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Chill hours in S4Y

The short answer

S4Y averages 1,012 chill hours per winter (6391,330 across 10 years) in USDA zone 4a.
S4Y climate
Average chill hours1,012 (639–1,330 across 10 winters)
USDA hardiness zone4a (NRCan zone 3a)
Last spring frosttypically May 1 – May 21
First fall frosttypically September 28 – October 14

Computed from 10 winters of ERA5 hourly temperature (Open-Meteo, 2015–2025); zones from USDA PHZM 2023 / NRCan 1981–2010. Data updated July 3, 2026. See methodology.

Every variety in our database, checked against S4Y’s chill hours and zone:

How many chill hours does S4Y get?
S4Y averages 1012 chill hours per winter, ranging from 639 to 1330 across the last 10 years.
What hardiness zone is S4Y?
S4Y is in USDA hardiness zone 4a.

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Sources

  1. [1] Open-Meteo / Copernicus ERA5. Historical Weather API (hourly 2m temperature) — accessed July 2026
  2. [2] Natural Resources Canada. Plant Hardiness Zones of Canada — accessed July 2026