USDA Hardiness Zone 7a
Frost Dates for 45638 — Ironton, Ohio
NOAA 1991–2020 normals from Ashland, KY (560 ft), 7 miles southeast.
Updated
In Ironton, the last spring frost (32°F) is around April 22 in half of years and has passed by May 11 in nine years out of ten. The first fall frost comes around October 23, as early as October 11 one year in ten, leaving a typical freeze-free season of 181 days (NOAA, Ashland, KY).
- Last spring frost
- April 22
- First fall frost
- October 23
- Growing season
- 181 days
- Hardiness zone
- 7a
50% probability
50% probability
freeze-free, 50%
0 to 5°F (-17.8 to -15.0°C) coldest night
- First snow
- December 31
- Last snow
- February 9
- Winters with snow
- 80%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
16 of 20 observed
NOAA normal
Frost risk by date in Ironton
Half of springs at Ashland, KY see their last 32°F night by April 22; only one in ten is past it by April 6, and one in ten still has one after May 11. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 5 20%, and after May 11 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 92% of the 148 Ohio stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 23 in half of years, as early as October 11 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 9 days later, around November 1; in spring the one-in-ten date for 28°F is May 1, 10 days before the 32°F one. The freeze-free season lasts 181 days in a typical year, longer than at 53% of the 148 Ohio stations; it reaches 202 days one year in ten and falls short of 160 one year in ten. On average 125 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 12 days longer, to about May 4, and return around October 14. Severe cold of 16°F or below comes every winter, usually between December 10 and March 3.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 18 | Apr 23 | Apr 27 | Apr 30 | May 4 | May 7 | May 10 | May 13 | May 18 |
| 32°F | Apr 6 | Apr 10 | Apr 14 | Apr 18 | Apr 22 | Apr 26 | Apr 30 | May 5 | May 11 |
| 28°F | Mar 24 | Mar 30 | Apr 2 | Apr 5 | Apr 8 | Apr 12 | Apr 17 | Apr 22 | May 1 |
| 24°F | Mar 9 | Mar 16 | Mar 20 | Mar 25 | Mar 28 | Mar 31 | Apr 2 | Apr 6 | Apr 13 |
| 20°F | Feb 24 | Mar 1 | Mar 7 | Mar 11 | Mar 15 | Mar 18 | Mar 22 | Mar 27 | Apr 1 |
| 16°F | Feb 6 | Feb 17 | Feb 24 | Feb 28 | Mar 3 | Mar 6 | Mar 11 | Mar 16 | Mar 21 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 1 | Oct 6 | Oct 9 | Oct 12 | Oct 14 | Oct 16 | Oct 19 | Oct 22 | Oct 26 |
| 32°F | Oct 11 | Oct 15 | Oct 18 | Oct 20 | Oct 23 | Oct 25 | Oct 28 | Oct 31 | Nov 3 |
| 28°F | Oct 19 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 14 |
| 24°F | Oct 30 | Nov 2 | Nov 6 | Nov 8 | Nov 11 | Nov 14 | Nov 18 | Nov 22 | Nov 27 |
| 20°F | Nov 8 | Nov 13 | Nov 17 | Nov 21 | Nov 25 | Nov 29 | Dec 3 | Dec 8 | Dec 18 |
| 16°F | Nov 19 | Nov 25 | Dec 1 | Dec 5 | Dec 10 | Dec 16 | Dec 21 | Dec 27 | Jan 2 |
Freeze probabilities 1991–2020 at Ashland, KY, 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 45638 →Compare Ironton with another place →
Weather by month in Ironton
July is the warmest month at Ashland, KY, averaging 85°F by day and 65°F at night; January is the coldest at 40°F and 23°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 29% of years.
Warmth for growing adds up to 3,564 growing degree days a year (base 50°F), more than at 81% of the 148 Ohio stations. 37% of them (1,308) have built up by the end of June, and July adds the most, 775. Precipitation totals 46.9 inches a year, most in May (4.9") and least in October (3.0"); May to September bring 45% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 40 | 23 | 3.5 | 100% | 27 | 6 |
| Feb | 44 | 24 | 3.7 | 100% | 24 | 8 |
| Mar | 54 | 32 | 4.4 | 100% | 19 | 49 |
| Apr | 67 | 41 | 3.9 | 96% | 8 | 189 |
| May | 75 | 51 | 4.9 | 29% | 1 | 410 |
| Jun | 83 | 61 | 4.5 | 0% | 0 | 647 |
| Jul | 85 | 65 | 4.6 | 0% | 0 | 775 |
| Aug | 84 | 63 | 3.9 | 0% | 0 | 730 |
| Sep | 78 | 56 | 3.3 | 0% | <1 | 508 |
| Oct | 67 | 43 | 3.0 | 81% | 5 | 195 |
| Nov | 54 | 32 | 3.0 | 100% | 17 | 39 |
| Dec | 44 | 27 | 4.2 | 100% | 25 | 10 |
Monthly normals 1991–2020 at Ashland, KY (560 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, S Pt, OH, 9 miles southeast of Ironton, has a last frost 6 days earlier (April 16), a first frost 7 days later (October 30), a season 15 days longer.
When it snows in Ironton, Ohio
The first measurable snow (0.1 inch or more) in Ironton usually arrives around December 31, and the last of the season around February 9. Those are the middle dates across the winters of 1991–2020 at Ashland, KY, 6.5 miles away: half of years saw snow earlier, half later. Snow fell in 80% of those winters. The last 32°F night of spring typically comes 72 days after the last snow.
Planting calendar for 45638
| When | What to do |
|---|---|
| February 11 – February 25 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 25 – March 11 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 25 – April 8 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 22 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 31 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 9 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 23 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 45638 is 7 miles from Ashland, KY, which stands at 560 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 41102 (Ashland). The 2023 USDA Plant Hardiness Zone Map lists ZIP 45638 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°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.