Frost Dates for 54501 — Rhinelander, Wisconsin

Half of springs at Rhinelander Oneida Airport, WI see their last 32°F night by May 26; only one in ten is past it by May 9, and one in ten still has one after June 8. Planting tender crops after June 1 leaves a 30% risk of a frost on them, after June 4 20%, and after June 8 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 September 23 in half of years, as early as September 5 one year in ten, and holds off past October 7 one year in ten. A hard freeze of 28°F follows 9 days later, around October 2; in spring the one-in-ten date for 28°F is May 29, 10 days before the 32°F one. The freeze-free season lasts 120 days in a typical year, shorter than at 99% of the 182 Wisconsin stations; it reaches 142 days one year in ten and falls short of 99 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 10 days longer, to about June 5, and return around September 9. Severe cold of 16°F or below comes every winter, usually between November 8 and April 8.

July is the warmest month at Rhinelander Oneida Airport, WI, averaging 80°F by day and 54°F at night; January is the coldest at 23°F and 4°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 31% of years.

Warmth for growing adds up to 1,880 growing degree days a year (base 50°F), fewer than at 91% of the 182 Wisconsin stations. 32% of them (600) have built up by the end of June, and July adds the most, 528. Precipitation totals 29.7 inches a year, most in July (4.0") and least in January (0.8"); May to September bring 60% of it.

The nearest other station, Rice Rsvr Tomahawk-2, WI, 18 miles southwest of Rhinelander, has a last frost 16 days earlier (May 10), a first frost 11 days later (October 4), a season 26 days longer.

The first measurable snow (0.1 inch or more) in Rhinelander usually arrives around October 29, and the last of the season around April 23. Those are the middle dates across the winters of 1991–2020 at Rhinelander 4NE, WI, 4.2 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.

ZIP 54501 is 4 miles from Rhinelander Oneida Airport, WI, which stands at 1,599 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 54501 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.