USDA Hardiness Zone 4b
Frost Dates for 54401 — Wausau, Wisconsin
NOAA 1991–2020 normals from Wausau Dwtn Airport, WI (1,181 ft), 3 miles southeast.
Updated
In Wausau, the last spring frost (32°F) is around May 6 in half of years and has passed by May 21 in nine years out of ten. The first fall frost comes around October 4, as early as September 21 one year in ten, leaving a typical freeze-free season of 150 days (NOAA, Wausau Dwtn Airport, WI).
- Last spring frost
- May 6
- First fall frost
- October 4
- Growing season
- 150 days
- Hardiness zone
- 4b
50% probability
50% probability
freeze-free, 50%
-25 to -20°F (-31.7 to -28.9°C) coldest night
- First snow
- November 6
- Last snow
- April 17
- Winters with snow
- 100%
- Snow per year
- 64.3"
median, 1991–2020
median, 1991–2020
29 of 29 observed
NOAA normal
Frost risk by date in Wausau
Half of springs at Wausau Dwtn Airport, WI see their last 32°F night by May 6; only one in ten is past it by April 24, and one in ten still has one after May 21. Planting tender crops after May 12 leaves a 30% risk of a frost on them, after May 17 20%, and after May 21 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 4 in half of years, as early as September 21 one year in ten, and holds off past October 18 one year in ten. A hard freeze of 28°F follows 12 days later, around October 16; in spring the one-in-ten date for 28°F is May 10, 11 days before the 32°F one. The freeze-free season lasts 150 days in a typical year, shorter than at 64% of the 182 Wisconsin stations; it reaches 170 days one year in ten and falls short of 130 one year in ten. On average 163 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 13 days longer, to about May 19, and return around September 25. Severe cold of 16°F or below comes every winter, usually between November 17 and March 30.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 4 | May 8 | May 12 | May 16 | May 19 | May 21 | May 25 | May 27 | May 31 |
| 32°F | Apr 24 | Apr 28 | May 1 | May 4 | May 6 | May 8 | May 12 | May 17 | May 21 |
| 28°F | Apr 12 | Apr 16 | Apr 20 | Apr 23 | Apr 26 | Apr 29 | May 1 | May 5 | May 10 |
| 24°F | Apr 1 | Apr 5 | Apr 9 | Apr 12 | Apr 15 | Apr 18 | Apr 21 | Apr 24 | Apr 29 |
| 20°F | Mar 22 | Mar 27 | Mar 31 | Apr 2 | Apr 4 | Apr 8 | Apr 11 | Apr 15 | Apr 20 |
| 16°F | Mar 13 | Mar 19 | Mar 23 | Mar 27 | Mar 30 | Apr 1 | Apr 3 | Apr 6 | Apr 12 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 12 | Sep 17 | Sep 20 | Sep 23 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 7 |
| 32°F | Sep 21 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 12 | Oct 18 |
| 28°F | Oct 1 | Oct 5 | Oct 9 | Oct 13 | Oct 16 | Oct 19 | Oct 23 | Oct 26 | Oct 31 |
| 24°F | Oct 14 | Oct 20 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 7 | Nov 13 |
| 20°F | Oct 27 | Nov 1 | Nov 3 | Nov 5 | Nov 8 | Nov 11 | Nov 14 | Nov 17 | Nov 21 |
| 16°F | Nov 4 | Nov 8 | Nov 11 | Nov 14 | Nov 17 | Nov 20 | Nov 22 | Nov 26 | Nov 30 |
Freeze probabilities 1991–2020 at Wausau Dwtn Airport, 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 54401 →Compare Wausau with another place →
Weather by month in Wausau
July is the warmest month at Wausau Dwtn Airport, WI, averaging 80°F by day and 59°F at night; January is the coldest at 23°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 71% of years.
Warmth for growing adds up to 2,238 growing degree days a year (base 50°F), fewer than at 73% of the 182 Wisconsin stations. 33% of them (732) have built up by the end of June, and July adds the most, 604. Precipitation totals 34.0 inches a year, most in June (4.7") and least in February (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 | 23 | 7 | 1.2 | 100% | 31 | 0 |
| Feb | 27 | 10 | 1.1 | 100% | 27 | 0 |
| Mar | 40 | 21 | 1.8 | 100% | 26 | 8 |
| Apr | 54 | 32 | 3.1 | 100% | 15 | 41 |
| May | 67 | 45 | 3.8 | 71% | 2 | 222 |
| Jun | 76 | 55 | 4.7 | 0% | 0 | 461 |
| Jul | 80 | 59 | 3.9 | 0% | 0 | 604 |
| Aug | 78 | 57 | 4.1 | 0% | 0 | 539 |
| Sep | 70 | 49 | 3.8 | 35% | 1 | 293 |
| Oct | 56 | 37 | 3.1 | 99% | 9 | 66 |
| Nov | 40 | 25 | 1.9 | 100% | 23 | 5 |
| Dec | 28 | 14 | 1.5 | 100% | 30 | 0 |
Monthly normals 1991–2020 at Wausau Dwtn Airport, WI (1,181 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, Merrill, WI, 15 miles north of Wausau, has a last frost 5 days later (May 11), a first frost 4 days earlier (September 30), a season 11 days shorter.
When it snows in Wausau, Wisconsin
The first measurable snow (0.1 inch or more) in Wausau usually arrives around November 6, and the last of the season around April 17. Those are the middle dates across the winters of 1991–2020 at Wausau Dwtn Airport, WI, 3.1 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 19 days after the last snow.
Planting calendar for 54401
| When | What to do |
|---|---|
| February 25 – March 11 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 11 – March 25 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 8 – April 22 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 6 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 12 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 20 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 4 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 54401 is 3 miles from Wausau Dwtn Airport, WI, which stands at 1,181 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 54401 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°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.