How many chill hours does 78638 get?

78638 averages 446 chill hours per winter, ranging from 221 to 577 across the last 10 years.

What hardiness zone is 78638?

78638 is in USDA hardiness zone 9a.

Location almanac

The short answer

78638 averages 446 chill hours per winter (221–577 across 10 years) in USDA zone 9a.

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 78638’s chill hours and zone:

Chill and zone requirements are comfortably met in 78638.

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Possible in a good year or a favorable microclimate — click through for the caveats.

How many chill hours does 78638 get?: 78638 averages 446 chill hours per winter, ranging from 221 to 577 across the last 10 years.
What hardiness zone is 78638?: 78638 is in USDA hardiness zone 9a.

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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