Waters off a popular Hobart beach will remain closed to swimmers over the weekend.

Swimmers have been advised to avoid Long Beach at Sandy Bay and waters off nearby Blinking Billy Point, due to a sewage spill.

The spill was caused by a pump station failure during a power outage.

The Environmental Protection Agency was advised of the incident on Wednesday morning.

Hobart City Council has erected signs advising people not to swim in the immediate area.

The signs will remain in place over the weekend while the council awaits the results of laboratory testing.

Hobart is expecting temperatures in the mid-20s over the next two days.