USDA Hardiness Zone 5b
Frost Dates for 68023 — Fort Calhoun, Nebraska
NOAA 1991–2020 normals from Fort Calhoun 4W, NE (1,310 ft), 4 miles west.
Updated
In Fort Calhoun, the last spring frost (32°F) is around April 19 in half of years and has passed by May 6 in nine years out of ten. The first fall frost comes around October 17, as early as October 1 one year in ten, leaving a typical freeze-free season of 180 days (NOAA, Fort Calhoun 4W, NE).
- Last spring frost
- April 19
- First fall frost
- October 17
- Growing season
- 180 days
- Hardiness zone
- 5b
50% probability
50% probability
freeze-free, 50%
-15 to -10°F (-26.1 to -23.3°C) coldest night
- First snow
- November 20
- Last snow
- March 29
- Winters with snow
- 100%
- Snow per year
- 34.4"
median, 1991–2020
median, 1991–2020
25 of 25 observed
NOAA normal
Frost risk by date in Fort Calhoun
Half of springs at Fort Calhoun 4W, NE see their last 32°F night by April 19; only one in ten is past it by April 5, and one in ten still has one after May 6. Planting tender crops after April 27 leaves a 30% risk of a frost on them, after April 30 20%, and after May 6 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 97% of the 68 Nebraska stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 17 in half of years, as early as October 1 one year in ten, and holds off past October 31 one year in ten. A hard freeze of 28°F follows 10 days later, around October 27; in spring the one-in-ten date for 28°F is April 24, 12 days before the 32°F one. The freeze-free season lasts 180 days in a typical year, longer than at 91% of the 68 Nebraska stations; it reaches 198 days one year in ten and falls short of 158 one year in ten. On average 140 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 12 days longer, to about May 1, and return around October 7. Severe cold of 16°F or below comes every winter, usually between November 20 and March 14.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 16 | Apr 21 | Apr 25 | Apr 29 | May 1 | May 3 | May 6 | May 9 | May 14 |
| 32°F | Apr 5 | Apr 10 | Apr 13 | Apr 16 | Apr 19 | Apr 23 | Apr 27 | Apr 30 | May 6 |
| 28°F | Mar 28 | Apr 1 | Apr 3 | Apr 6 | Apr 9 | Apr 11 | Apr 15 | Apr 19 | Apr 24 |
| 24°F | Mar 16 | Mar 23 | Mar 27 | Mar 31 | Apr 1 | Apr 4 | Apr 6 | Apr 10 | Apr 14 |
| 20°F | Mar 7 | Mar 12 | Mar 16 | Mar 20 | Mar 23 | Mar 27 | Mar 30 | Apr 2 | Apr 6 |
| 16°F | Mar 1 | Mar 4 | Mar 8 | Mar 11 | Mar 14 | Mar 18 | Mar 21 | Mar 25 | Mar 31 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 23 | Sep 28 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 20 |
| 32°F | Oct 1 | Oct 7 | Oct 11 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 31 |
| 28°F | Oct 12 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 5 | Nov 9 |
| 24°F | Oct 20 | Oct 25 | Oct 30 | Nov 1 | Nov 4 | Nov 7 | Nov 9 | Nov 13 | Nov 18 |
| 20°F | Oct 29 | Nov 2 | Nov 6 | Nov 8 | Nov 11 | Nov 14 | Nov 18 | Nov 22 | Nov 28 |
| 16°F | Nov 4 | Nov 9 | Nov 12 | Nov 16 | Nov 20 | Nov 23 | Nov 27 | Dec 1 | Dec 5 |
Freeze probabilities 1991–2020 at Fort Calhoun 4W, NE, 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 68023 →Compare Fort Calhoun with another place →
Weather by month in Fort Calhoun
July is the warmest month at Fort Calhoun 4W, NE, averaging 84°F by day and 65°F at night; January is the coldest at 30°F and 13°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 19% of years.
Warmth for growing adds up to 3,190 growing degree days a year (base 50°F), fewer than at 57% of the 68 Nebraska stations. 35% of them (1,112) have built up by the end of June, and July adds the most, 758.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 30 | 13 | 100% | 30 | 0 |
| Feb | 35 | 16 | 100% | 27 | 1 |
| Mar | 48 | 27 | 100% | 21 | 34 |
| Apr | 61 | 39 | 98% | 7 | 124 |
| May | 70 | 50 | 19% | <1 | 336 |
| Jun | 80 | 61 | 0% | 0 | 616 |
| Jul | 84 | 65 | 0% | 0 | 758 |
| Aug | 82 | 63 | 0% | 0 | 699 |
| Sep | 75 | 54 | 10% | 0 | 448 |
| Oct | 62 | 42 | 90% | 6 | 156 |
| Nov | 47 | 28 | 100% | 20 | 17 |
| Dec | 34 | 18 | 100% | 29 | 0 |
Monthly normals 1991–2020 at Fort Calhoun 4W, NE (1,310 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, Omaha #1, NE, 8 miles south of Fort Calhoun, has a last frost 3 days earlier (April 16), a first frost 1 day later (October 18), a season 3 days longer.
When it snows in Fort Calhoun, Nebraska
The first measurable snow (0.1 inch or more) in Fort Calhoun usually arrives around November 20, and the last of the season around March 29. Those are the middle dates across the winters of 1991–2020 at Bennington 3WSW, NE, 12.1 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 21 days after the last snow.
Planting calendar for 68023
| When | What to do |
|---|---|
| February 8 – February 22 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 22 – March 8 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 22 – April 5 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 19 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 25 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 3 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 17 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 68023 is 4 miles from Fort Calhoun 4W, NE, which stands at 1,310 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 68007 (Bennington). The 2023 USDA Plant Hardiness Zone Map lists ZIP 68023 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°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.