USDA Hardiness Zone 4b
Frost Dates for 54891 — Washburn, Wisconsin
NOAA 1991–2020 normals from Bayfield Fish Hatchery, WI (615 ft), 7 miles northeast.
Updated
In Washburn, the last spring frost (32°F) is around May 23 in half of years and has passed by June 5 in nine years out of ten. The first fall frost comes around October 2, as early as September 17 one year in ten, leaving a typical freeze-free season of 131 days (NOAA, Bayfield Fish Hatchery, WI).
- Last spring frost
- May 23
- First fall frost
- October 2
- Growing season
- 131 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 16
- Last snow
- April 16
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
20 of 20 observed
NOAA normal
Frost risk by date in Washburn
Half of springs at Bayfield Fish Hatchery, WI see their last 32°F night by May 23; only one in ten is past it by May 8, and one in ten still has one after June 5. Planting tender crops after May 29 leaves a 30% risk of a frost on them, after June 1 20%, and after June 5 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 84% of the 182 Wisconsin stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 2 in half of years, as early as September 17 one year in ten, and holds off past October 16 one year in ten. A hard freeze of 28°F follows 12 days later, around October 14; in spring the one-in-ten date for 28°F is May 25, 11 days before the 32°F one. The freeze-free season lasts 131 days in a typical year, shorter than at 93% of the 182 Wisconsin stations; it reaches 153 days one year in ten and falls short of 112 one year in ten. On average 185 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 June 3, and return around September 22. Severe cold of 16°F or below comes every winter, usually between November 16 and April 5.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 22 | May 26 | May 29 | May 31 | Jun 3 | Jun 5 | Jun 8 | Jun 11 | Jun 17 |
| 32°F | May 8 | May 14 | May 18 | May 20 | May 23 | May 26 | May 29 | Jun 1 | Jun 5 |
| 28°F | Apr 23 | Apr 29 | May 2 | May 6 | May 9 | May 13 | May 17 | May 20 | May 25 |
| 24°F | Apr 10 | Apr 16 | Apr 20 | Apr 24 | Apr 28 | Apr 30 | May 3 | May 8 | May 15 |
| 20°F | Apr 1 | Apr 5 | Apr 8 | Apr 11 | Apr 15 | Apr 18 | Apr 22 | Apr 25 | Apr 30 |
| 16°F | Mar 25 | Mar 30 | Apr 1 | Apr 3 | Apr 5 | Apr 8 | Apr 11 | Apr 15 | Apr 20 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 7 | Sep 12 | Sep 16 | Sep 19 | Sep 22 | Sep 25 | Sep 28 | Oct 1 | Oct 5 |
| 32°F | Sep 17 | Sep 23 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 16 |
| 28°F | Sep 30 | Oct 4 | Oct 7 | Oct 11 | Oct 14 | Oct 16 | Oct 20 | Oct 24 | Oct 29 |
| 24°F | Oct 10 | Oct 16 | Oct 21 | Oct 24 | Oct 28 | Nov 1 | Nov 3 | Nov 7 | Nov 13 |
| 20°F | Oct 26 | Oct 31 | Nov 2 | Nov 5 | Nov 9 | Nov 11 | Nov 14 | Nov 17 | Nov 23 |
| 16°F | Nov 4 | Nov 7 | Nov 11 | Nov 14 | Nov 16 | Nov 18 | Nov 22 | Nov 25 | Nov 30 |
Freeze probabilities 1991–2020 at Bayfield Fish Hatchery, 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 54891 →Compare Washburn with another place →
Compared with the next station
The nearest other station, Ashland 3S, WI, 10 miles south of Washburn and 211 feet higher, has a last frost 3 days earlier (May 20), the same first-frost date, a season 2 days longer.
When it snows in Washburn, Wisconsin
The first measurable snow (0.1 inch or more) in Washburn usually arrives around November 16, and the last of the season around April 16. Those are the middle dates across the winters of 1991–2020 at Ashland 3S, WI, 9.8 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 37 days after the last snow.
Planting calendar for 54891
| When | What to do |
|---|---|
| March 14 – March 28 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 28 – April 11 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 25 – May 9 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 23 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 10 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 18 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 2 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 54891 is 7 miles from Bayfield Fish Hatchery, WI, which stands at 615 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 54891 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.