Subj : Southern Ontario Weather To : All From : Northern Realms Date : Sun Oct 05 2025 15:35:00 FPCN11 CWTO 051930 Forecasts for Southern Ontario and the National Capital Region issued by Environment Canada at 3:30 p.m. EDT Sunday 5 October 2025 for tonight Monday and Monday night. The next scheduled forecast will be issued at 5:00 a.m. EDT Monday. City of Toronto. Tonight..Clear. Low 15. Monday..Sunny. High 28. Humidex 32. UV index 5 or moderate. Monday night..Clear in the evening and after midnight then partly cloudy with 30 percent chance of showers before morning. Risk of a thunderstorm before morning. Low 18. Windsor - Essex - Chatham-Kent. Tonight..Clear. Low 15. Monday..Sunny. High 29. Humidex 34. UV index 6 or high. Monday night..Increasing cloudiness. 60 percent chance of showers overnight with risk of a thunderstorm. Wind becoming southwest 20 km/h after midnight. Low 18. Sarnia - Lambton. Tonight..Clear. Low 15. Monday..Sunny. High 29. Humidex 34. UV index 5 or moderate. Monday night..Increasing cloudiness. 60 percent chance of showers overnight with risk of a thunderstorm. Low 18. Elgin. Tonight..Clear. Low 16. Monday..Sunny. Wind becoming southwest 20 km/h late in the morning. High 27. Humidex 32. UV index 5 or moderate. Monday night..Increasing cloudiness. 60 percent chance of showers overnight with risk of a thunderstorm. Wind becoming southwest 30 km/h after midnight. Low 18. London - Middlesex. Tonight..Clear. Low 15. Monday..Sunny. Wind becoming southwest 20 km/h in the afternoon. High 28. Humidex 32. UV index 5 or moderate. Monday night..Clear. Increasing cloudiness near midnight then 60 percent chance of showers overnight. Risk of a thunderstorm overnight. Wind southwest 20 km/h becoming light in the evening. Low 17. Simcoe - Delhi - Norfolk. Tonight..Clear. Low 12. Monday..Sunny. High 27. Humidex 30. UV index 5 or moderate. Monday night..A few clouds. Increasing cloudiness after midnight then 40 percent chance of showers overnight. Risk of a thunderstorm before morning. Low 17. Dunnville - Caledonia - Haldimand. Tonight..Clear. Low 14. Monday..Sunny. High 26. Humidex 31. UV index 5 or moderate. Monday night..Clear. Increasing cloudiness after midnight. Low 18. Oxford - Brant. Tonight..Clear. Low 14. Monday..Sunny. Wind becoming southwest 20 km/h in the afternoon. High 28. Humidex 33. UV index 5 or moderate. Monday night..Clear. Increasing cloudiness near midnight then 40 percent chance of showers overnight. Risk of a thunderstorm before morning. Wind southwest 20 km/h becoming light in the evening. Wind becoming southwest 30 after midnight. Low 17. Niagara Falls - Welland - Southern Niagara Region. Tonight..Clear. Low 19. Monday..Sunny. High 26. Humidex 31. UV index 5 or moderate. Monday night..Clear. Increasing cloudiness after midnight. Wind becoming southwest 20 km/h near midnight. Low 19. St. Catharines - Grimsby - Northern Niagara Region. Tonight..Clear. Low 16. Monday..Sunny. Wind becoming southwest 20 km/h late in the afternoon. High 27. Humidex 32. UV index 5 or moderate. Monday night..Clear. Increasing cloudiness after midnight. Wind southwest 20 km/h becoming light in the evening. Low 19 with temperature rising to 22 by morning. City of Hamilton. Tonight..Clear. Low 15. Monday..Sunny. High 26. Humidex 31. UV index 5 or moderate. Monday night..Clear in the evening then partly cloudy with 40 percent chance of showers overnight. Risk of a thunderstorm before morning. Low 18. Halton - Peel. Tonight..Clear. Low 15. Monday..Sunny. High 28. Humidex 32. UV index 5 or moderate. Monday night..Clear in the evening and after midnight then partly cloudy with 30 percent chance of showers before morning. Risk of a thunderstorm before morning. Low 18. York - Durham. Tonight..Clear. Low 14. Monday..Sunny. High 28. Humidex 31. UV index 5 or moderate. Monday night..Clear in the evening and after midnight then partly cloudy with 30 percent chance of showers before morning. Risk of a thunderstorm before morning. Low 15. Huron - Perth. Tonight..Clear. Low 15. Monday..Sunny. Becoming a mix of sun and cloud in the afternoon. Wind becoming southwest 20 km/h in the afternoon. High 28. Humidex 31. UV index 5 or moderate. Monday night..Becoming cloudy in the evening. 60 percent chance of showers overnight. Risk of a thunderstorm before morning. Wind southwest 20 km/h becoming light in the evening. Low 16. Kitchener - Cambridge - Region of Waterloo Guelph - Erin - Southern Wellington County. Tonight..Clear. Low 13. Monday..Sunny. Wind becoming southwest 20 km/h in the afternoon. High 28. Humidex 31. UV index 5 or moderate. Monday night..Clear in the evening and after midnight then partly cloudy with 40 percent chance of showers overnight. Risk of a thunderstorm overnight. Wind southwest 20 km/h becoming light near midnight. Low 18. Mount Forest - Arthur - Northern Wellington County. Tonight..Clear. Low 16. Monday..Sunny. Increasing cloudiness late in the afternoon. High 27. Humidex 31. UV index 5 or moderate. Monday night..Partly cloudy. Becoming cloudy after midnight with 40 percent chance of showers overnight. Risk of a thunderstorm overnight. Low 16. Dufferin - Innisfil. Tonight..Clear. Low 16. Monday..Sunny. High 28. Humidex 32. UV index 5 or moderate. Monday night..Clear in the evening and after midnight then partly cloudy with 40 percent chance of showers overnight. Risk of a thunderstorm overnight. Low 16. Saugeen Shores - Kincardine - Southern Bruce County. Tonight..Clear. Wind becoming south 30 km/h this evening. Low 17. Monday..Sunny. Wind southwest 30 km/h. High 26. Humidex 31. UV index 5 or moderate. Monday night..Increasing cloudiness. 30 percent chance of showers late in the evening and after midnight. Showers beginning after midnight. Risk of a thunderstorm overnight. Wind south 20 km/h becoming light near midnight. Low 14. Bruce Peninsula - Sauble Beach - Tobermory. Tonight..Clear. Low 16. Monday..Sunny. High 23. Humidex 28. UV index 5 or moderate. Monday night..Mainly cloudy with 40 percent chance of showers in the evening and after midnight. A few showers beginning after midnight. Risk of thunderstorms late in the evening and after midnight. Low 12. Hanover - Dundalk - Southern Grey County Owen Sound - Blue Mountains - Northern Grey County. Tonight..Clear. Low 17. Monday..Sunny. Wind becoming southwest 20 km/h late in the morning. High 27. Humidex 31. UV index 5 or moderate. Monday night..Increasing cloudiness. 30 percent chance of showers late in the evening and after midnight. Showers beginning after midnight. Risk of a thunderstorm overnight. Low 14. Barrie - Collingwood - Hillsdale. Tonight..Clear. Low 15. Monday..Sunny. High 28. Humidex 31. UV index 5 or moderate. Monday night..Clear in the evening then partly cloudy with 30 percent chance of showers late in the evening and after midnight. Showers beginning after midnight. Risk of a thunderstorm overnight. Low 16. Midland - Coldwater - Orr Lake Orillia - Lagoon City - Washago. Tonight..Partly cloudy. Clearing late this evening. Low 17. Monday..Sunny. High 26. Humidex 31. UV index 5 or moderate. Monday night..Increasing cloudiness. 30 percent chance of showers late in the evening and after midnight. Showers beginning after midnight. Risk of a thunderstorm overnight. Low 15. Belleville - Quinte - Northumberland. Tonight..Clear. Fog patches developing overnight. Low 11. Monday..Sunny. Fog patches dissipating in the morning. High 26. Humidex 30. UV index 5 or moderate. Monday night..Clear. Low 15. Picton - Sandbanks Park Napanee - Consecon. Tonight..Clear. Fog patches developing overnight. Low 11. Monday..Sunny. Fog patches dissipating in the morning. High 26. Humidex 30. UV index 5 or moderate. Monday night..Clear. Low 15. Kingston - Odessa - Frontenac Islands. Tonight..Clear. Fog patches developing overnight. Low 15. Monday..Sunny. Fog patches dissipating in the morning. High 23. Humidex 28. UV index 5 or moderate. Monday night..Clear. Becoming partly cloudy after midnight. Low 16. Lindsay - Southern Kawartha Lakes Fenelon Falls - Balsam Lake Park - Northern Kawartha Lakes. Tonight..Clear. Fog patches developing overnight. Low 13. Monday..Sunny. Fog patches dissipating in the morning. High 27. Humidex 32. UV index 5 or moderate. Monday night..Partly cloudy. 30 percent chance of showers before morning. Low 18. Peterborough City - Lakefield - Southern Peterborough County Apsley - Woodview - Northern Peterborough County. Tonight..Clear. Fog patches developing overnight. Low 11. Monday..Sunny. Fog patches dissipating in the morning. High 27. Humidex 31. UV index 5 or moderate. Monday night..Partly cloudy. 30 percent chance of showers before morning. Low 17. Stirling - Tweed - South Frontenac. Tonight..Clear. Fog patches developing overnight. Low 11. Monday..Sunny. Fog patches dissipating in the morning. High 27. Humidex 31. UV index 5 or moderate. Monday night..A few clouds. Low 17. Bancroft - Bon Echo Park. Tonight..Clear. Low 10. Monday..Sunny. High 27. Humidex 30. UV index 5 or moderate. Monday night..Partly cloudy. 40 percent chance of showers overnight. Risk of a thunderstorm before morning. Low 15. Brockville - Leeds and Grenville. Tonight..Clear. Low 15. Monday..Sunny. High 28. Humidex 31. UV index 5 or moderate. Monday night..Clear. Becoming partly cloudy after midnight. Low 17. City of Ottawa. Tonight..Clear. Low 14. Monday..Sunny. High 30. Humidex 33. UV index 5 or moderate. Monday night..Clear. Low 17. Gatineau. Tonight..Clear. Low 11. Monday..Sunny. High 30. Humidex 33. UV index 5 or moderate. Monday night..Clear. Low 15. Prescott and Russell. Tonight..Clear. Low 16. Monday..Sunny. High 28. Humidex 30. UV index 5 or moderate. Monday night..Clear. Low 19. Cornwall - Morrisburg. Tonight..Clear. Low 14. Monday..Sunny. High 28. Humidex 31. UV index 5 or moderate. Monday night..Clear. Low 16. Smiths Falls - Lanark - Sharbot Lake. Tonight..Clear. Low 12. Monday..Sunny. High 27. Humidex 30. UV index 5 or moderate. Monday night..Clear. Low 17. Port Carling - Port Severn Bracebridge - Gravenhurst. Tonight..A few clouds. Low 15. Monday..Sunny. High 27. Humidex 30. UV index 5 or moderate. Monday night..Increasing cloudiness. 40 percent chance of showers in the evening. A few showers beginning near midnight. Risk of a thunderstorm overnight. Low 16. Town of Parry Sound - Rosseau - Killbear Park Huntsville - Baysville. Tonight..Clear. Low 17. Monday..Sunny. High 25. Humidex 30. UV index 5 or moderate. Monday night..Becoming cloudy in the evening with 40 percent chance of showers later in the evening. A few showers beginning near midnight. Risk of a thunderstorm overnight. Low 14. Haliburton. Tonight..Clear. Low 15. Monday..Sunny. Becoming a mix of sun and cloud in the afternoon. High 25. Humidex 29. UV index 5 or moderate. Monday night..Partly cloudy. Becoming cloudy after midnight with 40 percent chance of showers overnight. Risk of a thunderstorm before morning. Low 15. Renfrew - Pembroke - Barry's Bay. Tonight..Clear. Low 17. Monday..Sunny. High 28. Humidex 30. UV index 5 or moderate. Monday night..Clear. Increasing cloudiness after midnight then 40 percent chance of showers overnight. Risk of a thunderstorm before morning. Low 17. Algonquin. Tonight..Clear. Low 12. Monday..Sunny. High 26. Humidex 29. UV index 5 or moderate. Monday night..Increasing cloudiness. 30 percent chance of showers late in the evening and after midnight. A few showers beginning overnight. Risk of a thunderstorm overnight. Low 14. Burk's Falls - Bayfield Inlet. Tonight..Partly cloudy. Becoming clear near midnight. Low 17. Monday..Sunny. High 25. Humidex 29. UV index 5 or moderate. Monday night..Increasing cloudiness. 40 percent chance of showers in the evening. A few showers beginning near midnight. Risk of a thunderstorm overnight. Low 12. End $$$$^^ --- up 3 days, 12 hours, 27 minutes * Origin: Northern Realms (1:229/664) .