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Ontario · climate station 6100971 · 96.0 m

Brockville Pcc

Average last spring frostApril 28
Average first fall frostOctober 12
Frost-free period166 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 14May 5April 29April 27April 24April 23April 17
Fall frost on or beforeOctober 1October 5October 6October 14October 20October 22November 4
Frost-free period ≤ (days)147160162166172180189

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 3 – March 17
Sow peas, spinach, lettuce and radish outdoors (frost-tolerant)March 31 – April 14
Plant potatoes and onion setsApril 14 – April 28
Transplant tomatoes and peppers; sow beans, corn, squash and cucumbersMay 5 – May 19
Last sowing of quick crops (radish, lettuce, spinach)August 28 – September 12
Harvest or cover frost-tender cropsOctober 5 – October 12
Plant garlic and spring bulbsOctober 12 – November 9

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

Lyndhurst Shawmere · 158 dOttawa Macdonald-Cartier Int'l A · 159 dMorrisburg · 133 dOttawa Cda · 158 dRussell · 144 dKingston Pumping Station · 169 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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