USDA Hardiness Zone 5b
Frost Dates for 50003 — Adel, Iowa
NOAA 1991–2020 normals from Perry, IA (950 ft), 16 miles north.
Updated
In Adel, the last spring frost (32°F) is around April 25 in half of years and has passed by May 8 in nine years out of ten. The first fall frost comes around October 10, as early as September 25 one year in ten, leaving a typical freeze-free season of 166 days (NOAA, Perry, IA).
- Last spring frost
- April 25
- First fall frost
- October 10
- Growing season
- 166 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 24
- Last snow
- March 19
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
26 of 26 observed
NOAA normal
Frost risk by date in Adel
Half of springs at Perry, IA see their last 32°F night by April 25; only one in ten is past it by April 12, and one in ten still has one after May 8. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 5 20%, and after May 8 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 42% of the 132 Iowa stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 10 in half of years, as early as September 25 one year in ten, and holds off past October 24 one year in ten. A hard freeze of 28°F follows 12 days later, around October 22; in spring the one-in-ten date for 28°F is April 30, 8 days before the 32°F one. The freeze-free season lasts 166 days in a typical year, longer than at 56% of the 132 Iowa stations; it reaches 185 days one year in ten and falls short of 146 one year in ten. On average 151 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 10 days longer, to about May 5, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 17 and March 16.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 22 | Apr 26 | Apr 30 | May 3 | May 5 | May 7 | May 9 | May 13 | May 17 |
| 32°F | Apr 12 | Apr 16 | Apr 19 | Apr 22 | Apr 25 | Apr 28 | May 2 | May 5 | May 8 |
| 28°F | Apr 2 | Apr 6 | Apr 10 | Apr 13 | Apr 16 | Apr 18 | Apr 22 | Apr 25 | Apr 30 |
| 24°F | Mar 21 | Mar 28 | Apr 1 | Apr 3 | Apr 6 | Apr 9 | Apr 12 | Apr 16 | Apr 21 |
| 20°F | Mar 10 | Mar 15 | Mar 20 | Mar 23 | Mar 27 | Mar 31 | Apr 2 | Apr 5 | Apr 12 |
| 16°F | Mar 1 | Mar 6 | Mar 10 | Mar 13 | Mar 16 | Mar 19 | Mar 23 | Mar 28 | Apr 2 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 17 | Sep 21 | Sep 25 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 9 | Oct 13 |
| 32°F | Sep 25 | Sep 30 | Oct 3 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 19 | Oct 24 |
| 28°F | Oct 5 | Oct 12 | Oct 15 | Oct 19 | Oct 22 | Oct 24 | Oct 27 | Oct 30 | Nov 3 |
| 24°F | Oct 19 | Oct 24 | Oct 27 | Oct 29 | Nov 1 | Nov 2 | Nov 5 | Nov 8 | Nov 13 |
| 20°F | Oct 28 | Nov 1 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 14 | Nov 18 | Nov 25 |
| 16°F | Nov 2 | Nov 7 | Nov 10 | Nov 14 | Nov 17 | Nov 20 | Nov 25 | Nov 30 | Dec 3 |
Freeze probabilities 1991–2020 at Perry, IA, 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 50003 →Compare Adel with another place →
Weather by month in Adel
July is the warmest month at Perry, IA, averaging 85°F by day and 64°F at night; January is the coldest at 30°F and 10°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 33% of years.
Warmth for growing adds up to 3,139 growing degree days a year (base 50°F), more than at 66% of the 132 Iowa stations. 35% of them (1,092) have built up by the end of June, and July adds the most, 758. Precipitation totals 36.2 inches a year, most in May (5.2") and least in January (1.0"); May to September bring 61% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 30 | 10 | 1.0 | 100% | 31 | 0 |
| Feb | 34 | 14 | 1.1 | 100% | 27 | 1 |
| Mar | 48 | 26 | 2.0 | 100% | 24 | 21 |
| Apr | 61 | 37 | 4.1 | 99% | 10 | 106 |
| May | 72 | 49 | 5.2 | 33% | 1 | 338 |
| Jun | 82 | 60 | 4.9 | 0% | 0 | 626 |
| Jul | 85 | 64 | 4.4 | 0% | 0 | 758 |
| Aug | 83 | 61 | 4.1 | 0% | 0 | 683 |
| Sep | 77 | 52 | 3.4 | 22% | 1 | 435 |
| Oct | 64 | 39 | 2.7 | 97% | 9 | 151 |
| Nov | 48 | 27 | 1.9 | 100% | 21 | 20 |
| Dec | 35 | 17 | 1.4 | 100% | 29 | 1 |
Monthly normals 1991–2020 at Perry, IA (950 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, Des Moines Wsfo-Johnston, IA, 18 miles northeast of Adel, has a last frost 6 days earlier (April 19), a first frost 8 days later (October 18), a season 13 days longer.
When it snows in Adel, Iowa
The first measurable snow (0.1 inch or more) in Adel usually arrives around November 24, and the last of the season around March 19. Those are the middle dates across the winters of 1991–2020 at Perry, IA, 16.1 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 37 days after the last snow.
Planting calendar for 50003
| When | What to do |
|---|---|
| February 14 – February 28 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 28 – March 14 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 28 – April 11 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 25 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 18 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 26 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 10 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 50003 is 16 miles from Perry, IA, which stands at 950 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 50003 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.