USDA Hardiness Zone 5a
Frost Dates for 50665 — Parkersburg, Iowa
NOAA 1991–2020 normals from Allison, IA (1,038 ft), 12 miles north.
Updated
In Parkersburg, the last spring frost (32°F) is around April 27 in half of years and has passed by May 8 in nine years out of ten. The first fall frost comes around October 8, as early as September 24 one year in ten, leaving a typical freeze-free season of 165 days (NOAA, Allison, IA).
- Last spring frost
- April 27
- First fall frost
- October 8
- 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 15
- Last snow
- April 5
- Winters with snow
- 100%
- Snow per year
- 31.6"
median, 1991–2020
median, 1991–2020
20 of 20 observed
NOAA normal
Frost risk by date in Parkersburg
Half of springs at Allison, IA see their last 32°F night by April 27; 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 11 days between the even-odds date and the one-in-ten date is narrower than at 88% of the 132 Iowa stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 8 in half of years, as early as September 24 one year in ten, and holds off past October 22 one year in ten. A hard freeze of 28°F follows 12 days later, around October 20; 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 165 days in a typical year, shorter than at 45% of the 132 Iowa stations; it reaches 186 days one year in ten and falls short of 146 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 8 days longer, to about May 5, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 14 and March 21.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 23 | Apr 28 | May 1 | May 3 | May 5 | May 7 | May 9 | May 12 | May 16 |
| 32°F | Apr 12 | Apr 17 | Apr 21 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 5 | May 8 |
| 28°F | Apr 2 | Apr 7 | Apr 10 | Apr 13 | Apr 16 | Apr 19 | Apr 22 | Apr 26 | Apr 30 |
| 24°F | Mar 22 | Mar 28 | Apr 1 | Apr 4 | Apr 6 | Apr 9 | Apr 12 | Apr 16 | Apr 22 |
| 20°F | Mar 13 | Mar 19 | Mar 23 | Mar 26 | Mar 30 | Apr 1 | Apr 4 | Apr 8 | Apr 14 |
| 16°F | Mar 6 | Mar 10 | Mar 14 | Mar 17 | Mar 21 | Mar 24 | Mar 28 | Mar 31 | Apr 6 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 17 | Sep 21 | Sep 24 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 12 |
| 32°F | Sep 24 | Sep 29 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 18 | Oct 22 |
| 28°F | Oct 4 | Oct 9 | Oct 13 | Oct 17 | Oct 20 | Oct 21 | Oct 24 | Oct 28 | Nov 1 |
| 24°F | Oct 15 | Oct 20 | Oct 22 | Oct 26 | Oct 29 | Oct 31 | Nov 3 | Nov 6 | Nov 10 |
| 20°F | Oct 25 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 21 |
| 16°F | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 14 | Nov 17 | Nov 21 | Nov 24 | Nov 29 |
Freeze probabilities 1991–2020 at Allison, 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 50665 →Compare Parkersburg with another place →
Weather by month in Parkersburg
July is the warmest month at Allison, IA, averaging 83°F by day and 63°F at night; January is the coldest at 25°F and 8°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 37% of years.
Warmth for growing adds up to 2,854 growing degree days a year (base 50°F), fewer than at 69% of the 132 Iowa stations. 35% of them (993) have built up by the end of June, and July adds the most, 705. Precipitation totals 35.4 inches a year, most in June (5.5") and least in January (0.9"); May to September bring 63% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 25 | 8 | 0.9 | 100% | 31 | 0 |
| Feb | 29 | 12 | 1.0 | 100% | 27 | 0 |
| Mar | 43 | 24 | 1.8 | 100% | 23 | 15 |
| Apr | 59 | 36 | 3.8 | 99% | 10 | 81 |
| May | 70 | 49 | 5.1 | 37% | 1 | 310 |
| Jun | 80 | 59 | 5.5 | 0% | 0 | 586 |
| Jul | 83 | 63 | 4.2 | 0% | 0 | 705 |
| Aug | 80 | 60 | 4.0 | 0% | 0 | 629 |
| Sep | 74 | 51 | 3.4 | 24% | <1 | 389 |
| Oct | 61 | 39 | 2.5 | 98% | 8 | 124 |
| Nov | 44 | 25 | 1.8 | 100% | 22 | 13 |
| Dec | 31 | 15 | 1.4 | 100% | 30 | 0 |
Monthly normals 1991–2020 at Allison, IA (1,038 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, 15 miles south of Parkersburg, has a last frost 2 days later (April 29), a first frost 1 day later (October 9), a season 5 days shorter.
When it snows in Parkersburg, Iowa
The first measurable snow (0.1 inch or more) in Parkersburg usually arrives around November 15, and the last of the season around April 5. Those are the middle dates across the winters of 1991–2020 at Parkersburg, IA, 1.2 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 22 days after the last snow.
Planting calendar for 50665
| 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 16 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 24 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 8 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 50665 is 12 miles from Allison, IA, which stands at 1,038 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 50665 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.