Sydney weather in September
Sydney averages 21°C by day and 11°C at night in September, with the sea at 19°C and 8 days with at least 1 mm of rain. It warms up by about 2°C into October.
Day
21°C
Night
11°C
Sea
19°C
Rainy days
8
Flight from London
20½h
What September feels like
September is warm in Sydney: T-shirt days, a light layer for evenings.
The sea is 19°C: refreshing, and chilly for most people after a few minutes.
Expect some rain: about 8 days with at least 1 mm.
Of the 48 sun destinations we track, Sydney is the #47 warmest in September.
Want it warmer in September?
These are hotter than Sydney this month for at most an hour and a half more flying:
Sydney weather by month
September is highlighted. Compare with August and October, or see the full year in Sydney.
Sydney in September: quick answers
Is Sydney hot in September?
September is warm in Sydney: T-shirt days, a light layer for evenings. Average highs are 21°C and lows 11°C.
Can you swim in Sydney in September?
The sea is 19°C: refreshing, and chilly for most people after a few minutes.
Does it rain in Sydney in September?
Expect some rain: about 8 days with at least 1 mm.
What is the warmest month in Sydney?
January, at an average high of 27°C. The coolest is June at 17°C.
How long is the flight to Sydney from the UK?
About 20½h direct from London, estimated from the 17,016 km distance. Check your airline for exact times.
Still choosing? See where is hot in September for every destination ranked by temperature, sea and flight time.
How we measured this
Averages of every day in September from 2016 to 2025, from the Open-Meteo historical weather archive (ECMWF ERA5 reanalysis). Sea temperature is the 2023 to 2025 average from the Open-Meteo marine archive. A rainy day has at least 1 mm of rain. Reanalysis describes an area about 25 km across, so sheltered resorts can run a degree or two warmer. Flight time is a distance-based estimate from London Heathrow.
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