Heat wave expected to bring hot, humid temperatures starting Thursday

Another heat wave during an already hot and humid summer in Ottawa could bring scorching conditions starting on Thursday and into the weekend. 

Environment Canada issued a heat warning for Ottawa-Gatineau on Wednesday afternoon, alerting of daytime temperatures reaching 30 to 32 C with humidity making the outside temperature feel like 40 C.

Overnight minimum temperatures will be 19 to 21 degrees. 

"Extreme heat can affect everyone’s health. The health risks are greater for older adults, infants and young children, pregnant people, people with physical and/or mental illnesses, and people with disabilities or mobility issues," Environment Canada's warning says.

"Drink plenty of water regularly, even before you feel thirsty to decrease your risk of dehydration. Thirst is not a good indicator of dehydration."

Environment Canada issues heat warnings when high temperatures or humidity conditions are expected to pose an elevated risk of heat illnesses, such as heat stroke or heat exhaustion.

Five-day forecast

Ottawa saw a soaking from Mother Nature on Wednesday, on the final day of one of the wettest July's over the past 10 years.

Environment Canada's forecast says Ottawa could see 15 to 25 mm of rain before rain ends this afternoon.

Ottawa has already received 150.5 mm of rain in July, including 47.2 mm on July 6 and 32.8 mm on July 24.

Here is a look at the July rainfall totals between 2015 and 2024

•  2024: 150.5 mm
•  2023: 142.4 mm
•  2022: 89 mm
•  2021: 104 mm
•  2020: 54 mm
•  2019: 52.1 mm
•  2018: 180 mm (61 mm on July 25 and 43 mm on July 23)
•  2017: 249 mm (79 mm on July 24, 42.6 mm on July 14 and 42 mm on July 1)
•  2016: 52.7 mm
•  2015: 40.8 mm

The forecast says a few showers will end this afternoon then cloudy with a 60 per cent chance of showers. High 28 C, with the humidex making it feel like 37.

The record for greatest rainfall on July 31 is 37.8 mm, set in 1996.

Partly cloudy tonight with a 60 per cent chance of showers this evening. There is a risk of a thunderstorm. Low 21 C.

Thursday will see a mix of sun and cloud with a 30 per cent chance of showers. High 30 C, with the humidex of 38.

A mix of sun and cloud on Friday. High 30 C.

The outlook for Saturday calls for cloudy with a 30 per cent chance of showers. High 29 C.

Sunday will see a mix of sun and cloud. High 28 C.

The normal temperatures for this time of year are a high of 26 C and a low of 16 C.