A burst of spring warmth sweeping over eastern NSW will deliver Sydney’s first 30°C day of the season this weekend.

It has been six months since Sydney last reached 30°C but that run is likely to come to an end on Saturday, with the mercury predicted to hit 31°C in the Harbour City.

A stream of northwesterly winds will carry warm air over eastern NSW between Friday and Sunday, causing temperatures to climb more than 5°C above average for this time of year.

Image: Modelled air temperature and wind over eastern NSW on Saturday afternoon.

Sydney is forecast to reach 29°C on Friday and 31°C on Saturday, while Sunday’s warmth will be capped at the mid-twenties due to a southerly change in the morning.

Saturday’s 31°C would be Sydney’s warmest day since mid-March and its first day over 30°C so far this season. Days this warm are fairly rare this early in spring, with the city only averaging one 30°C day every two years during September.

Image: Sydney’s hourly forecast on the Weatherzone app, showing temperatures reaching the low thirties early in Saturday afternoon.

Saturday’s warm weather will undoubtedly cause many Sydneysiders to flock to beaches and harbour swimming spots to enjoy the early-spring warmth. However, anyone getting in the water might get a shock to find water temperatures are still cool at this time of year, hovering around 18 to 19°C along the coast.

Sydney will cool down from Sunday afternoon into the start of next week, before temperatures rise back to the high twenties once again on Tuesday.