USDA Hardiness Zone 6a
Frost Dates for 53092 — Mequon, Wisconsin
NOAA 1991–2020 normals from Grafton Wwtp, WI (741 ft), 6 miles north.
Updated
In Mequon, the last spring frost (32°F) is around April 23 in half of years and has passed by May 9 in nine years out of ten. The first fall frost comes around October 24, as early as October 8 one year in ten, leaving a typical freeze-free season of 182 days (NOAA, Grafton Wwtp, WI).
- Last spring frost
- April 23
- First fall frost
- October 24
- Growing season
- 182 days
- Hardiness zone
- 6a
50% probability
50% probability
freeze-free, 50%
-10 to -5°F (-23.3 to -20.6°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 Mequon
Half of springs at Grafton Wwtp, WI see their last 32°F night by April 23; only one in ten is past it by April 10, and one in ten still has one after May 9. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 3 20%, and after May 9 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 24 in half of years, as early as October 8 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 9 days later, around November 2; in spring the one-in-ten date for 28°F is April 24, 15 days before the 32°F one. The freeze-free season lasts 182 days in a typical year, longer than at 97% of the 182 Wisconsin stations; it reaches 200 days one year in ten and falls short of 161 one year in ten. On average 134 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 5, and return around October 11. Severe cold of 16°F or below comes every winter, usually between November 29 and March 15.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 20 | Apr 26 | Apr 30 | May 2 | May 5 | May 9 | May 13 | May 17 | May 23 |
| 32°F | Apr 10 | Apr 15 | Apr 17 | Apr 20 | Apr 23 | Apr 27 | Apr 30 | May 3 | May 9 |
| 28°F | Mar 31 | Apr 3 | Apr 6 | Apr 8 | Apr 11 | Apr 14 | Apr 16 | Apr 19 | Apr 24 |
| 24°F | Mar 18 | Mar 23 | Mar 28 | Mar 31 | Apr 2 | Apr 3 | Apr 6 | Apr 9 | Apr 13 |
| 20°F | Mar 9 | Mar 13 | Mar 17 | Mar 20 | Mar 23 | Mar 26 | Mar 30 | Apr 1 | Apr 5 |
| 16°F | Mar 2 | Mar 7 | Mar 10 | Mar 13 | Mar 15 | Mar 18 | Mar 21 | Mar 25 | Mar 30 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 27 | Oct 1 | Oct 6 | Oct 9 | Oct 11 | Oct 14 | Oct 17 | Oct 21 | Oct 26 |
| 32°F | Oct 8 | Oct 14 | Oct 18 | Oct 21 | Oct 24 | Oct 26 | Oct 29 | Nov 1 | Nov 5 |
| 28°F | Oct 21 | Oct 26 | Oct 29 | Oct 31 | Nov 2 | Nov 5 | Nov 7 | Nov 11 | Nov 15 |
| 24°F | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 12 | Nov 14 | Nov 17 | Nov 21 | Nov 25 |
| 20°F | Nov 8 | Nov 13 | Nov 16 | Nov 19 | Nov 21 | Nov 23 | Nov 26 | Nov 30 | Dec 5 |
| 16°F | Nov 15 | Nov 20 | Nov 23 | Nov 26 | Nov 29 | Dec 1 | Dec 5 | Dec 11 | Dec 18 |
Freeze probabilities 1991–2020 at Grafton 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 53092 →Compare Mequon with another place →
Weather by month in Mequon
July is the warmest month at Grafton Wwtp, WI, averaging 81°F by day and 62°F at night; January is the coldest at 30°F and 17°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 27% of years.
Warmth for growing adds up to 2,586 growing degree days a year (base 50°F), more than at 69% of the 182 Wisconsin stations. 29% of them (742) have built up by the end of June, and July adds the most, 668.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 30 | 17 | 100% | 29 | 0 |
| Feb | 33 | 19 | 100% | 26 | 0 |
| Mar | 43 | 26 | 100% | 22 | 11 |
| Apr | 54 | 36 | 100% | 8 | 42 |
| May | 66 | 46 | 27% | <1 | 216 |
| Jun | 76 | 56 | 0% | 0 | 473 |
| Jul | 81 | 62 | 0% | 0 | 668 |
| Aug | 80 | 61 | 0% | 0 | 628 |
| Sep | 73 | 54 | 2% | 0 | 399 |
| Oct | 61 | 43 | 78% | 4 | 134 |
| Nov | 46 | 31 | 100% | 17 | 16 |
| Dec | 35 | 21 | 100% | 27 | 0 |
Monthly normals 1991–2020 at Grafton Wwtp, WI (741 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, Germantown, WI, 9 miles west of Mequon, has a last frost 13 days later (May 6), a first frost 16 days earlier (October 8), a season 28 days shorter.
When it snows in Mequon, Wisconsin
The first measurable snow (0.1 inch or more) in Mequon 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, 8.7 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 14 days after the last snow.
Planting calendar for 53092
| When | What to do |
|---|---|
| February 12 – February 26 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 26 – March 12 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 26 – April 9 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 23 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 1 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 10 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 24 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 53092 is 6 miles from Grafton Wwtp, WI, which stands at 741 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 53092 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°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.