But further afield, their regional counterparts sweltered as the mercury tipped 38C.

Melbourne reached a high of 23.9C on Tuesday, not quite peaking at the 26C forecasted.

However in northwest Victoria, Walpeup reached a scorching 38.7C, while Mildura residents dealt with a high of 38C.

"Today we've had sunny conditions across the state, some cloud about the coastal areas," Bureau of Meteorology senior forecaster Beren Bradshaw told AAP on Tuesday.

"So far today Melbourne has reached 23.9C. That's due to the winds. The winds are in a southerly direction so anywhere close to the coast will get a breeze."

She said Boxing Day was expected to be sunny and dry across the state, with the heat continuing to surge before dropping off ahead of the weekend.

The hot trend will particularly hit the northwest parts of the state, while Melburnians won't suffer as much.

"For the remainder of the week, that northwest inland part of the state will be quite hot - so they'll be looking at temperatures in the 40s for the next few days," Ms Bradshaw says.

"(But) Melbourne will be 26C on Wednesday, 35 on Thursday, then it will slowly drop into the low 30s and high 20s after that leading into the weekend."

Australian Associated Press