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Ontario · climate station 611HBEC · 213.4 m

Thornbury Slama

Average last spring frostMay 11
Average first fall frostOctober 11
Frost-free period152 days

1981–2010 normals; ECCC quality code “D” (A = WMO “3 and 5 rule”; B ≥ 25 years; C ≥ 20 years; D ≥ 15 years of data). An average is not a guarantee: a late frost is still possible.

Probabilities

10%25%33%50%66%75%90%
Spring frost (0 °C or lower) on or afterMay 24May 18May 14May 9May 5May 3April 29
Fall frost on or beforeSeptember 28October 4October 8October 12October 16October 18November 1
Frost-free period ≤ (days)133147149155158161176

Example: the spring 10% column is the date after which a frost occurs in only one year in ten.

Indicative planting calendar

Start tomatoes, peppers and eggplant indoorsMarch 16 – March 30
Sow peas, spinach, lettuce and radish outdoors (frost-tolerant)April 13 – April 27
Plant potatoes and onion setsApril 27 – May 11
Transplant tomatoes and peppers; sow beans, corn, squash and cucumbersMay 18 – June 1
Last sowing of quick crops (radish, lettuce, spinach)August 27 – September 11
Harvest or cover frost-tender cropsOctober 4 – October 11
Plant garlic and spring bulbsOctober 11 – November 8

General gardening rules of thumb computed from this station's average last/first frost dates; they are not ECCC data. Adjust to local conditions and seed-packet instructions.

Nearby stations

Proton Station · 107 dOwen Sound Moe · 162 dTara · 131 dWiarton A · 148 dHanover · 124 dBarrie Wpcc · 153 d
Sources & licences

Environment and Climate Change Canada — Canadian Climate Normals 1981–2010 (station data, MSC Datamart) (30-year averages; not updated). Retrieved 2026-10-18 19:09 UTC.
Data Source: Environment and Climate Change Canada Environment and Climate Change Canada Data Servers End-use Licence.

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