USDA Hardiness Zone 4a
Frost Dates for 54451 — Medford, Wisconsin
NOAA 1991–2020 normals from Medford, WI (1,470 ft), 4 miles southeast.
Updated
In Medford, the last spring frost (32°F) is around May 11 in half of years and has passed by May 26 in nine years out of ten. The first fall frost comes around October 1, as early as September 17 one year in ten, leaving a typical freeze-free season of 141 days (NOAA, Medford, WI).
- Last spring frost
- May 11
- First fall frost
- October 1
- Growing season
- 141 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
- November 14
- Last snow
- April 12
- Winters with snow
- 91%
- Snow per year
- 57"
median, 1991–2020
median, 1991–2020
20 of 22 observed
NOAA normal
Frost risk by date in Medford
Half of springs at Medford, WI see their last 32°F night by May 11; only one in ten is past it by April 29, and one in ten still has one after May 26. Planting tender crops after May 18 leaves a 30% risk of a frost on them, after May 21 20%, and after May 26 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 1 in half of years, as early as September 17 one year in ten, and holds off past October 13 one year in ten. A hard freeze of 28°F follows 10 days later, around October 11; in spring the one-in-ten date for 28°F is May 15, 11 days before the 32°F one. The freeze-free season lasts 141 days in a typical year, shorter than at 82% of the 182 Wisconsin stations; it reaches 159 days one year in ten and falls short of 124 one year in ten. On average 177 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 23, and return around September 22. Severe cold of 16°F or below comes every winter, usually between November 13 and April 2.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 8 | May 13 | May 17 | May 20 | May 23 | May 26 | May 29 | Jun 1 | Jun 6 |
| 32°F | Apr 29 | May 3 | May 5 | May 8 | May 11 | May 14 | May 18 | May 21 | May 26 |
| 28°F | Apr 18 | Apr 23 | Apr 26 | Apr 29 | May 1 | May 3 | May 6 | May 10 | May 15 |
| 24°F | Apr 5 | Apr 10 | Apr 14 | Apr 17 | Apr 20 | Apr 23 | Apr 26 | Apr 29 | May 3 |
| 20°F | Mar 28 | Apr 1 | Apr 4 | Apr 7 | Apr 9 | Apr 13 | Apr 16 | Apr 20 | Apr 25 |
| 16°F | Mar 19 | Mar 25 | Mar 29 | Mar 31 | Apr 2 | Apr 5 | Apr 7 | Apr 11 | Apr 17 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 7 | Sep 13 | Sep 16 | Sep 19 | Sep 22 | Sep 25 | Sep 28 | Oct 1 | Oct 4 |
| 32°F | Sep 17 | Sep 22 | Sep 26 | Sep 28 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 13 |
| 28°F | Sep 27 | Oct 1 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 20 | Oct 25 |
| 24°F | Oct 8 | Oct 13 | Oct 16 | Oct 20 | Oct 23 | Oct 26 | Oct 30 | Nov 1 | Nov 6 |
| 20°F | Oct 19 | Oct 25 | Oct 29 | Nov 1 | Nov 3 | Nov 5 | Nov 9 | Nov 12 | Nov 16 |
| 16°F | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 15 | Nov 17 | Nov 21 | Nov 25 |
Freeze probabilities 1991–2020 at Medford, 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 54451 →Compare Medford with another place →
Frost risk through the year in Medford
In Medford, the spring curve drops under 10% on May 26 and the fall curve passes 10% on September 17, 114 days later; that gap is shorter than at 82% of the 182 Wisconsin stations with frost dates. The spring risk falls from 90% to 10% over 27 days (April 29 to May 26) and the fall risk climbs from 10% to 90% over 26 days (September 17 to October 13): both ends of the season vary about as much. At Owen 1E, WI, 17 miles southwest, the same gap runs from May 29 to September 12, 8 days shorter.
| Planted on | Another 32°F night | 28°F night |
|---|---|---|
| Apr 27 | over 90% | 67% |
| May 4 | 75% | 37% |
| May 1150% date | 50% | 18% |
| May 18 | 30% | under 10% |
| May 25 | 12% | under 10% |
| Jun 1 | under 10% | under 10% |
Weather by month in Medford
July is the warmest month at Medford, WI, averaging 79°F by day and 57°F at night; January is the coldest at 21°F and 2°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 86% of years.
Warmth for growing adds up to 2,038 growing degree days a year (base 50°F), fewer than at 85% of the 182 Wisconsin stations. 32% of them (656) have built up by the end of June, and July adds the most, 558. Precipitation totals 34.2 inches a year, most in June (4.8") and least in January (1.1"); May to September bring 61% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 21 | 2 | 1.1 | 100% | 31 | 0 |
| Feb | 26 | 6 | 1.1 | 100% | 28 | 0 |
| Mar | 38 | 18 | 1.7 | 100% | 28 | 6 |
| Apr | 52 | 31 | 3.0 | 100% | 18 | 33 |
| May | 66 | 43 | 3.7 | 86% | 3 | 194 |
| Jun | 75 | 53 | 4.8 | 3% | 0 | 423 |
| Jul | 79 | 57 | 4.0 | 0% | 0 | 558 |
| Aug | 77 | 55 | 4.3 | 0% | 0 | 501 |
| Sep | 69 | 47 | 3.9 | 47% | 1 | 271 |
| Oct | 55 | 35 | 3.3 | 100% | 13 | 50 |
| Nov | 39 | 23 | 1.9 | 100% | 26 | 3 |
| Dec | 26 | 10 | 1.4 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Medford, WI (1,470 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, Owen 1E, WI, 17 miles southwest of Medford and 232 feet lower, has a last frost 2 days later (May 13), a first frost 5 days earlier (September 26), a season 5 days shorter.
When it snows in Medford, Wisconsin
The first measurable snow (0.1 inch or more) in Medford usually arrives around November 14, and the last of the season around April 12. Those are the middle dates across the winters of 1991–2020 at Medford, WI, 4.1 miles away: half of years saw snow earlier, half later. Snow fell in 91% of those winters. The last 32°F night of spring typically comes 29 days after the last snow.
Planting calendar for 54451
| When | What to do |
|---|---|
| March 2 – March 16 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 16 – March 30 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 13 – April 27 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 11 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 9 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 17 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 1 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 54451 is 4 miles from Medford, WI, which stands at 1,470 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 54451 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.