Climate of Canberra Area
Canberra, ACT has a relatively dry, continental climate with warm to hot summers and cool to cold winters (at least for Australian standards). Records are based on data from Canberra Airport, which opened in March 1939.
As with the rest of Australia, the climate of Canberra is strongly influenced by a band of high pressure systems located around the globe at about 30-40S, known as the sub-tropical ridge. As this region moves north and south with the sun, so there are different influences on the climate.
During the summer, the sub tropical ridge is located over southern Australia resulting in warm to hot conditions with winds generally from the east through to the northwest.
During winter this ridge is located across northern Australia allowing the westerly winds and associated cold fronts to extend over southern Australia with colder conditions.
The average annual rainfall is 629 mm with an average of 108 rain days per year. Rainfall is reasonably evenly distributed throughout the year with the wettest month being October (65.3 mm) and the driest being June (39.6 mm).
Rainfall tends to be influenced by cold fronts during the winter 6 months and thunderstorms activity during the summer 6 months. Overall autumn tends to be the most stable period for weather. While rainfall in most years is reasonably reliable, drier than average years are closely related to ENSO events in the Pacific Ocean and all significant droughts have occurred in El Nino years. These years also tend to be significant fire seasons as well.
Rainfall across the ACT varies considerably, with much higher rainfall occurring in the ranges to the west of the city and less rainfall to the east. During winter, the ranges tend to act as a barrier, and the city itself is in a relative rain shadow.
Snow at Canberra Airport is actually quite rare, and there may only be 1 to 2 recordings of snow on an annual basis, and most of the time the snow melts very quickly. Snow tends to fall on the ranges to the west, and during winter this snow cover can be readily visible from the city.
January is the hottest month with a mean daily maximum temperature of 27.7°C and an average of 10 days of 30 °C or more with 2 days of 35°C or more. However, because of both its inland location and its elevation (around 580m AMSL) conditions tend to cool overnight and the mean daily minimum temperature in January is 13.0 °C. Canberra tends to get cooler easterly winds penetrating from the coast during many summer evenings which can sometimes bring cloud in with the moister air.
With the warm to hot conditions during summer and the effects of the nearby ranges, there is a distinct thunderstorm season during these months and there are an average of 19 thunderstorm days between October and March compared to an annual average of 23 days.
By contrast winters are cool to cold with generally westerly winds. However winter is also a time when Canberra can experience clear, sunny days with light winds and a considerable number of frosts can occur. The mean daily maximum for July, the coldest month, is 11.2 °C while the mean daily minimum is −0.2 °C. Overall there is an average of 99 frosts for the year with an average of 95 frosts occurring between April and October with an average of 58 of these frosts occurring during the winter. Winter is also a period of considerable fog activity. There is an average of 44 fogs per year in Canberra with an average of 36 fogs occurring between April and September.
The highest recorded maximum temperature was 42.2 °C on February 1 st 1968 followed closely by 41.4 °C on the previous day (31 st January 1968). The lowest recorded minimum temperature was −10.0 °C on 11 th July 1971.
Average annual evaporation in Canberra is 1677 mm, however this can range from around 8 mm/day in summer to as low as 1-2 mm/day in winter.
Canberra is also very sunny, with mean daily sunshine of 7.6 hours/day. In summer mean daily sunshine is around 9 hours/day dropping to around 5-6 hours/day in winter.
Relative humidity tends to be lower in Canberra than near the coast due to its inland location, so even though it tends to be warm to hot in summer, the relative humidity at 3 pm in summer is only around 37-40%.
Canberra generally is not very windy with, on average, 25 days of strong winds a year. Late Winter/Spring tends to be the windiest time with just over half of these days (13 days) occurring in the 4 months between August and November.