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Monthly climate in St. Thomas, Ontario, Canada

Last updated: March 2, 2024

Under the Köppen–Geiger climate classification St. Thomas features a humid continental climate (Dfb). Temperatures typically range between -3 °C (27 °F) and 22 °C (72 °F) through the year, but rarely can drop to -22 °C (-7 °F) or can rise to as high as 31 °C (87 °F). The average annual precipitation amounts to about 1100 mm (43.3 inches) and receives 145 rainy days on the 1 mm (0.04 inches) threshold annually. St. Thomas enjoys an average of 2885 hours of sunshine throughout the year, and daylight varies from 9 hours 5 minutes to 15 hours 15 minutes per day.

Monthly average temperatures in St. Thomas, Ontario, Canada §

The warmest months in St. Thomas are June, July and August, with daily mean temperatures ranging from 19 to 22 °C (66 - 72 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from -3 to 1 °C (27 - 34 °F) throughout the day. On average each year, St. Thomas experiences 38 days above 25 °C (77.0 °F) and 99 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in St. Thomas, Ontario, Canada. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to June 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Maximum 11°C
(51°F)		 13°C
(56°F)		 15°C
(59°F)		 20°C
(68°F)		 26°C
(78°F)		 28°C
(84°F)		 31°C
(87°F)		 29°C
(84°F)		 29°C
(85°F)		 26°C
(78°F)		 19°C
(66°F)		 13°C
(56°F)
Mean maximum 8°C
(47°F)		 9°C
(48°F)		 12°C
(55°F)		 17°C
(63°F)		 24°C
(76°F)		 27°C
(81°F)		 29°C
(85°F)		 28°C
(83°F)		 27°C
(81°F)		 23°C
(75°F)		 15°C
(60°F)		 11°C
(52°F)
Average high -0°C
(32°F)		 0°C
(33°F)		 4°C
(40°F)		 9°C
(49°F)		 16°C
(61°F)		 22°C
(72°F)		 25°C
(78°F)		 25°C
(77°F)		 22°C
(71°F)		 15°C
(60°F)		 7°C
(45°F)		 3°C
(37°F)
Daily mean -3°C
(27°F)		 -3°C
(27°F)		 1°C
(34°F)		 6°C
(43°F)		 13°C
(55°F)		 19°C
(66°F)		 22°C
(72°F)		 22°C
(71°F)		 18°C
(65°F)		 12°C
(55°F)		 5°C
(41°F)		 1°C
(34°F)
Average low -5°C
(23°F)		 -6°C
(22°F)		 -2°C
(29°F)		 3°C
(38°F)		 9°C
(49°F)		 15°C
(60°F)		 19°C
(66°F)		 18°C
(65°F)		 15°C
(60°F)		 10°C
(49°F)		 2°C
(36°F)		 -1°C
(30°F)
Mean minimum -16°C
(3°F)		 -16°C
(4°F)		 -10°C
(15°F)		 -3°C
(27°F)		 2°C
(35°F)		 10°C
(51°F)		 15°C
(58°F)		 13°C
(55°F)		 9°C
(48°F)		 2°C
(37°F)		 -5°C
(23°F)		 -8°C
(18°F)
Minimum -21°C
(-6°F)		 -22°C
(-7°F)		 -14°C
(7°F)		 -6°C
(21°F)		 -1°C
(31°F)		 7°C
(44°F)		 14°C
(57°F)		 11°C
(52°F)		 5°C
(42°F)		 1°C
(35°F)		 -8°C
(18°F)		 -16°C
(4°F)

Compare climate in St. Thomas with other places

Compare temperature, precipitation, sunshine, UV index in St. Thomas, Ontario, Canada with other places around the world.

Monthly average precipitation in St. Thomas, Ontario, Canada §

St. Thomas usually has the most precipitation in April, May and October, with an average of 13 rainy days and 110 mm (4.3 inches) of precipitation per month. The driest months in St. Thomas are January, February and December. On average, 78 mm (3.1 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in St. Thomas, Ontario, Canada. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average precipitation mm (inches) 76 (3.0) 79 (3.1) 81 (3.2) 106 (4.2) 99 (3.9) 93 (3.7) 91 (3.6) 96 (3.8) 82 (3.2) 123 (4.9) 94 (3.7) 77 (3.0)
Average precipitation days (≥ 1 mm) 11 12 11 13 13 12 12 11 10 15 12 13

Monthly sunshine hours in St. Thomas, Ontario, Canada §

The sunniest months in St. Thomas are June, July and August, when the sun shines an average of 11 hours 21 minutes a day. Least sunny months in St. Thomas: January, February and December receive an average of 4 hours 7 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in St. Thomas, Ontario, Canada. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Mean monthly sunshine hours 101 152 239 254 298 344 357 343 297 221 153 121
Mean daily daylight hours 9h 26m 10h 33m 11h 58m 13h 24m 14h 38m 15h 15m 14h 55m 13h 49m 12h 25m 10h 59m 9h 43m 9h 5m

Solar UV radiation in St. Thomas, Ontario, Canada §

St. Thomas experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 9 - 10, which corresponds to the Very High category of sun exposure. January, February and December are in the Low / Moderate exposure category. In these months, the maximum values of the UV index do not exceed 4. For more detailed information, check out our hourly St. Thomas UV Index data.

Average daily maximum UV levels by month for St. Thomas, Ontario, Canada. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2022 to January 2023.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
UV Index (month maximum) 3 4 5 8 9 10 10 9 8 6 4 2

Detailed Monthly Weather Insights for St. Thomas, Ontario, Canada

Discover in-depth weather details for every month in St. Thomas. Click through the links below for comprehensive overviews of temperature trends, precipitation levels, sunshine hours, and solar UV radiation specifics. Whether planning a visit or simply curious about St. Thomas's climate nuances, these monthly breakdowns provide the information you need for an informed understanding of what to expect throughout the year.

Each link leads to a detailed account of the typical weather conditions for that month, providing both locals and tourists with vital information to plan their daily activities, wardrobe, and travel itineraries accordingly.