USDA Hardiness Zone 5b
Frost Dates for 52403 — Cedar Rapids, Iowa
NOAA 1991–2020 normals from Cedar Rapids #1, IA (813 ft), 5 miles north.
Updated
In Cedar Rapids, the last spring frost (32°F) is around April 28 in half of years and has passed by May 13 in nine years out of ten. The first fall frost comes around October 12, as early as September 29 one year in ten, leaving a typical freeze-free season of 166 days (NOAA, Cedar Rapids #1, IA).
- Last spring frost
- April 28
- First fall frost
- October 12
- 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 14
- Last snow
- March 31
- Winters with snow
- 100%
- Snow per year
- 34.3"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Cedar Rapids
Half of springs at Cedar Rapids #1, IA see their last 32°F night by April 28; only one in ten is past it by April 14, and one in ten still has one after May 13. Planting tender crops after May 4 leaves a 30% risk of a frost on them, after May 8 20%, and after May 13 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 82% of the 132 Iowa stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 12 in half of years, as early as September 29 one year in ten, and holds off past October 25 one year in ten. A hard freeze of 28°F follows 10 days later, around October 22; in spring the one-in-ten date for 28°F is May 2, 11 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 184 days one year in ten and falls short of 144 one year in ten. On average 134 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 9 days longer, to about May 7, and return around October 2. Severe cold of 16°F or below comes every winter, usually between November 19 and March 17.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 23 | Apr 28 | May 1 | May 4 | May 7 | May 10 | May 13 | May 17 | May 22 |
| 32°F | Apr 14 | Apr 18 | Apr 22 | Apr 25 | Apr 28 | May 1 | May 4 | May 8 | May 13 |
| 28°F | Apr 4 | Apr 8 | Apr 11 | Apr 14 | Apr 17 | Apr 20 | Apr 24 | Apr 28 | May 2 |
| 24°F | Mar 23 | Mar 30 | Apr 2 | Apr 4 | Apr 6 | Apr 8 | Apr 12 | Apr 17 | Apr 22 |
| 20°F | Mar 11 | Mar 17 | Mar 22 | Mar 26 | Mar 29 | Mar 31 | Apr 3 | Apr 5 | Apr 10 |
| 16°F | Mar 2 | Mar 7 | Mar 11 | Mar 14 | Mar 17 | Mar 20 | Mar 25 | Mar 29 | Apr 1 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 19 | Sep 24 | Sep 28 | Sep 30 | Oct 2 | Oct 5 | Oct 7 | Oct 10 | Oct 14 |
| 32°F | Sep 29 | Oct 3 | Oct 7 | Oct 9 | Oct 12 | Oct 15 | Oct 17 | Oct 20 | Oct 25 |
| 28°F | Oct 8 | Oct 14 | Oct 17 | Oct 20 | Oct 22 | Oct 24 | Oct 27 | Oct 29 | Nov 1 |
| 24°F | Oct 19 | Oct 23 | Oct 26 | Oct 28 | Oct 31 | Nov 2 | Nov 4 | Nov 7 | Nov 12 |
| 20°F | Oct 30 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 20 | Nov 25 |
| 16°F | Nov 4 | Nov 8 | Nov 12 | Nov 16 | Nov 19 | Nov 22 | Nov 26 | Dec 1 | Dec 6 |
Freeze probabilities 1991–2020 at Cedar Rapids #1, 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 52403 →Compare Cedar Rapids with another place →
Weather by month in Cedar Rapids
July is the warmest month at Cedar Rapids #1, IA, averaging 86°F by day and 63°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 August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 41% of years.
Warmth for growing adds up to 3,266 growing degree days a year (base 50°F), more than at 81% of the 132 Iowa stations. 36% of them (1,164) have built up by the end of June, and July adds the most, 756. Precipitation totals 38.8 inches a year, most in June (5.7") and least in January (1.2"); May to September bring 60% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 30 | 13 | 1.2 | 100% | 30 | 0 |
| Feb | 35 | 17 | 1.3 | 100% | 25 | 2 |
| Mar | 49 | 28 | 2.1 | 100% | 20 | 31 |
| Apr | 63 | 38 | 4.0 | 99% | 7 | 131 |
| May | 74 | 50 | 4.7 | 41% | 1 | 372 |
| Jun | 82 | 60 | 5.7 | 0% | 0 | 628 |
| Jul | 86 | 63 | 4.5 | 0% | 0 | 756 |
| Aug | 83 | 61 | 4.4 | 0% | 0 | 691 |
| Sep | 77 | 53 | 4.0 | 13% | <1 | 458 |
| Oct | 64 | 42 | 3.0 | 98% | 5 | 170 |
| Nov | 48 | 29 | 2.2 | 100% | 18 | 26 |
| Dec | 35 | 19 | 1.7 | 100% | 28 | 2 |
Monthly normals 1991–2020 at Cedar Rapids #1, IA (813 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, Cedar Rapids Municipal Airport, IA, 9 miles southwest of Cedar Rapids, has a last frost 1 day earlier (April 27), a first frost 1 day earlier (October 11), a season 1 day shorter.
When it snows in Cedar Rapids, Iowa
The first measurable snow (0.1 inch or more) in Cedar Rapids usually arrives around November 14, and the last of the season around March 31. Those are the middle dates across the winters of 1991–2020 at Cedar Rapids #1, IA, 4.9 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 28 days after the last snow.
Planting calendar for 52403
| When | What to do |
|---|---|
| February 17 – March 3 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 3 – March 17 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 31 – April 14 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 28 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 20 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 28 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 12 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 52403 is 5 miles from Cedar Rapids #1, IA, which stands at 813 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station; its figures are presented in full for 52402 (Cedar Rapids). The 2023 USDA Plant Hardiness Zone Map lists ZIP 52403 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.