Frost Dates for 83858 — Rathdrum, Idaho

Half of springs at Coeur D'Alene, ID see their last 32°F night by April 22; only one in ten is past it by April 4, and one in ten still has one after May 6. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 2 20%, and after May 6 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 93% of the 67 Idaho stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 18 in half of years, as early as October 4 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 14 days later, around November 1; in spring the one-in-ten date for 28°F is April 21, 15 days before the 32°F one. The freeze-free season lasts 179 days in a typical year, longer than at 91% of the 67 Idaho stations; it reaches 202 days one year in ten and falls short of 158 one year in ten. On average 120 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 15 days longer, to about May 7, and return around October 6. Severe cold of 16°F or below comes in 98% of winters, usually between December 8 and February 15.

July is the warmest month at Coeur D'Alene, ID, averaging 83°F by day and 57°F at night; January is the coldest at 36°F and 26°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 25% of years.

Warmth for growing adds up to 2,202 growing degree days a year (base 50°F), fewer than at 51% of the 67 Idaho stations. 26% of them (573) have built up by the end of June, and July adds the most, 621. Precipitation totals 25.3 inches a year, most in December (3.5") and least in July (0.7"); May to September bring 26% of it.

The nearest other station, Bayview Model Basin, ID, 19 miles northeast of Rathdrum, has a last frost 30 days later (May 22), a first frost 26 days earlier (September 22), a season 57 days shorter.

The first measurable snow (0.1 inch or more) in Rathdrum usually arrives around November 28, and the last of the season around March 1. Those are the middle dates across the winters of 1991–2020 at Coeur D'Alene, ID, 10.2 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 52 days after the last snow.

ZIP 83858 is 10 miles from Coeur D'Alene, ID, which stands at 2,133 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 83854 (Post Falls). The 2023 USDA Plant Hardiness Zone Map lists ZIP 83858 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.