Summer in Sydney
Sydney Weather in December
On average, Sydney sees a top of 26°C and an overnight low of 18°C in December, with around 11 rain days and 80mm of total rainfall. UV is typically extreme, 10-12.
26°C
18°C
80mm
11
What December is like in Sydney
December marks the start of proper summer heat. Sydney's legendary outdoor Christmas culture — from Bondi Beach to the Harbour Bridge — plays out under long, warm days with sunset after 8pm. Temperatures frequently hit the high 20s to low 30s, with western suburbs regularly exceeding 35°C. Afternoon sea breezes are essential for cooling the coast. Thunderstorm activity is well established, and the UV is extreme — December's long daylight and high sun angle produce some of the year's most intense UV readings.
These figures are long-term averages, not a forecast — for today's actual conditions and the week ahead, check the live Sydney weather forecast. Averages are useful for planning travel, events or what to pack, but any single December can run warmer, cooler, wetter or drier than the long-term normal.