Heat warnings cover much of Alberta with highs near 30 C Wednesday and Thursday

Several more days of heat before a big drop. Jodi Hughes has a look at the five-day forecast from the Sky Watch Weather Centre.

A dominant ridge of high pressure sitting over Alberta has prompted Environment and Climate Change Canada to issue widespread heat warnings, including for the City of Calgary.

Communities along the foothills as well as the southernmost regions are not under this heat warning, including Banff, Lethbridge and Medicine Hat.

The criteria for a heat warning in Alberta for areas north of the southern border include at least two consecutive days of daily highs of (at least) 29 C plus daily lows of (at least) 14 C.

Areas in the southernmost portion of the province – including Pincher Creek, Cardston, Lethbridge and Medicine Hat - have thresholds that are higher (highs of at least 32 C with lows of at least 16 C).

In Calgary, the official daily high and low on Wednesday will likely be just shy of that warning threshold but some communities within the city could certainly achieve those values.

A fast-moving shortwave will likely develop within that ridge on Thursday bringing thunderstorms and strong wind into most of southeastern British Columbia before crossing the Rockies into southern Alberta late Thursday night.

This wind could create some challenges for crews battling wildfires in Alberta.

As of 7:30 a.m. Wednesday, the fire danger relative index across most of Alberta, Saskatchewan and Manitoba was rated as “extreme” or “very high” due to the hot dry conditions.

The fire danger relative index is based on three main criteria: how easy it would be for a wildfire to start, how difficult that wildfire would be to control and the amount of potential damage if said wildfire occurs.

More warm weather will follow that brief period of instability with the daytime highs in Calgary on Friday and Saturday forecast to reach 30 C and 26 C respectively.

An incoming low will dislodge this upper pattern and produce another rapid change on Sunday bringing a risk of rain for at least a couple of days and dropping temperatures by as much as 12 degrees.