USDA Hardiness Zone 5a
Frost Dates for 53572 — Mount Horeb, Wisconsin
NOAA 1991–2020 normals from Mazomanie Wwtp, WI (764 ft), 14 miles north.
Updated
In Mount Horeb, the last spring frost (32°F) is around May 7 in half of years and has passed by May 22 in nine years out of ten. The first fall frost comes around October 1, as early as September 18 one year in ten, leaving a typical freeze-free season of 148 days (NOAA, Mazomanie Wwtp, WI).
- Last spring frost
- May 7
- First fall frost
- October 1
- Growing season
- 148 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
- December 2
- Last snow
- March 21
- Winters with snow
- 100%
- Snow per year
- 30"
median, 1991–2020
median, 1991–2020
18 of 18 observed
NOAA normal
Frost risk by date in Mount Horeb
Half of springs at Mazomanie Wwtp, WI see their last 32°F night by May 7; only one in ten is past it by April 22, and one in ten still has one after May 22. Planting tender crops after May 13 leaves a 30% risk of a frost on them, after May 17 20%, and after May 22 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 30% of the 182 Wisconsin stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 1 in half of years, as early as September 18 one year in ten, and holds off past October 16 one year in ten. A hard freeze of 28°F follows 11 days later, around October 12; in spring the one-in-ten date for 28°F is May 13, 9 days before the 32°F one. The freeze-free season lasts 148 days in a typical year, shorter than at 69% of the 182 Wisconsin stations; it reaches 168 days one year in ten and falls short of 128 one year in ten. On average 156 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 11 days longer, to about May 18, and return around September 23. Severe cold of 16°F or below comes every winter, usually between November 17 and March 26.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 30 | May 6 | May 11 | May 14 | May 18 | May 21 | May 24 | May 28 | Jun 1 |
| 32°F | Apr 22 | Apr 27 | Apr 30 | May 4 | May 7 | May 10 | May 13 | May 17 | May 22 |
| 28°F | Apr 12 | Apr 16 | Apr 20 | Apr 24 | Apr 27 | Apr 30 | May 3 | May 7 | May 13 |
| 24°F | Apr 2 | Apr 6 | Apr 10 | Apr 13 | Apr 16 | Apr 20 | Apr 23 | Apr 28 | May 3 |
| 20°F | Mar 20 | Mar 26 | Mar 31 | Apr 2 | Apr 5 | Apr 7 | Apr 10 | Apr 15 | Apr 22 |
| 16°F | Mar 10 | Mar 15 | Mar 19 | Mar 23 | Mar 26 | Mar 30 | Apr 1 | Apr 4 | Apr 9 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 11 | Sep 15 | Sep 18 | Sep 21 | Sep 23 | Sep 26 | Sep 29 | Oct 1 | Oct 6 |
| 32°F | Sep 18 | Sep 23 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 16 |
| 28°F | Sep 26 | Oct 1 | Oct 4 | Oct 8 | Oct 12 | Oct 15 | Oct 18 | Oct 22 | Oct 29 |
| 24°F | Oct 7 | Oct 14 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 3 | Nov 8 |
| 20°F | Oct 21 | Oct 27 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 12 | Nov 16 | Nov 20 |
| 16°F | Nov 2 | Nov 7 | Nov 11 | Nov 15 | Nov 17 | Nov 20 | Nov 23 | Nov 27 | Dec 1 |
Freeze probabilities 1991–2020 at Mazomanie Wwtp, WI, 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 53572 →Compare Mount Horeb with another place →
Weather by month in Mount Horeb
July is the warmest month at Mazomanie Wwtp, WI, averaging 82°F by day and 58°F at night; January is the coldest at 28°F and 7°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 67% of years.
Warmth for growing adds up to 2,486 growing degree days a year (base 50°F), more than at 57% of the 182 Wisconsin stations. 34% of them (842) have built up by the end of June, and July adds the most, 618. Precipitation totals 35.7 inches a year, most in June (5.6") and least in February (1.3"); May to September bring 56% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 28 | 7 | 1.5 | 100% | 30 | 0 |
| Feb | 33 | 10 | 1.3 | 100% | 27 | 0 |
| Mar | 44 | 22 | 2.3 | 100% | 25 | 15 |
| Apr | 58 | 33 | 3.8 | 100% | 13 | 58 |
| May | 70 | 45 | 4.4 | 67% | 2 | 266 |
| Jun | 79 | 55 | 5.6 | 1% | <1 | 503 |
| Jul | 82 | 58 | 3.9 | 0% | 0 | 618 |
| Aug | 81 | 57 | 3.3 | 0% | 0 | 584 |
| Sep | 74 | 47 | 2.8 | 46% | 1 | 332 |
| Oct | 61 | 37 | 2.9 | 99% | 10 | 99 |
| Nov | 46 | 26 | 2.3 | 100% | 19 | 11 |
| Dec | 34 | 14 | 1.6 | 100% | 28 | 0 |
Monthly normals 1991–2020 at Mazomanie Wwtp, WI (764 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, Charmany Farm, WI, 14 miles east of Mount Horeb and 282 feet higher, has a last frost 9 days earlier (April 28), a first frost 14 days later (October 15), a season 21 days longer.
When it snows in Mount Horeb, Wisconsin
The first measurable snow (0.1 inch or more) in Mount Horeb usually arrives around December 2, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Mazomanie Wwtp, WI, 13.5 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 47 days after the last snow.
Planting calendar for 53572
| When | What to do |
|---|---|
| February 26 – March 12 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 12 – March 26 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 9 – April 23 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 7 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 9 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 17 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 1 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 53572 is 14 miles from Mazomanie Wwtp, WI, which stands at 764 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 53572 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.
Frost dates across Wisconsin →
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.