ACT braces for another 40C scorcher

The ACT is bracing for a second consecutive 40 degree day after sweating through its hottest day in 12 months.

The thermometer peaked at 40.2 degrees on Wednesday afternoon, a temperature not reached since January 18 last year.

And Thursday is predicted to be just as hot, with the Bureau of Meteorology predicating the heat to reach a high of 40 degrees.

ACT Emergency Services Agency Commissioner Dominic Lane declared the territory would be placed under a total fire ban on Thursday until midnight, with the fire danger currently being rated "severe".

Fire services raced to mop up a grass fire near the Tuggeranong Parkway in Molonglo overnight.

Temperatures will remain in the high 30s in Canberra until Sunday when light showers are forecast to break the heat.