The green, orange, red light warning system tells swimmers if the water is suitable for swimming at 36 monitored beaches or if bacterial levels are too high.

The Environment Protection Authority provides the water quality updates on the Beach Report website and via EPA twitter, with reports issued twice a day.

Water conditions in the Bay are often adversely affected by storm events and city runoff flowing into the bay.

Water Minister Lisa Neville said the hot spring and expected long summer meant the beach report had started a month early and would go a month later to April.

"The combination of hot temperatures and more storms meant we think it was a good idea to bring it forward and give the people confidence about the beaches they are swimming at," she said.

She said we can expect a hotter than average and drier than average summer.

"We want to make sure people are across the water quality at our beaches and when you have the storm surges, you end up with more stormwater runoff that can affect the quality of the Bay," she said.

"People can check on this and if they see a red alert to avoid the area during that period of time and to really drill down if you are thinking about it during the orange period," she said.

She said high bacteria times normally clear within 24 hours.

"Don't take any risks with your health and use the system to make really good decisions about the quality of the water at the beaches," she said.

Ms Neville said a new "state of the bay report" would be released next year. She said this might be extended to look at the quality of Victoria's coastal areas and marine environment.

The EPA beach report monitors 36 bay beaches.