USDA Hardiness Zone 4a
Frost Dates for 59330 — Glendive, Montana
NOAA 1991–2020 normals from Glendive, MT (2,075 ft), under a mile east.
Updated
In Glendive, the last spring frost (32°F) is around May 3 in half of years and has passed by May 16 in nine years out of ten. The first fall frost comes around October 4, as early as September 22 one year in ten, leaving a typical freeze-free season of 153 days (NOAA, Glendive, MT).
- Last spring frost
- May 3
- First fall frost
- October 4
- Growing season
- 153 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
- November 6
- Last snow
- April 4
- Winters with snow
- 100%
- Snow per year
- 22.6"
median, 1991–2020
median, 1991–2020
25 of 25 observed
NOAA normal
Frost risk by date in Glendive
Half of springs at Glendive, MT see their last 32°F night by May 3; only one in ten is past it by April 19, and one in ten still has one after May 16. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 12 20%, and after May 16 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 74% of the 68 Montana stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 4 in half of years, as early as September 22 one year in ten, and holds off past October 17 one year in ten. A hard freeze of 28°F follows 9 days later, around October 13; in spring the one-in-ten date for 28°F is May 8, 8 days before the 32°F one. The freeze-free season lasts 153 days in a typical year, longer than at 97% of the 68 Montana stations; it reaches 171 days one year in ten and falls short of 134 one year in ten. On average 166 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 11 days longer, to about May 14, and return around September 26. Severe cold of 16°F or below comes every winter, usually between November 9 and March 26.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 2 | May 5 | May 8 | May 11 | May 14 | May 16 | May 19 | May 22 | May 27 |
| 32°F | Apr 19 | Apr 24 | Apr 29 | May 1 | May 3 | May 6 | May 8 | May 12 | May 16 |
| 28°F | Apr 9 | Apr 14 | Apr 18 | Apr 21 | Apr 24 | Apr 27 | Apr 30 | May 3 | May 8 |
| 24°F | Mar 30 | Apr 3 | Apr 6 | Apr 9 | Apr 12 | Apr 16 | Apr 19 | Apr 24 | Apr 29 |
| 20°F | Mar 16 | Mar 24 | Mar 30 | Apr 2 | Apr 4 | Apr 7 | Apr 10 | Apr 14 | Apr 19 |
| 16°F | Mar 7 | Mar 12 | Mar 17 | Mar 22 | Mar 26 | Mar 30 | Apr 3 | Apr 6 | Apr 11 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 12 | Sep 18 | Sep 21 | Sep 23 | Sep 26 | Sep 28 | Sep 30 | Oct 3 | Oct 7 |
| 32°F | Sep 22 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 17 |
| 28°F | Sep 30 | Oct 4 | Oct 8 | Oct 11 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 27 |
| 24°F | Oct 8 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 29 | Nov 1 | Nov 6 |
| 20°F | Oct 17 | Oct 23 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 17 |
| 16°F | Oct 28 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 20 | Nov 24 |
Freeze probabilities 1991–2020 at Glendive, 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 59330 →Compare Glendive with another place →
Weather by month in Glendive
July is the warmest month at Glendive, MT, averaging 88°F by day and 60°F at night; January is the coldest at 29°F and 9°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 60% of years.
Warmth for growing adds up to 2,733 growing degree days a year (base 50°F), the most of the 68 Montana stations. 30% of them (821) have built up by the end of June, and July adds the most, 744. Precipitation totals 14.9 inches a year, most in May (2.6") and least in January (0.4"); May to September bring 68% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 29 | 9 | 0.4 | 100% | 30 | 0 |
| Feb | 34 | 13 | 0.4 | 100% | 27 | 1 |
| Mar | 46 | 23 | 0.5 | 100% | 26 | 12 |
| Apr | 59 | 34 | 1.5 | 100% | 13 | 69 |
| May | 69 | 45 | 2.6 | 60% | 2 | 247 |
| Jun | 79 | 54 | 2.4 | 0% | 0 | 493 |
| Jul | 88 | 60 | 2.2 | 0% | 0 | 744 |
| Aug | 87 | 58 | 1.5 | 0% | 0 | 698 |
| Sep | 76 | 48 | 1.4 | 35% | 1 | 375 |
| Oct | 60 | 36 | 1.1 | 100% | 11 | 89 |
| Nov | 44 | 24 | 0.5 | 100% | 25 | 7 |
| Dec | 32 | 13 | 0.4 | 100% | 30 | 0 |
Monthly normals 1991–2020 at Glendive, MT (2,075 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
When it snows in Glendive, Montana
The first measurable snow (0.1 inch or more) in Glendive usually arrives around November 6, and the last of the season around April 4. Those are the middle dates across the winters of 1991–2020 at Glendive, MT, 0.5 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 29 days after the last snow.
Planting calendar for 59330
| When | What to do |
|---|---|
| February 22 – March 8 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 8 – March 22 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 5 – April 19 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 3 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 12 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 20 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 4 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 59330 is under a mile from Glendive, MT, which stands at 2,075 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 59330 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.