Frost Dates for 99122 — Davenport, Washington

Half of springs at Davenport, WA see their last 32°F night by June 6; only one in ten is past it by May 13, and one in ten still has one after July 5. Planting tender crops after June 17 leaves a 30% risk of a frost on them, after June 24 20%, and after July 5 10%. The 29 days between the even-odds date and the one-in-ten date is wider than at 96% of the 113 Washington stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by September 11 in half of years, as early as August 26 one year in ten, and holds off past September 28 one year in ten. A hard freeze of 28°F follows 16 days later, around September 27; in spring the one-in-ten date for 28°F is June 2, 33 days before the 32°F one. The freeze-free season lasts 94 days in a typical year, the shortest of the 113 Washington stations; it reaches 126 days one year in ten and falls short of 66 one year in ten. On average 175 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between November 5 and March 3.

July is the warmest month at Davenport, WA, averaging 82°F by day and 48°F at night; December is the coldest at 31°F and 19°F. A freezing night is all but certain in every month from September to May (a 90% chance or more). No month is safe from a 32°F night: even the warmest has at least a 10% chance. In spring, June still brings one in 57% of years and July still brings one in 14% of years.

Warmth for growing adds up to 1,574 growing degree days a year (base 50°F), fewer than at 85% of the 113 Washington stations. 25% of them (387) have built up by the end of June, and August adds the most, 469. Precipitation totals 14.0 inches a year, most in December (1.9") and least in August (0.3"); May to September bring 27% of it.

The nearest other station, Spokane WFO, WA, 26 miles east of Davenport, has a last frost 27 days earlier (May 10), a first frost 15 days later (September 26), a season 43 days longer.

The first measurable snow (0.1 inch or more) in Davenport usually arrives around November 18, and the last of the season around March 8. Those are the middle dates across the winters of 1991–2020 at Davenport, WA, 1.6 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 90 days after the last snow.

ZIP 99122 is 2 miles from Davenport, WA, which stands at 2,369 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 99122 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.