Whitby, Ontario is in for a wet and muggy stretch through Wednesday, July 29, with Environment Canada calling for a 60 percent chance of showers and a risk of thunderstorms. The unsettled weather is expected to finally clear out Thursday with sunny skies and a high of 28°C.
As of late Tuesday morning, the Oshawa Executive Airport was already recording cloudy skies at 22.1°C, with humidity at 88 percent and a Humidex value of 30. The forecast for the rest of Tuesday calls for a high of 26°C and a Humidex of 32, with the threat of a thunderstorm lingering into the evening.
Wednesday will bring similar conditions: a mix of sun and cloud, a 60 percent chance of showers, a risk of thunderstorm, and a north wind at 20 km/h. The high is again forecast at 26°C, and the Humidex is expected to reach 31. The UV index will be 8, or very high.
Boaters on Lake Ontario should be aware that a Strong Wind Warning is in effect for Eastern Lake Ontario. Winds are forecast to strengthen to north 20 knots overnight Tuesday, causing waves to build to 1 to 1.5 metres by early Wednesday morning. The lake water temperature near Whitby was measured at 21°C by an Environment Canada buoy.
The Port Whitby Marina, now in its peak summer operating hours from 7:30 a.m. to 7 p.m., notes that its public boat launch can be closed due to weather. Mariners are advised to check conditions before heading out.
Though there is no formal thunderstorm watch or warning as of Tuesday midday, Environment Canada did issue a severe thunderstorm watch for Durham Region on July 21. The Town of Whitby’s Climate Emergency Response Plan, in place since September 2023, identifies thunderstorms, floods, and extreme heat as key local climate risks.
