USDA Hardiness Zone 5a
Frost Dates for 50613 — Cedar Falls, Iowa
NOAA 1991–2020 normals from Waterloo Municipal Airport, IA (868 ft), 3 miles northeast.
Updated
In Cedar Falls, the last spring frost (32°F) is around April 27 in half of years and has passed by May 10 in nine years out of ten. The first fall frost comes around October 10, as early as September 26 one year in ten, leaving a typical freeze-free season of 165 days (NOAA, Waterloo Municipal Airport, IA).
- Last spring frost
- April 27
- First fall frost
- October 10
- Growing season
- 165 days
- Hardiness zone
- 5a
50% probability
50% probability
freeze-free, 50%
-20 to -15°F (-28.9 to -26.1°C) coldest night
- First snow
- November 12
- Last snow
- April 6
- Winters with snow
- 100%
- Snow per year
- 39.1"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Cedar Falls
Half of springs at Waterloo Municipal Airport, IA see their last 32°F night by April 27; only one in ten is past it by April 11, and one in ten still has one after May 10. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 5 20%, and after May 10 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 26 one year in ten, and holds off past October 21 one year in ten. A hard freeze of 28°F follows 10 days later, around October 20; in spring the one-in-ten date for 28°F is May 2, 8 days before the 32°F one. The freeze-free season lasts 165 days in a typical year, shorter than at 45% of the 132 Iowa stations; it reaches 184 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 9 days longer, to about May 6, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 17 and March 18.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 23 | Apr 28 | Apr 30 | May 3 | May 6 | May 8 | May 10 | May 14 | May 17 |
| 32°F | Apr 11 | Apr 16 | Apr 20 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 5 | May 10 |
| 28°F | Apr 3 | Apr 7 | Apr 10 | Apr 13 | Apr 16 | Apr 19 | Apr 22 | Apr 27 | May 2 |
| 24°F | Mar 22 | Mar 29 | Apr 1 | Apr 4 | Apr 7 | Apr 9 | Apr 13 | Apr 17 | Apr 22 |
| 20°F | Mar 11 | Mar 16 | Mar 21 | Mar 25 | Mar 29 | Apr 1 | Apr 3 | Apr 8 | Apr 14 |
| 16°F | Mar 2 | Mar 8 | Mar 12 | Mar 15 | Mar 18 | Mar 21 | Mar 26 | Mar 30 | Apr 3 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 16 | Sep 20 | Sep 24 | Sep 27 | Sep 30 | Oct 2 | Oct 4 | Oct 7 | Oct 11 |
| 32°F | Sep 26 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 12 | Oct 15 | Oct 18 | Oct 21 |
| 28°F | Oct 6 | Oct 11 | Oct 15 | Oct 18 | Oct 20 | Oct 22 | Oct 24 | Oct 27 | Oct 31 |
| 24°F | Oct 17 | Oct 21 | Oct 24 | Oct 27 | Oct 29 | Oct 31 | Nov 2 | Nov 5 | Nov 10 |
| 20°F | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 7 | Nov 9 | Nov 14 | Nov 18 | Nov 23 |
| 16°F | Nov 2 | Nov 6 | Nov 10 | Nov 13 | Nov 17 | Nov 19 | Nov 23 | Nov 26 | Dec 1 |
Freeze probabilities 1991–2020 at Waterloo Municipal Airport, 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 50613 →Compare Cedar Falls with another place →
Weather by month in Cedar Falls
July is the warmest month at Waterloo Municipal Airport, IA, averaging 85°F by day and 64°F at night; January is the coldest at 28°F and 11°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 36% of years.
Warmth for growing adds up to 3,194 growing degree days a year (base 50°F), more than at 72% of the 132 Iowa stations. 36% of them (1,142) have built up by the end of June, and July adds the most, 759. Precipitation totals 36.2 inches a year, most in June (5.7") and least in January (1.1"); May to September bring 60% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 28 | 11 | 1.1 | 100% | 30 | 0 |
| Feb | 33 | 15 | 1.1 | 100% | 26 | 1 |
| Mar | 47 | 27 | 2.0 | 100% | 23 | 24 |
| Apr | 61 | 38 | 4.0 | 99% | 10 | 107 |
| May | 73 | 50 | 4.6 | 36% | 1 | 366 |
| Jun | 82 | 61 | 5.7 | 0% | 0 | 645 |
| Jul | 85 | 64 | 4.3 | 0% | 0 | 759 |
| Aug | 83 | 61 | 4.2 | 0% | 0 | 680 |
| Sep | 77 | 52 | 3.1 | 19% | 1 | 442 |
| Oct | 63 | 40 | 2.8 | 99% | 9 | 149 |
| Nov | 47 | 28 | 1.9 | 100% | 22 | 20 |
| Dec | 34 | 17 | 1.4 | 100% | 29 | 1 |
Monthly normals 1991–2020 at Waterloo Municipal Airport, IA (868 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, Grundy Ctr, IA, 19 miles southwest of Cedar Falls, has a last frost 2 days later (April 29), a first frost 1 day earlier (October 9), a season 5 days shorter.
When it snows in Cedar Falls, Iowa
The first measurable snow (0.1 inch or more) in Cedar Falls usually arrives around November 12, and the last of the season around April 6. Those are the middle dates across the winters of 1991–2020 at Waterloo Municipal Airport, IA, 3.4 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 50613
| When | What to do |
|---|---|
| February 16 – March 2 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 2 – March 16 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 30 – April 13 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 27 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 50613 is 3 miles from Waterloo Municipal Airport, IA, which stands at 868 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 50613 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°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.