May 21, 2024 – Thunder Bay Rainfall Warning Update: Prepare for Heavy Rain and Strong Winds


Rainfall Warning in Effect for the City of Thunder Bay

Heavy Rain and Strong Winds Expected Beginning This Evening

THUNDER BAY – WEATHER – A rainfall warning is currently in effect for the City of Thunder Bay, as a strong low-pressure system is expected to bring significant weather changes starting this evening. Heavy rain, accumulating up to 50 mm, will begin tonight and persist through Wednesday evening. In addition to the heavy rain, strong easterly winds gusting up to 70 km/h will develop tonight. By Wednesday morning, these winds will shift to a southerly direction before gradually diminishing in the evening.


  • Total rainfall amounts near 50 mm
  • Wind gusts up to 70 km/h


  • This evening through Wednesday evening

Flood Watch Alert Issued

The Lakehead Region Conservation Authority has issued a Flood Watch for the Lakehead Region including: City of Thunder Bay, Municipalities of Neebing, Oliver Paipoonge, Shuniah and the Townships of O’Connor, Conmee, Gillies and Dorion.

In addition the Ministry of Natural Resources and Forestry has issued a flood watch in the Thunder Bay Ignace District as well as for Upsala, Raith, Ignace, Armstrong and Gull Bay.

The flood watch will remain in effect until Thursday May 23rd, at 12:00 hrs

Description of Weather System

A low pressure system is moving into Northwestern Ontario bringing rainfall across the district with amounts potentially in the range of 50 – 80mm.  Some areas may also receive significant thunderstorms bringing additional rainfall amounts.  Conditions are expected to persist for the next 24 hours.  This system could also be accompanied by winds reaching up to 70km/hr.

Description of Current Conditions

High-intensity and/or significant amounts of rainfall can lead to increased runoff, streamflow and flooding of low-lying areas and water pooling over roads.   Any travellers should be cautious of reduced visibility during periods of high rain and potential hazards associated with water overtopping roads.  Flying debris from high winds can be a safety hazard.

There is also potential for thunderstorms producing an additional 25 to 50 millimetres of precipitation. Localized thunderstorms may also occur which could result in higher amounts in some areas.

Potential Impacts:

  • Loose objects may be tossed by the wind, causing injury or damage.
  • Utility outages may occur due to strong winds.
  • Heavy downpours could lead to flash floods and water pooling on roads.
  • Localized flooding in low-lying areas is possible.
  • Reduced visibility while driving; motorists should slow down, watch for tail lights, and be prepared to stop.

Precautions and Recommendations:

Residents are advised to secure loose objects around their property and stay informed about potential flooding by consulting their local Conservation Authority or the Ontario Ministry of Natural Resources and Forestry office. Up-to-date flood information is available at

If you must drive during this period, exercise extreme caution. Slow down in areas of reduced visibility and avoid roads with significant water pooling.

Weather Trivia:

Did you know that the highest recorded rainfall in a 24-hour period for Thunder Bay was 83 mm on July 26, 2006? This event caused significant flooding and property damage across the region, highlighting the importance of being prepared for heavy rainfall events.

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