How hot does it need to be to trigger a heat warning?

Despite a weekend with temperatures over 30 degrees Celsius, a heat warning was not declared in Waterloo Region.

The Saturday and Sunday weather across Southwestern Ontario came two weeks out from the official start of summer.

“The criteria [for a heat warning] changes across Canada,” said Frank Seglenieks, weather station coordinator for the University of Waterloo. “Cities like Windsor, Hamiltion, and Toronto all met that heat criteria.

“For our area [of Waterloo Region], it’s two days in a row where the temperatures forecasted go to 31 degrees or higher, and the nighttime temperatures are 20 degrees or higher.”

The humidex value, which combines the actual temperature and humidity into one number, climbed into the mid to upper 30’s all weekend in Waterloo-Wellington, but the area still missed out on a heat warning by just one or two degrees.

The heat has also caused increasing ground-level ozone concentrations in the region, meaning there are high levels of air pollution, which then prompts a special air quality statement.

People with cardiovascular or lung diseases are at an increased risk in this state.

According to Environment Canada, the warning signs for illness due to heat or poor air quality are: dizziness or fainting, nausea, vomiting, headache, and sleepiness or temper tantrums in children.

Anyone who sees someone out in the heat who stops sweating, seems confused, or loses consciousness is asked to call 911.

Temperatures are forecasted to be in the mid to upper 20s throughout the week in Waterloo Region.

Environment Canada says they key to beating the heat is to be prepared with things like sun protection, taking breaks, and staying hydrated.