten and falls short of 60 one year in ten. On average 201 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between October 25 and April 12.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | May 24 | May 29 | Jun 1 | Jun 4 | Jun 8 | Jun 13 | Jun 17 | Jun 22 | Jul 1 |
| 28°F | May 7 | May 12 | May 15 | May 18 | May 21 | May 24 | May 28 | May 31 | Jun 7 |
| 24°F | Apr 20 | Apr 27 | Apr 30 | May 3 | May 6 | May 8 | May 12 | May 16 | May 24 |
| 20°F | Apr 5 | Apr 12 | Apr 17 | Apr 20 | Apr 24 | Apr 28 | Apr 30 | May 4 | May 11 |
| 16°F | Mar 27 | Apr 2 | Apr 5 | Apr 8 | Apr 12 | Apr 16 | Apr 19 | Apr 24 | Apr 29 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Aug 20 | Aug 27 | Aug 31 | Sep 2 | Sep 5 | Sep 8 | Sep 11 | Sep 15 | Sep 20 |
| 28°F | Sep 4 | Sep 12 | Sep 16 | Sep 20 | Sep 23 | Sep 26 | Sep 29 | Oct 1 | Oct 5 |
| 24°F | Sep 21 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 12 | Oct 16 | Oct 21 |
| 20°F | Sep 30 | Oct 3 | Oct 8 | Oct 12 | Oct 16 | Oct 18 | Oct 23 | Oct 28 | Nov 1 |
| 16°F | Oct 5 | Oct 12 | Oct 17 | Oct 21 | Oct 25 | Oct 29 | Nov 1 | Nov 5 | Nov 10 |
Freeze probabilities 1991–2020 at E Glacier, MT, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 59417 →Compare Browning with another place →
Weather by month in Browning
July is the warmest month at E Glacier, MT, averaging 74°F by day and 46°F at night; January is the coldest at 30°F and 13°F. A freezing night is all but certain in every month from September to May (a 90% chance or more). No month is safe from a 32°F night: even the warmest has at least a 10% chance. In spring, June still brings one in 67% of years and July still brings one in 10% of years.
Warmth for growing adds up to 903 growing degree days a year (base 50°F), the fewest of the 68 Montana stations. 18% of them (166) have built up by the end of June, and July adds the most, 312.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 30 | 13 | 100% | 29 | 0 |
| Feb | 31 | 13 | 100% | 26 | 0 |
| Mar | 37 | 19 | 100% | 28 | 0 |
| Apr | 46 | 27 | 100% | 24 | 3 |
| May | 56 | 34 | 100% | 13 | 41 |
| Jun | 64 | 41 | 67% | 2 | 122 |
| Jul | 74 | 46 | 10% | <1 | 312 |
| Aug | 74 | 44 | 31% | 1 | 297 |
| Sep | 63 | 38 | 99% | 6 | 107 |
| Oct | 50 | 29 | 100% | 19 | 19 |
| Nov | 36 | 22 | 100% | 25 | 1 |
| Dec | 29 | 15 | 100% | 29 | 0 |
Monthly normals 1991–2020 at E Glacier, MT (4,806 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Cut Bank Municipal Airport, MT, 32 miles east of Browning and 968 feet lower, has a last frost 15 days earlier (May 24), a first frost 10 days later (September 15), a season 25 days longer.
When it snows in Browning, Montana
The first measurable snow (0.1 inch or more) in Browning usually arrives around October 10, and the last of the season around May 5. Those are the middle dates across the winters of 1991–2020 at E Glacier, MT, 10.3 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 34 days after the last snow.
Planting calendar for 59417
| When | What to do |
|---|---|
| March 30 – April 13 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| April 13 – April 27 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| May 11 – May 25 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| June 8 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 13 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by August 22 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 5 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 59417 is 10 miles from E Glacier, MT, which stands at 4,806 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 59417 in zone 4a, the band where the coldest night of the year averaged -30 to -25°F (-34.4 to -31.7°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.