The Environmental Protection Department has rated water quality at 24 beaches 'good' for this weekend, with nine more 'fair'.

Compared with last week, Pui O Beach and Stanley Main Beach have been upgraded from fair to good, and Silverstrand Beach has been downgraded from good to fair.

Seven gazetted beaches - Anglers', Approach, Ting Kau, Casam, Gemini, Hoi Mei Wan and Lido - are closed to swimmers year-round because of poor water quality.

Many beaches are likely to be more polluted than their grades suggest during and after heavy rain. Bathers should avoid swimming at beaches for up to three days after a storm or heavy rainfall.