How many chill hours does 99581 get?

99581 averages 1181 chill hours per winter, ranging from 819 to 1403 across the last 10 years.

What hardiness zone is 99581?

99581 is in USDA hardiness zone 4a.

Location almanac

The short answer

99581 averages 1,181 chill hours per winter (819–1,403 across 10 years) in USDA zone 4a.

99581 climate
Average chill hours	1,181 (819–1,403 across 10 winters)
USDA hardiness zone	4a
Last spring frost	typically May 8 – June 3
First fall frost	typically September 25 – October 16

Computed from 10 winters of ERA5 hourly temperature (Open-Meteo, 2015–2025); zones from USDA PHZM 2023. Data updated July 3, 2026. See methodology.

Every variety in our database, checked against 99581’s chill hours and zone:

Chill and zone requirements are comfortably met in 99581.

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How many chill hours does 99581 get?: 99581 averages 1181 chill hours per winter, ranging from 819 to 1403 across the last 10 years.
What hardiness zone is 99581?: 99581 is in USDA hardiness zone 4a.

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[1] Open-Meteo / Copernicus ERA5. Historical Weather API (hourly 2m temperature) — accessed July 2026
[2] USDA / PRISM (Oregon State University). 2023 USDA Plant Hardiness Zone Map — accessed July 2026