Red algae blooms in New South Wales are warning beachgoers to avoid water due to irritation, following extreme heat.

Beachgoers in New South Wales' Hunter region, including Lake Macquarie, Newcastle, and the Central Coast, are warned to avoid water activities due to red algae blooms of Noctiluca scintillans, or "red tide," which can cause skin and eye irritation. The algae, visible as reddish-pink patches and glowing at night, has been detected at multiple beaches, including Blacksmiths Beach and Shelly Beach, with authorities cautioning that blooms may shift with wind and tide. The alert follows a severe heatwave with temperatures reaching up to 41°C inland and 39°C in coastal areas, accelerating seaweed decomposition and odors. A cool change is expected from Sunday, bringing possible showers and thunderstorms.