Perth's Climate
There is very little rainfall in summer. Rainfall comes mainly in winter although, even in winter, Perth usually enjoys plenty of pleasantly warm sunshine.
Perth can be windy, especially in the hotter months. The "fremantle doctor" is a sea breeze that offers relief from Perth's high summer heat. It can also blow sand around and, when particularly strong, can be rather hazardous for people on the beach.
Inland suburbs of Perth can be significantly hotter than coastal suburbs. Average daily maximum temperatures at Perth Airport - around 10 miles inland - reach around 32 degrees Centigrade in summer. On the coast, at Fremantle, the average highs are around 4 or 5 degrees lower.
On a few days each summer, temperatures rise above 40 degrees Celsius. By any stretch of the imagination, these are extreme temperatures. The best thing you can do on these days is stay at home with your air-conditioning on maximum.
Sea temperatures around Perth are very pleasant.
The climate of Perth, like many Australian locations, is getting drier. Water levels behind the dams that supply the city were steadily falling. A desalination plant at Kwinana, 25 km south of Perth, completed in 2006, now supplies around 10 percent of Perth's water. This is planned to increase to 17 percent. The plant is powered by a wind-farm and is the world's largest renewables-powered desalination plant.
Perth
| Month | Av. Daily Maximum Temp. (OC)  |
Av. Daily Minimum Temp. (OC)  |
Av. Days with Rainfall  |
Av. Afternoon Humidity |
Av. hours Sunshine (per day)  |
| Jan. | 30 | 18 | 3 | 45 | 11 |
| Feb. | 30 | 17 | 3 | 45 | 10 |
| Mar. | 27 | 16 | 5 | 45 | 9 |
| Apr. | 24 | 14 | 8 | 50 | 7 |
| May | 21 | 12 | 15 | 60 | 6 |
| Jun. | 19 | 10 | 17 | 65 | 5 |
| Jul. | 17 | 9 | 18 | 65 | 5 |
| Aug. | 18 | 10 | 19 | 60 | 6 |
| Sep. | 19 | 10 | 15 | 60 | 7 |
| Oct. | 21 | 12 | 12 | 55 | 9 |
| Nov. | 24 | 14 | 6 | 50 | 10 |
| Dec. | 28 | 17 | 5 | 45 | 11 |