Monthly weather forecast and climate
Thunder Bay, Canada

What is the coldest month in Thunder Bay?

With an average high-temperature of -8°C (17.6°F) and an average low-temperature of -20.6°C (-5.1°F), January is the coldest month.

How much does it rain in Thunder Bay?

Throughout the year, in Thunder Bay, there are 92.6 rainfall days, and 546.5mm (21.5") of precipitation is accumulated.

What is the driest month in Thunder Bay?

The month with the least rainfall is January when the rain falls for 0.6 days and typically collects 0.4mm (0") of precipitation.

When does it snow in Thunder Bay?

January through May, September through December are months with snowfall.

How many days does it snow in Thunder Bay?

Throughout the year, there are 62.7 snowfall days, and 1631mm (64.2") of snow is accumulated.

What months are the sea coldest in Thunder Bay?

January through April, with an average sea temperature of 2°C (35.6°F), are months with the coldest seawater. For swimming, this is considered life-threatening and very dangerous. The water feels painfully cold, and hyperventilation quickly occurs. A specialized swimsuit is mandatory to reduce thermal damage.

What is the warmest month in Thunder Bay?

July is the warmest month, with an average high-temperature of 24.3°C (75.7°F) and an average low-temperature of 11.1°C (52°F).

What is the wettest month in Thunder Bay?

August is the month with the most rainfall. Rain falls for 12.3 days and accumulates 89.5mm (3.5") of precipitation.

When is the sea warmest in Thunder Bay?

Months with the warmest seawater are August and September, with an average sea temperature of 13°C (55.4°F). Swimming in 13°C (55.4°F) is considered dangerous. Unprotected immersion in temperatures below 10°C (50°F) causes quickly maximum intensity cold shock with hyperventilation.

When does it snow the most in Thunder Bay?

December is the month with the most snowfall. Snow falls for 13.9 days and accumulates 389mm (15.3") of snow.
Average temperature - Thunder Bay, Canada
Average rainfall - Thunder Bay, Canada

The wettest month (with the highest rainfall) is August (89.5mm).
The driest month (with the lowest rainfall) is January (0.4mm).

Average rainfall days - Thunder Bay, Canada

The month with the highest number of rainy days is June (13.8 days).
The month with the lowest number of rainy days is January (0.6 days).

Average snowfall - Thunder Bay, Canada
Average snowfall days - Thunder Bay, Canada

The month with the highest number of snowfall days is December (13.9 days).
Months with the lowest number of snowfall days are June, July and August (0 days).

Average sea temperature - Thunder Bay, Canada

Best months for swimming (with the highest average sea temperature) are August and September (13°C).
Coldest months (with the lowest average sea temperature) are January, February, March and April (2°C).

Average daylight / Average sunshine - Thunder Bay, Canada

The month with the longest days is June (Average daylight: 16h).
The month with shortest days is December (Average daylight: 8.4h).

The month with most sunshine is June (Average sunshine: 8.7h).
Months with least sunshine are November and December (Average sunshine: 2.9).

Average UV index - Thunder Bay, Canada
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