Frost Dates for 98903 — Yakima, Washington

Half of springs at Yakima #2, WA see their last 32°F night by April 8; only one in ten is past it by March 23, and one in ten still has one after April 28. Planting tender crops after April 18 leaves a 30% risk of a frost on them, after April 22 20%, and after April 28 10%. The 20 days between the even-odds date and the one-in-ten date is wider than at 52% of the 113 Washington stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 23 in half of years, as early as October 9 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 11 days later, around November 3; in spring the one-in-ten date for 28°F is April 6, 22 days before the 32°F one. The freeze-free season lasts 196 days in a typical year, longer than at 53% of the 113 Washington stations; it reaches 218 days one year in ten and falls short of 172 one year in ten. On average 109 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 20 days longer, to about April 28, and return around October 12. Severe cold of 16°F or below comes in 91% of winters, usually between December 11 and January 17.

July is the warmest month at Yakima #2, WA, averaging 88°F by day and 60°F at night; December is the coldest at 38°F and 26°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 71% of years.

Warmth for growing adds up to 3,038 growing degree days a year (base 50°F), more than at 90% of the 113 Washington stations. 32% of them (979) have built up by the end of June, and July adds the most, 744. Precipitation totals 8.6 inches a year, most in December (1.4") and least in August (0.2"); May to September bring 26% of it.

The nearest other station, Selah 2 NE, WA, 10 miles northeast of Yakima, has a last frost 27 days later (May 5), a first frost 19 days earlier (October 4), a season 47 days shorter.

The first measurable snow (0.1 inch or more) in Yakima usually arrives around November 25, and the last of the season around March 1. Those are the middle dates across the winters of 1991–2020 at Yakima Air Terminal, WA, 3.9 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 38 days after the last snow.

ZIP 98903 is 4 miles from Yakima #2, WA, which stands at 1,142 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 98902 (Yakima). The 2023 USDA Plant Hardiness Zone Map lists ZIP 98903 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.