Poor air quality as the result of bush fires has forced the cancellation of Wednesday's meeting at Bairnsdale.

After consultation with the Bureau of Meteorology, Racing Victoria stewards abandoned the meeting on Wednesday morning.

Smoke haze from bushfires in East Gippsland and NSW resulted in the air quality deteriorating on Tuesday night.

The forecast it would not improve through Wednesday, making it unsuitable for racing.

Victoria's hot weather brought forward the start of Wednesday's meeting at Caulfield to 11am with a finishing time of 2.40pm to avoid the hottest part of the day.

Racing Victoria on Wednesday also announced that with temperatures in excess of 40 degrees forecast in Melbourne, interim changes have been made for Friday night's The Valley meeting.

The first race has been provisionally pushed back by 30 minutes to 7pm with the final race scheduled for 10.30pm.