Sydney weather in September
Sydney averages 21°C by day and 11°C at night in September, with the sea at 19°C and about 55 mm of rain in the month. It warms up by about 2°C into October.
Day
21°C
Night
11°C
Sea
19°C
Rain
55 mm
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.
Rain is occasional: about 55 mm in the month.
That is 1°C warmer than an average September day in London.
Of the 56 sun destinations we track, Sydney is the #55 warmest in September.
Going to Sydney in September?
Share the TikToks and Instagram Reels you've saved for Sydney to Dream Trip. It finds the places, pins them on a map and builds your days around them.
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?
Rain is occasional: about 55 mm in the month.
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. Rain is the average monthly total. 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.
Planning Sydney in September?
Save the restaurants, beaches and views you find on TikTok and Instagram for Sydney straight to a map, then let Dream Trip turn them into a day-by-day plan.
