USDA Hardiness Zone 5b
Frost Dates for 53594 — Waterloo, Wisconsin
NOAA 1991–2020 normals from Waterloo Wwtp, WI (800 ft), under a mile west.
Updated
In Waterloo, the last spring frost (32°F) is around April 30 in half of years and has passed by May 15 in nine years out of ten. The first fall frost comes around October 9, as early as September 27 one year in ten, leaving a typical freeze-free season of 163 days (NOAA, Waterloo Wwtp, WI).
- Last spring frost
- April 30
- First fall frost
- October 9
- Growing season
- 163 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 23
- Last snow
- March 28
- Winters with snow
- 100%
- Snow per year
- 42.3"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Waterloo
Half of springs at Waterloo Wwtp, 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 15. Planting tender crops after May 5 leaves a 30% risk of a frost on them, after May 10 20%, and after May 15 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 9 in half of years, as early as September 27 one year in ten, and holds off past October 24 one year in ten. A hard freeze of 28°F follows 13 days later, around October 22; in spring the one-in-ten date for 28°F is May 4, 11 days before the 32°F one. The freeze-free season lasts 163 days in a typical year, longer than at 69% of the 182 Wisconsin stations; it reaches 183 days one year in ten and falls short of 144 one year in ten. On average 147 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 11, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 23 and March 18.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 28 | May 1 | May 4 | May 8 | May 11 | May 15 | May 18 | May 22 | May 27 |
| 32°F | Apr 16 | Apr 21 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 5 | May 10 | May 15 |
| 28°F | Apr 4 | Apr 9 | Apr 12 | Apr 15 | Apr 18 | Apr 21 | Apr 24 | Apr 29 | May 4 |
| 24°F | Mar 24 | Mar 30 | Apr 2 | Apr 3 | Apr 6 | Apr 8 | Apr 11 | Apr 16 | Apr 21 |
| 20°F | Mar 13 | Mar 18 | Mar 22 | Mar 25 | Mar 29 | Mar 31 | Apr 2 | Apr 5 | Apr 9 |
| 16°F | Mar 4 | Mar 9 | Mar 13 | Mar 15 | Mar 18 | Mar 21 | Mar 24 | Mar 28 | Apr 1 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 19 | Sep 22 | Sep 26 | Sep 28 | Oct 1 | Oct 3 | Oct 5 | Oct 7 | Oct 12 |
| 32°F | Sep 27 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 19 | Oct 24 |
| 28°F | Oct 7 | Oct 12 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 4 |
| 24°F | Oct 20 | Oct 25 | Oct 29 | Oct 31 | Nov 2 | Nov 5 | Nov 9 | Nov 12 | Nov 18 |
| 20°F | Oct 30 | Nov 2 | Nov 6 | Nov 10 | Nov 14 | Nov 17 | Nov 20 | Nov 23 | Nov 28 |
| 16°F | Nov 7 | Nov 13 | Nov 17 | Nov 21 | Nov 23 | Nov 26 | Nov 30 | Dec 3 | Dec 11 |
Freeze probabilities 1991–2020 at Waterloo 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 53594 →Compare Waterloo with another place →
Weather by month in Waterloo
July is the warmest month at Waterloo Wwtp, WI, averaging 82°F by day and 61°F at night; January is the coldest at 27°F and 11°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 45% of years.
Warmth for growing adds up to 2,611 growing degree days a year (base 50°F), more than at 73% of the 182 Wisconsin stations. 33% of them (872) have built up by the end of June, and July adds the most, 663. Precipitation totals 38.3 inches a year, most in June (5.6") and least in January (1.4"); May to September bring 58% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 27 | 11 | 1.4 | 100% | 30 | 0 |
| Feb | 31 | 14 | 1.6 | 100% | 27 | 1 |
| Mar | 43 | 24 | 2.0 | 100% | 24 | 15 |
| Apr | 57 | 35 | 3.9 | 100% | 11 | 59 |
| May | 69 | 46 | 4.2 | 45% | 1 | 267 |
| Jun | 79 | 57 | 5.6 | 0% | 0 | 530 |
| Jul | 82 | 61 | 4.4 | 0% | 0 | 663 |
| Aug | 81 | 59 | 4.1 | 0% | 0 | 614 |
| Sep | 73 | 50 | 3.9 | 16% | 0 | 349 |
| Oct | 61 | 38 | 3.0 | 97% | 6 | 100 |
| Nov | 45 | 28 | 2.4 | 100% | 20 | 13 |
| Dec | 33 | 18 | 1.8 | 100% | 28 | 0 |
Monthly normals 1991–2020 at Waterloo Wwtp, WI (800 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, Lake Mills Wwtp, WI, 8 miles southeast of Waterloo, has a last frost 1 day earlier (April 29), a first frost 5 days later (October 14), a season 4 days longer.
When it snows in Waterloo, Wisconsin
The first measurable snow (0.1 inch or more) in Waterloo usually arrives around November 23, and the last of the season around March 28. Those are the middle dates across the winters of 1991–2020 at Lake Mills Wwtp, WI, 8.3 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 33 days after the last snow.
Planting calendar for 53594
| 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 17 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 25 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 9 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 53594 is under a mile from Waterloo Wwtp, WI, which stands at 800 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 53925 (Columbus). The 2023 USDA Plant Hardiness Zone Map lists ZIP 53594 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.