USDA Hardiness Zone 4b
Frost Dates for 54521 — Eagle River, Wisconsin
NOAA 1991–2020 normals from Eagle Rvr, WI (1,623 ft), under a mile southwest.
Updated
In Eagle River, the last spring frost (32°F) is around May 25 in half of years and has passed by June 6 in nine years out of ten. The first fall frost comes around September 24, as early as September 8 one year in ten, leaving a typical freeze-free season of 121 days (NOAA, Eagle Rvr, WI).
- Last spring frost
- May 25
- First fall frost
- September 24
- Growing season
- 121 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 8
- Last snow
- April 18
- Winters with snow
- 100%
- Snow per year
- 76.5"
median, 1991–2020
median, 1991–2020
28 of 28 observed
NOAA normal
Frost risk by date in Eagle River
Half of springs at Eagle Rvr, WI see their last 32°F night by May 25; only one in ten is past it by May 10, and one in ten still has one after June 6. Planting tender crops after May 30 leaves a 30% risk of a frost on them, after June 2 20%, and after June 6 10%. The 12 days between the even-odds date and the one-in-ten date is the narrowest of the 182 Wisconsin stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 24 in half of years, as early as September 8 one year in ten, and holds off past October 7 one year in ten. A hard freeze of 28°F follows 11 days later, around October 5; in spring the one-in-ten date for 28°F is May 26, 11 days before the 32°F one. The freeze-free season lasts 121 days in a typical year, shorter than at 98% of the 182 Wisconsin stations; it reaches 141 days one year in ten and falls short of 101 one year in ten. On average 191 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 10 days longer, to about June 4, and return around September 12. Severe cold of 16°F or below comes every winter, usually between November 8 and April 13.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 23 | May 26 | May 29 | Jun 1 | Jun 4 | Jun 7 | Jun 10 | Jun 14 | Jun 20 |
| 32°F | May 10 | May 16 | May 20 | May 22 | May 25 | May 27 | May 30 | Jun 2 | Jun 6 |
| 28°F | Apr 30 | May 4 | May 7 | May 10 | May 13 | May 16 | May 18 | May 22 | May 26 |
| 24°F | Apr 19 | Apr 24 | Apr 28 | Apr 30 | May 2 | May 5 | May 8 | May 11 | May 15 |
| 20°F | Apr 8 | Apr 13 | Apr 16 | Apr 19 | Apr 22 | Apr 25 | Apr 28 | May 1 | May 6 |
| 16°F | Mar 31 | Apr 4 | Apr 7 | Apr 10 | Apr 13 | Apr 15 | Apr 18 | Apr 22 | Apr 26 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 26 | Sep 1 | Sep 5 | Sep 9 | Sep 12 | Sep 15 | Sep 18 | Sep 22 | Sep 27 |
| 32°F | Sep 8 | Sep 14 | Sep 18 | Sep 21 | Sep 24 | Sep 27 | Oct 1 | Oct 3 | Oct 7 |
| 28°F | Sep 20 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 15 | Oct 20 |
| 24°F | Oct 2 | Oct 7 | Oct 11 | Oct 14 | Oct 17 | Oct 21 | Oct 24 | Oct 29 | Nov 3 |
| 20°F | Oct 15 | Oct 21 | Oct 25 | Oct 29 | Nov 1 | Nov 3 | Nov 5 | Nov 8 | Nov 13 |
| 16°F | Oct 28 | Nov 1 | Nov 4 | Nov 6 | Nov 8 | Nov 12 | Nov 14 | Nov 17 | Nov 22 |
Freeze probabilities 1991–2020 at Eagle Rvr, 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 54521 →Compare Eagle River with another place →
Weather by month in Eagle River
July is the warmest month at Eagle Rvr, WI, averaging 78°F by day and 54°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 May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 24% of years.
Warmth for growing adds up to 1,723 growing degree days a year (base 50°F), fewer than at 97% of the 182 Wisconsin stations. 32% of them (551) have built up by the end of June, and July adds the most, 496. Precipitation totals 32.3 inches a year, most in June (4.1") and least in February (1.1"); May to September bring 57% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 21 | 2 | 1.3 | 100% | 31 | 0 |
| Feb | 26 | 3 | 1.1 | 100% | 28 | 0 |
| Mar | 37 | 13 | 1.6 | 100% | 29 | 3 |
| Apr | 50 | 26 | 2.8 | 100% | 23 | 17 |
| May | 65 | 39 | 3.5 | 98% | 7 | 155 |
| Jun | 75 | 50 | 4.1 | 24% | <1 | 376 |
| Jul | 78 | 54 | 4.0 | 0% | 0 | 496 |
| Aug | 75 | 52 | 3.2 | 1% | 0 | 425 |
| Sep | 67 | 44 | 3.6 | 69% | 2 | 213 |
| Oct | 53 | 33 | 3.6 | 100% | 15 | 37 |
| Nov | 38 | 21 | 1.9 | 100% | 26 | 2 |
| Dec | 26 | 10 | 1.6 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Eagle Rvr, WI (1,623 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, St Germain, WI, 12 miles west of Eagle River, has a last frost 6 days earlier (May 19), a first frost 9 days later (October 3), a season 15 days longer.
When it snows in Eagle River, Wisconsin
The first measurable snow (0.1 inch or more) in Eagle River usually arrives around November 8, and the last of the season around April 18. Those are the middle dates across the winters of 1991–2020 at Eagle Rvr, WI, 0.6 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 37 days after the last snow.
Planting calendar for 54521
| When | What to do |
|---|---|
| March 16 – March 30 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 30 – April 13 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 27 – May 11 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 25 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 2 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 10 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 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 54521 is under a mile from Eagle Rvr, WI, which stands at 1,623 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 54521 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.