USDA Hardiness Zone 5b
Frost Dates for 50313 — Des Moines, Iowa
NOAA 1991–2020 normals from Ankeny, IA (975 ft), 7 miles north.
Updated
In Des Moines, the last spring frost (32°F) is around April 23 in half of years and has passed by May 6 in nine years out of ten. The first fall frost comes around October 15, as early as September 30 one year in ten, leaving a typical freeze-free season of 173 days (NOAA, Ankeny, IA).
- Last spring frost
- April 23
- First fall frost
- October 15
- Growing season
- 173 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
- December 2
- Last snow
- March 17
- Winters with snow
- 100%
- Snow per year
- 24.7"
median, 1991–2020
median, 1991–2020
28 of 28 observed
NOAA normal
Frost risk by date in Des Moines
Half of springs at Ankeny, IA see their last 32°F night by April 23; only one in ten is past it by April 8, and one in ten still has one after May 6. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 2 20%, and after May 6 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 15 in half of years, as early as September 30 one year in ten, and holds off past October 28 one year in ten. A hard freeze of 28°F follows 10 days later, around October 25; in spring the one-in-ten date for 28°F is April 27, 9 days before the 32°F one. The freeze-free season lasts 173 days in a typical year, longer than at 76% of the 132 Iowa stations; it reaches 193 days one year in ten and falls short of 154 one year in ten. On average 150 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 3, and return around October 4. Severe cold of 16°F or below comes every winter, usually between November 22 and March 12.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 19 | Apr 24 | Apr 27 | Apr 30 | May 3 | May 5 | May 7 | May 11 | May 16 |
| 32°F | Apr 8 | Apr 13 | Apr 16 | Apr 19 | Apr 23 | Apr 25 | Apr 29 | May 2 | May 6 |
| 28°F | Mar 31 | Apr 3 | Apr 7 | Apr 10 | Apr 13 | Apr 15 | Apr 19 | Apr 23 | Apr 27 |
| 24°F | Mar 17 | Mar 23 | Mar 28 | Mar 31 | Apr 3 | Apr 6 | Apr 9 | Apr 13 | Apr 19 |
| 20°F | Mar 6 | Mar 11 | Mar 16 | Mar 20 | Mar 23 | Mar 27 | Mar 30 | Apr 2 | Apr 9 |
| 16°F | Feb 28 | Mar 3 | Mar 6 | Mar 9 | Mar 12 | Mar 15 | Mar 19 | Mar 23 | Mar 30 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 21 | Sep 26 | Sep 29 | Oct 2 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 18 |
| 32°F | Sep 30 | Oct 5 | Oct 9 | Oct 12 | Oct 15 | Oct 18 | Oct 20 | Oct 23 | Oct 28 |
| 28°F | Oct 11 | Oct 17 | Oct 20 | Oct 23 | Oct 25 | Oct 27 | Oct 29 | Nov 1 | Nov 5 |
| 24°F | Oct 20 | Oct 24 | Oct 28 | Oct 31 | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 17 |
| 20°F | Oct 30 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 15 | Nov 19 | Nov 23 | Nov 29 |
| 16°F | Nov 5 | Nov 10 | Nov 15 | Nov 18 | Nov 22 | Nov 25 | Nov 29 | Dec 3 | Dec 8 |
Freeze probabilities 1991–2020 at Ankeny, 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 50313 →Compare Des Moines with another place →
Weather by month in Des Moines
July is the warmest month at Ankeny, IA, averaging 86°F by day and 65°F at night; January is the coldest at 30°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 24% of years.
Warmth for growing adds up to 3,262 growing degree days a year (base 50°F), more than at 80% of the 132 Iowa stations. 35% of them (1,140) have built up by the end of June, and July adds the most, 781. Precipitation totals 37.2 inches a year, most in June (5.4") and least in January (1.0"); May to September bring 62% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 30 | 12 | 1.0 | 100% | 30 | 0 |
| Feb | 34 | 16 | 1.0 | 100% | 27 | 2 |
| Mar | 47 | 27 | 2.0 | 100% | 24 | 29 |
| Apr | 61 | 38 | 4.0 | 98% | 10 | 114 |
| May | 72 | 50 | 5.3 | 24% | 1 | 357 |
| Jun | 82 | 61 | 5.4 | 0% | 0 | 639 |
| Jul | 86 | 65 | 4.2 | 0% | 0 | 781 |
| Aug | 84 | 62 | 4.7 | 0% | 0 | 704 |
| Sep | 77 | 53 | 3.6 | 11% | 1 | 454 |
| Oct | 64 | 41 | 2.7 | 94% | 8 | 159 |
| Nov | 48 | 29 | 1.9 | 100% | 21 | 23 |
| Dec | 35 | 18 | 1.4 | 100% | 29 | 1 |
Monthly normals 1991–2020 at Ankeny, IA (975 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 International Airport, IA, 7 miles south of Des Moines, has a last frost 5 days earlier (April 18), a first frost 5 days later (October 20), a season 11 days longer.
When it snows in Des Moines, Iowa
The first measurable snow (0.1 inch or more) in Des Moines usually arrives around December 2, and the last of the season around March 17. Those are the middle dates across the winters of 1991–2020 at Ankeny, IA, 6.8 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 50313
| When | What to do |
|---|---|
| February 12 – February 26 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 26 – March 12 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 26 – April 9 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 23 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 23 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 1 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 15 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 50313 is 7 miles from Ankeny, IA, which stands at 975 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 50023 (Ankeny). The 2023 USDA Plant Hardiness Zone Map lists ZIP 50313 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.