WEATHER · CLIMATE NORMALS · 1991–2020
Perth Climate — Averages by Month
What the weather in Perth, AUaverages across a standard 30-year period. Each month's figure is the 1991–2020 mean temperature and total rainfall from the ERA5 reanalysis — the long-run normal a place settles around, not a forecast for any particular day.
Month-by-month normals
| Month | Avg temperature | Avg rainfall |
|---|---|---|
| January | 23.8 °C | 18.6 mm |
| February | 24.1 °C · warmest | 17.5 mm |
| March | 22.6 °C | 20.0 mm |
| April | 19.9 °C | 27.0 mm |
| May | 16.9 °C | 72.2 mm |
| June | 14.8 °C | 105.5 mm |
| July | 13.9 °C · coldest | 109.3 mm · wettest |
| August | 14.2 °C | 96.1 mm |
| September | 15.1 °C | 61.2 mm |
| October | 17.2 °C | 32.0 mm |
| November | 19.7 °C | 21.6 mm |
| December | 22.1 °C | 10.9 mm |
How to read these numbers
These are reanalysis normals, not readings from a single weather station. They come from the ERA5 0.25° (~25 km) global reanalysis grid, sampled at the grid cell nearest Perth — centred at 32.00°S, 115.75°E. A reanalysis blends observations with a physics model onto an even grid, so a coastal or mountain city's cell can read a little cooler, warmer, wetter or drier than the city centre itself. The month-to-month shape — when it's hot, when it rains — is what these normals capture best.
“Normal” means the 1991–2020 average, the current World Meteorological Organization standard period. A normal is what a place tends toward over decades — any single day, month or year can and will depart from it.