Dangerous heat and humidity is expected to arrive in eastern Ontario Sunday afternoon, with Environment Canada issuing heat warnings across the region and forecasting potential record-breaking highs for the first full week of summer.

The forecast includes highs in some places hitting 36 C, with humidex values up to 45 and overnight lows only dropping down to 25 C.

The heat event is expected to last until Tuesday night, when a cold front is expected to push through the region.

But if that cold front remains further north, the extreme weather could continue into Wednesday, the agency notes.

The warm and humid air mass is also expected to reach western Quebec, with Environment Canada having issued special weather statements for that region as of Saturday afternoon, predicting humidex values between 40 and 45.

Health Canada recommends staying cool and staying hydrated when extreme heat hits.

That can mean everything from drinking lots of water and planning outdoor activities for cooler times, to preparing meals that don't require ovens and keeping nearby air-conditioned spaces in mind if needed.

This is true for yourself and for vulnerable people you know.

Watch for signs of heat exhaustion — like a headache, dizziness or a rapid heartbeat — and get to a cool place where you can drink water. Heat stroke, which includes confusion and very hot or red skin, is a medical emergency requiring a 911 call.

More resources may be available through your municipality. Ottawa, for example, has a map of public and other places to cool off.

Ottawa's record high for both June 23 and 24 is 34.4 C, set in 1921 and 1919, respectively. Its highest humidex on record was 47, reached in 2006 and again in 2018.

Research shows heat waves are becoming increasingly extreme as the climate warms.

Environment Canada has started analyzing weather data and climate model simulations to compare how heat waves have changed between today's climate and the cooler pre-industrial one.