USDA Hardiness Zone 4b
Frost Dates for 58601 — Dickinson, North Dakota
NOAA 1991–2020 normals from Dickinson, ND (2,460 ft), 2 miles northeast.
Updated
In Dickinson, the last spring frost (32°F) is around May 20 in half of years and has passed by June 1 in nine years out of ten. The first fall frost comes around September 22, as early as September 8 one year in ten, leaving a typical freeze-free season of 123 days (NOAA, Dickinson, ND).
- Last spring frost
- May 20
- First fall frost
- September 22
- Growing season
- 123 days
- Hardiness zone
- 4b
50% probability
50% probability
freeze-free, 50%
-25 to -20°F (-31.7 to -28.9°C) coldest night
- First snow
- November 4
- Last snow
- April 14
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
22 of 22 observed
NOAA normal
Frost risk by date in Dickinson
Half of springs at Dickinson, ND see their last 32°F night by May 20; only one in ten is past it by May 8, and one in ten still has one after June 1. Planting tender crops after May 25 leaves a 30% risk of a frost on them, after May 28 20%, and after June 1 10%. The 12 days between the even-odds date and the one-in-ten date is narrower than at 79% of the 33 North Dakota stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 22 in half of years, as early as September 8 one year in ten, and holds off past October 3 one year in ten. A hard freeze of 28°F follows 7 days later, around September 29; in spring the one-in-ten date for 28°F is May 24, 8 days before the 32°F one. The freeze-free season lasts 123 days in a typical year, shorter than at 91% of the 33 North Dakota stations; it reaches 140 days one year in ten and falls short of 104 one year in ten. On average 201 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 31, and return around September 12. Severe cold of 16°F or below comes every winter, usually between October 25 and April 10.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 19 | May 24 | May 26 | May 28 | May 31 | Jun 2 | Jun 5 | Jun 10 | Jun 17 |
| 32°F | May 8 | May 12 | May 15 | May 17 | May 20 | May 23 | May 25 | May 28 | Jun 1 |
| 28°F | Apr 27 | May 2 | May 4 | May 7 | May 10 | May 12 | May 15 | May 19 | May 24 |
| 24°F | Apr 15 | Apr 20 | Apr 24 | Apr 28 | Apr 30 | May 2 | May 5 | May 9 | May 14 |
| 20°F | Apr 6 | Apr 10 | Apr 14 | Apr 16 | Apr 20 | Apr 23 | Apr 26 | Apr 29 | May 3 |
| 16°F | Mar 26 | Apr 1 | Apr 5 | Apr 8 | Apr 10 | Apr 13 | Apr 16 | Apr 20 | Apr 24 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 27 | Sep 2 | Sep 6 | Sep 9 | Sep 12 | Sep 15 | Sep 17 | Sep 20 | Sep 24 |
| 32°F | Sep 8 | Sep 13 | Sep 16 | Sep 19 | Sep 22 | Sep 24 | Sep 26 | Sep 29 | Oct 3 |
| 28°F | Sep 16 | Sep 20 | Sep 24 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 7 | Oct 13 |
| 24°F | Sep 23 | Sep 28 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 13 | Oct 16 | Oct 20 |
| 20°F | Oct 1 | Oct 5 | Oct 9 | Oct 13 | Oct 15 | Oct 18 | Oct 21 | Oct 25 | Oct 30 |
| 16°F | Oct 8 | Oct 14 | Oct 18 | Oct 22 | Oct 25 | Oct 27 | Oct 31 | Nov 3 | Nov 9 |
Freeze probabilities 1991–2020 at Dickinson, ND, 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 58601 →Compare Dickinson with another place →
Weather by month in Dickinson
July is the warmest month at Dickinson, ND, averaging 83°F by day and 55°F at night; January is the coldest at 27°F and 3°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 12% of years.
Warmth for growing adds up to 2,024 growing degree days a year (base 50°F), fewer than at 67% of the 33 North Dakota stations. 28% of them (567) have built up by the end of June, and July adds the most, 590. Precipitation totals 17.6 inches a year, most in June (3.2") and least in January (0.4"); May to September bring 69% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 27 | 3 | 0.4 | 100% | 31 | 0 |
| Feb | 31 | 7 | 0.5 | 100% | 28 | 0 |
| Mar | 41 | 17 | 0.7 | 100% | 30 | 2 |
| Apr | 54 | 28 | 1.6 | 100% | 20 | 30 |
| May | 66 | 40 | 2.6 | 98% | 7 | 158 |
| Jun | 75 | 50 | 3.2 | 12% | <1 | 377 |
| Jul | 83 | 55 | 2.7 | 0% | 0 | 590 |
| Aug | 83 | 53 | 1.9 | 2% | <1 | 556 |
| Sep | 73 | 43 | 1.7 | 83% | 4 | 261 |
| Oct | 57 | 29 | 1.3 | 100% | 21 | 47 |
| Nov | 42 | 17 | 0.6 | 100% | 29 | 3 |
| Dec | 30 | 7 | 0.4 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Dickinson, ND (2,460 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 Dickinson, North Dakota
The first measurable snow (0.1 inch or more) in Dickinson usually arrives around November 4, and the last of the season around April 14. Those are the middle dates across the winters of 1991–2020 at Dickinson, ND, 1.5 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 36 days after the last snow.
Planting calendar for 58601
| When | What to do |
|---|---|
| March 11 – March 25 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 25 – April 8 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 22 – May 6 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 20 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 30 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 8 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 22 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 58601 is 2 miles from Dickinson, ND, which stands at 2,460 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 58601 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across North Dakota →
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.