USDA Hardiness Zone 5b
Frost Dates for 69033 — Imperial, Nebraska
NOAA 1991–2020 normals from Imperial, NE (3,294 ft), 2 miles southeast.
Updated
In Imperial, the last spring frost (32°F) is around May 7 in half of years and has passed by May 18 in nine years out of ten. The first fall frost comes around October 5, as early as September 24 one year in ten, leaving a typical freeze-free season of 150 days (NOAA, Imperial, NE).
- Last spring frost
- May 7
- First fall frost
- October 5
- Growing season
- 150 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 3
- Last snow
- April 14
- Winters with snow
- 100%
- Snow per year
- 26"
median, 1991–2020
median, 1991–2020
28 of 28 observed
NOAA normal
Frost risk by date in Imperial
Half of springs at Imperial, NE see their last 32°F night by May 7; only one in ten is past it by April 27, and one in ten still has one after May 18. Planting tender crops after May 11 leaves a 30% risk of a frost on them, after May 14 20%, and after May 18 10%. The 11 days between the even-odds date and the one-in-ten date is narrower than at 84% of the 68 Nebraska stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 5 in half of years, as early as September 24 one year in ten, and holds off past October 15 one year in ten. A hard freeze of 28°F follows 8 days later, around October 13; in spring the one-in-ten date for 28°F is May 9, 9 days before the 32°F one. The freeze-free season lasts 150 days in a typical year, shorter than at 87% of the 68 Nebraska stations; it reaches 165 days one year in ten and falls short of 133 one year in ten. On average 170 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 8 days longer, to about May 15, and return around September 26. Severe cold of 16°F or below comes every winter, usually between November 6 and March 31.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 5 | May 8 | May 11 | May 13 | May 15 | May 17 | May 21 | May 24 | May 29 |
| 32°F | Apr 27 | May 1 | May 3 | May 5 | May 7 | May 9 | May 11 | May 14 | May 18 |
| 28°F | Apr 16 | Apr 20 | Apr 24 | Apr 26 | Apr 29 | May 1 | May 3 | May 5 | May 9 |
| 24°F | Apr 3 | Apr 9 | Apr 14 | Apr 16 | Apr 19 | Apr 22 | Apr 25 | Apr 28 | May 1 |
| 20°F | Mar 23 | Mar 28 | Apr 1 | Apr 4 | Apr 7 | Apr 11 | Apr 14 | Apr 18 | Apr 23 |
| 16°F | Mar 10 | Mar 16 | Mar 22 | Mar 26 | Mar 31 | Apr 2 | Apr 5 | Apr 9 | Apr 15 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 14 | Sep 18 | Sep 22 | Sep 24 | Sep 26 | Sep 28 | Oct 1 | Oct 3 | Oct 6 |
| 32°F | Sep 24 | Sep 28 | Oct 1 | Oct 3 | Oct 5 | Oct 7 | Oct 9 | Oct 12 | Oct 15 |
| 28°F | Oct 1 | Oct 5 | Oct 8 | Oct 11 | Oct 13 | Oct 15 | Oct 18 | Oct 20 | Oct 23 |
| 24°F | Oct 10 | Oct 14 | Oct 17 | Oct 19 | Oct 22 | Oct 24 | Oct 26 | Oct 28 | Nov 1 |
| 20°F | Oct 16 | Oct 20 | Oct 24 | Oct 26 | Oct 29 | Oct 31 | Nov 3 | Nov 6 | Nov 11 |
| 16°F | Oct 22 | Oct 27 | Oct 31 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 21 |
Freeze probabilities 1991–2020 at Imperial, 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 69033 →Compare Imperial with another place →
Weather by month in Imperial
July is the warmest month at Imperial, NE, averaging 91°F by day and 60°F at night; January is the coldest at 42°F and 12°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 81% of years.
Warmth for growing adds up to 3,064 growing degree days a year (base 50°F), fewer than at 71% of the 68 Nebraska stations. 32% of them (990) have built up by the end of June, and July adds the most, 789. Precipitation totals 19.9 inches a year, most in June (3.3") and least in January (0.4"); May to September bring 67% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 42 | 12 | 0.4 | 100% | 31 | 0 |
| Feb | 45 | 15 | 0.6 | 100% | 27 | 3 |
| Mar | 56 | 23 | 1.1 | 100% | 25 | 23 |
| Apr | 64 | 31 | 2.0 | 100% | 15 | 80 |
| May | 73 | 44 | 3.2 | 81% | 2 | 293 |
| Jun | 85 | 55 | 3.3 | 0% | 0 | 592 |
| Jul | 91 | 60 | 2.9 | 0% | 0 | 789 |
| Aug | 89 | 58 | 2.5 | 0% | 0 | 713 |
| Sep | 81 | 48 | 1.4 | 30% | 1 | 434 |
| Oct | 67 | 33 | 1.6 | 100% | 12 | 125 |
| Nov | 54 | 22 | 0.5 | 100% | 27 | 13 |
| Dec | 43 | 14 | 0.4 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Imperial, NE (3,294 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, Holyoke, CO, 35 miles west of Imperial and 486 feet higher, has a last frost 4 days later (May 11), a first frost 2 days earlier (October 3), a season 6 days shorter.
When it snows in Imperial, Nebraska
The first measurable snow (0.1 inch or more) in Imperial usually arrives around November 3, and the last of the season around April 14. Those are the middle dates across the winters of 1991–2020 at Imperial, NE, 1.9 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 23 days after the last snow.
Planting calendar for 69033
| When | What to do |
|---|---|
| February 26 – March 12 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 12 – March 26 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 9 – April 23 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 7 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 13 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 21 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 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 69033 is 2 miles from Imperial, NE, which stands at 3,294 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 69033 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.