USDA Hardiness Zone 4a
Frost Dates for 54558 — Saint Germain, Wisconsin
NOAA 1991–2020 normals from St Germain, WI (1,643 ft), under a mile north.
Updated
In Saint Germain, the last spring frost (32°F) is around May 19 in half of years and has passed by May 31 in nine years out of ten. The first fall frost comes around October 3, as early as September 18 one year in ten, leaving a typical freeze-free season of 136 days (NOAA, St Germain, WI).
- Last spring frost
- May 19
- First fall frost
- October 3
- Growing season
- 136 days
- Hardiness zone
- 4a
50% probability
50% probability
freeze-free, 50%
-30 to -25°F (-34.4 to -31.7°C) coldest night
- First snow
- October 31
- Last snow
- April 18
- Winters with snow
- 100%
- Snow per year
- 73.7"
median, 1991–2020
median, 1991–2020
28 of 28 observed
NOAA normal
Frost risk by date in Saint Germain
Half of springs at St Germain, WI see their last 32°F night by May 19; only one in ten is past it by May 5, and one in ten still has one after May 31. Planting tender crops after May 24 leaves a 30% risk of a frost on them, after May 26 20%, and after May 31 10%. The 12 days between the even-odds date and the one-in-ten date is the narrowest of the 182 Wisconsin stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 3 in half of years, as early as September 18 one year in ten, and holds off past October 13 one year in ten. A hard freeze of 28°F follows 9 days later, around October 12; in spring the one-in-ten date for 28°F is May 22, 9 days before the 32°F one. The freeze-free season lasts 136 days in a typical year, shorter than at 89% of the 182 Wisconsin stations; it reaches 153 days one year in ten and falls short of 118 one year in ten. On average 191 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 10 days longer, to about May 29, and return around September 23. Severe cold of 16°F or below comes every winter, usually between November 13 and April 10.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 16 | May 21 | May 24 | May 26 | May 29 | May 31 | Jun 2 | Jun 5 | Jun 9 |
| 32°F | May 5 | May 9 | May 13 | May 16 | May 19 | May 21 | May 24 | May 26 | May 31 |
| 28°F | Apr 26 | Apr 30 | May 3 | May 6 | May 8 | May 11 | May 14 | May 17 | May 22 |
| 24°F | Apr 15 | Apr 19 | Apr 23 | Apr 27 | Apr 29 | May 1 | May 4 | May 8 | May 13 |
| 20°F | Apr 4 | Apr 10 | Apr 13 | Apr 16 | Apr 18 | Apr 21 | Apr 24 | Apr 28 | May 1 |
| 16°F | Mar 29 | Apr 2 | Apr 4 | Apr 7 | Apr 10 | Apr 12 | Apr 16 | Apr 19 | Apr 23 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 7 | Sep 13 | Sep 17 | Sep 21 | Sep 23 | Sep 26 | Sep 29 | Oct 1 | Oct 5 |
| 32°F | Sep 18 | Sep 24 | Sep 27 | Oct 1 | Oct 3 | Oct 5 | Oct 7 | Oct 10 | Oct 13 |
| 28°F | Sep 30 | Oct 4 | Oct 7 | Oct 10 | Oct 12 | Oct 15 | Oct 17 | Oct 21 | Oct 25 |
| 24°F | Oct 10 | Oct 15 | Oct 19 | Oct 22 | Oct 25 | Oct 27 | Oct 31 | Nov 1 | Nov 6 |
| 20°F | Oct 23 | Oct 27 | Oct 30 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 17 |
| 16°F | Oct 31 | Nov 4 | Nov 7 | Nov 10 | Nov 13 | Nov 15 | Nov 18 | Nov 22 | Nov 26 |
Freeze probabilities 1991–2020 at St Germain, 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 54558 →Compare Saint Germain with another place →
Weather by month in Saint Germain
July is the warmest month at St Germain, WI, averaging 75°F by day and 56°F at night; January is the coldest at 20°F and 1°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month.
Warmth for growing adds up to 1,688 growing degree days a year (base 50°F), fewer than at 99% of the 182 Wisconsin stations. 30% of them (506) have built up by the end of June, and July adds the most, 491. Precipitation totals 33.6 inches a year, most in July (4.3") and least in February (1.2"); May to September bring 58% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 20 | 1 | 1.4 | 100% | 31 | 0 |
| Feb | 25 | 2 | 1.2 | 100% | 28 | 0 |
| Mar | 36 | 13 | 1.8 | 100% | 29 | 1 |
| Apr | 49 | 26 | 2.8 | 100% | 23 | 12 |
| May | 63 | 40 | 3.8 | 96% | 6 | 132 |
| Jun | 72 | 51 | 4.2 | 7% | <1 | 361 |
| Jul | 75 | 56 | 4.3 | 0% | 0 | 491 |
| Aug | 73 | 55 | 3.3 | 0% | 0 | 435 |
| Sep | 66 | 47 | 3.8 | 39% | 1 | 219 |
| Oct | 52 | 34 | 3.4 | 100% | 15 | 36 |
| Nov | 37 | 22 | 2.0 | 100% | 27 | 1 |
| Dec | 25 | 9 | 1.6 | 100% | 31 | 0 |
Monthly normals 1991–2020 at St Germain, WI (1,643 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, Eagle Rvr, WI, 11 miles east of Saint Germain, has a last frost 6 days later (May 25), a first frost 9 days earlier (September 24), a season 15 days shorter.
When it snows in Saint Germain, Wisconsin
The first measurable snow (0.1 inch or more) in Saint Germain usually arrives around October 31, and the last of the season around April 18. Those are the middle dates across the winters of 1991–2020 at St Germain, WI, 0.1 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 31 days after the last snow.
Planting calendar for 54558
| When | What to do |
|---|---|
| March 10 – March 24 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 24 – April 7 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 21 – May 5 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 19 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 11 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 19 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 3 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 54558 is under a mile from St Germain, WI, which stands at 1,643 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 54558 in zone 4a, the band where the coldest night of the year averaged -30 to -25°F (-34.4 to -31.7°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.