Ontario Provincial Police officers reportedly observed this tornado at 12:00 pm. It tracked for 1.5 km through the Devil’s Pulpit Golf Club, uprooting several dozen trees and causing other minor property damage, including a small silo that was picked up and thrown.
Figure 1 depicts an occluding low sitting over the Great Lakes with an occluding front across south-central Ontario. This front likely played a role in storm development, intensification and ultimately this tornado.

According to Environment and Climate Change Canada (2018), an F0 tornado touched down at 12:00 pm EDT near Caledon, ON. The tornado travelled for 1.5 km and the width of the tornado was not documented by ECCC. The tornado caused no injuries, fatalities or property damage.
Sources
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 18Z Fri Jul 5 1991. Retrieved from: https://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php
Environment and Climate Change Canada Data. (2018). Canadian National Tornado Database: Verified Events (1980-2009) – Public. Retrieved from: http://donnees.ec.gc.ca/data/weather/products/canadian-national-tornado-database-verified-events-1980-2009-public/