USDA Hardiness Zone 5b
Frost Dates for 53089 — Sussex, Wisconsin
NOAA 1991–2020 normals from Richfield 3 SSW, WI (984 ft), 5 miles north.
Updated
In Sussex, the last spring frost (32°F) is around April 30 in half of years and has passed by May 16 in nine years out of ten. The first fall frost comes around October 16, as early as October 1 one year in ten, leaving a typical freeze-free season of 167 days (NOAA, Richfield 3 SSW, WI).
- Last spring frost
- April 30
- First fall frost
- October 16
- Growing season
- 167 days
- Hardiness zone
- 5b
50% probability
50% probability
freeze-free, 50%
-15 to -10°F (-26.1 to -23.3°C) coldest night
- First snow
- November 17
- Last snow
- April 9
- Winters with snow
- 100%
- Snow per year
- 54.3"
median, 1991–2020
median, 1991–2020
29 of 29 observed
NOAA normal
Frost risk by date in Sussex
Half of springs at Richfield 3 SSW, WI see their last 32°F night by April 30; only one in ten is past it by April 16, and one in ten still has one after May 16. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 11 20%, and after May 16 10%. The 16 days between the even-odds date and the one-in-ten date is wider than at 70% of the 182 Wisconsin stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 16 in half of years, as early as October 1 one year in ten, and holds off past October 29 one year in ten. A hard freeze of 28°F follows 11 days later, around October 27; in spring the one-in-ten date for 28°F is May 4, 12 days before the 32°F one. The freeze-free season lasts 167 days in a typical year, longer than at 79% of the 182 Wisconsin stations; it reaches 187 days one year in ten and falls short of 147 one year in ten. On average 153 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 12, and return around October 4. Severe cold of 16°F or below comes every winter, usually between November 24 and March 18.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 28 | May 2 | May 6 | May 8 | May 12 | May 15 | May 19 | May 23 | May 28 |
| 32°F | Apr 16 | Apr 21 | Apr 24 | Apr 28 | Apr 30 | May 3 | May 6 | May 11 | May 16 |
| 28°F | Apr 5 | Apr 9 | Apr 13 | Apr 15 | Apr 19 | Apr 22 | Apr 26 | Apr 30 | May 4 |
| 24°F | Mar 23 | Mar 30 | Apr 1 | Apr 4 | Apr 6 | Apr 9 | Apr 12 | Apr 16 | Apr 21 |
| 20°F | Mar 13 | Mar 18 | Mar 21 | Mar 25 | Mar 29 | Mar 31 | Apr 2 | Apr 5 | Apr 10 |
| 16°F | Mar 5 | Mar 9 | Mar 13 | Mar 15 | Mar 18 | Mar 21 | Mar 25 | Mar 28 | Mar 31 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 22 | Sep 26 | Sep 30 | Oct 2 | Oct 4 | Oct 7 | Oct 9 | Oct 13 | Oct 17 |
| 32°F | Oct 1 | Oct 6 | Oct 10 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 29 |
| 28°F | Oct 11 | Oct 17 | Oct 22 | Oct 25 | Oct 27 | Oct 30 | Nov 1 | Nov 5 | Nov 10 |
| 24°F | Oct 26 | Oct 30 | Nov 1 | Nov 4 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 20 |
| 20°F | Nov 2 | Nov 6 | Nov 10 | Nov 13 | Nov 16 | Nov 18 | Nov 22 | Nov 25 | Nov 29 |
| 16°F | Nov 9 | Nov 14 | Nov 18 | Nov 21 | Nov 24 | Nov 26 | Nov 29 | Dec 3 | Dec 9 |
Freeze probabilities 1991–2020 at Richfield 3 SSW, 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 53089 →Compare Sussex with another place →
Frost risk through the year in Sussex
In Sussex, the spring curve drops under 10% on May 16 and the fall curve passes 10% on October 1, 138 days later; that gap is longer than at 77% of the 182 Wisconsin stations with frost dates. The spring risk falls from 90% to 10% over 30 days (April 16 to May 16) and the fall risk climbs from 10% to 90% over 28 days (October 1 to October 29): both ends of the season vary about as much. At Brookfield Wwtp, WI, 7 miles south, the same gap runs from May 15 to September 28, 2 days shorter.
| Planted on | Another 32°F night | 28°F night |
|---|---|---|
| Apr 16 | over 90% | 58% |
| Apr 23 | 73% | 38% |
| Apr 3050% date | 50% | 20% |
| May 7 | 28% | under 10% |
| May 14 | 14% | under 10% |
| May 21 | under 10% | under 10% |
Compared with the next station
The nearest other station, Brookfield Wwtp, WI, 7 miles south of Sussex and 154 feet lower, has the same 50% last-frost date, a first frost 2 days earlier (October 14), a season 3 days shorter.
When it snows in Sussex, Wisconsin
The first measurable snow (0.1 inch or more) in Sussex usually arrives around November 17, and the last of the season around April 9. Those are the middle dates across the winters of 1991–2020 at Germantown, WI, 8.6 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 21 days after the last snow.
Planting calendar for 53089
| When | What to do |
|---|---|
| February 19 – March 5 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 5 – March 19 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 2 – April 16 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 30 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 24 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 2 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 16 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 53089 is 5 miles from Richfield 3 SSW, WI, which stands at 984 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 53089 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°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.