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Sydney heading towards 40°C for first time since 2023

It’s an oppressively hot and humid Tuesday in Sydney, with the mercury heading towards 40°C or higher across virtually the whole of the Sydney basin.

For the city's official weather station at Observatory Hill – located near the southern pylon of the Sydney Harbour Bridge on the fringe of the CBD – this could be the first 40-degree day since 2023.

Because of its harbourside location, the sea breeze at Observatory Hill often restricts temps to the 30s while the western suburbs bake in the low 40s. But today is one of those rare citywide scorchers.

• Sydney’s last 40-degree day was December 9, 2023, when it reached exactly 40°C (Penrith in the city’s outer west reached 43.9°C that day).
• In the 2024/25 summer to date, the hottest day at Observatory Hill was 37.4°C on December 27 while the hottest this January (before today) was just 31.7°C on January 6.
• By contrast, Penrith has already exceeded 39°C five times this summer with a hottest temp of 41.6°C on December 17.

While Penrith is likely to slightly exceed the city and reach 42°C today, as mentioned, the uncomfortable conditions are spreading right across the city, from the foot of the Blue Mountains to the coast, with the mercury already reaching 33.6°C at Observatory Hill before 11am.

At 1:34pm, the temperature reached a sizzling 42.5°C at Sydney Airport on the shores of Botany Bay – emphasising just how hot it is in Sydney's east as well as the west, where numerous locations had topped 41°C by 1:30pm.

Southerly buster expected to arrive over Sydney around 3pm, with temperatures beforehand topping 40 °C. pic.twitter.com/U9fbIhh7yG

— Andrew Miskelly (@andrewmiskelly) January 27, 2025

Whether Sydney's maximum edges over the 40-degree mark or not, the day's high temp should occur relatively early in the afternoon, as northwesterly winds win the battle against the sea breeze and push a wave of heat eastwards.

The good news is that a southerly change is on its way. The change should arrive in the mid-to-late afternoon, possibly accompanied by a storm which may be severe.

Before and after #Sydneystorm #shelfcloud #Arcus pic.twitter.com/vcWw3jc8ES

— Tyson Millar (@TysonMillar) January 27, 2025

Storms lashed Sydney on Monday evening, with rapid downpours of 10 to 25mm in most suburbs and spectacular cloud and lightning displays.

Often, such storms herald the arrival of a cooler airmass but that was not the case on Monday. However that cooler air is definitely roaring up the NSW coast today, and will provide relief as far north as the NSW Mid North Coast by Tuesday evening.

Image: Monday’s NSW rainfall was very much concentrated in the Sydney region, thanks to storms which arrived at twilight. Source: BoM.

Sydney will be cooler for the rest of the week from Wednesday onwards with tops in the mid-20s and the chance of showers in a persistent southeasterly wind flow.

Image: 48-Hour Graph on the Weatherzone app for Penrith, NSW, as at 12:20pm AEDT on January 28, 2025.