Clear Creek, ON F1 Tornado of August 4, 1999

Simcoe - Delhi - Norfolk

This tornado developed as a waterspout over Lake Erie at 11:30am, then moved ashore and travelled for 5 km with a path that was 100m wide. Witnesses captured photographs of the twister, a highly photogenic cone tornado that was classic in appearance and fully condensed to the ground.

A house was shifted slightly off of its foundation and had windows shattered, as well as shingles and siding torn off. A shed was destroyed, farm equipment scattered, crops were levelled and trees snapped and uprooted.

This was one of three tornadoes that touched down in Southern Ontario on August 4; the others were an F1 on Hamilton Mountain, and an F2 that struck Flamborough and Burlington.

Figure 2 depicts the surface observations at 2:00 pm, which shows a low pressure system exiting Ontario with a cold front across Lake Erie. The low pressure would have brought southwesterly winds across Toronto and Hamilton, which could have activated the lake-breezes across Lake Ontario. Figure 2 depicts an ongoing thunderstorm over Hamilton (marked as an “R”), which is responsible for this F1 tornado.

Figure 2. Surface analysis at 18Z on August 4, 1999 showing mean sea-level pressure (MSLP) contours, surface observations, fronts and pressure centres (WPC, 2017)

According to Environment and Climate Change Canada (2018), an F1 tornado touched down at 11:30 am EDT near Clear Creek, ON. The tornado travelled for 5 km with a maximum width of 100 metres. The tornado caused no fatalities or injuries, but caused $75 thousand dollars in property damage.


Michiel, B. (August 4, 1999). York University: Tornadoes of Southern Ontario. Retrieved from:

NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 18Z Wed Aug 4 1999. Retrieved from:

Environment and Climate Change Canada Data. (2018). Canadian National Tornado Database: Verified Events (1980-2009) – Public. Retrieved from: