Following an extremely hot pair of days, the nation's capital just registered its highest minimum temperature since official records began here in 1939.

In the 24 hours to 9am on Sunday, the mercury only dipped to 26.7 degrees at around 4am.

This significantly exceeds the previous record of 26.0 degrees set in both November 1946 and March 1983, set at one of the Canberra Aiport comparison sites. It's worth noting that another weather station at the now-closed Acton site, located near Yarralumla Bay, recorded a minimum temperature of 27.2 degrees on January 14th in 1939. However, this site is nearly 10km away from Canberra Airport.

Canberra's 26.7 degree minimum is quite an impressive feat, especially given that the airport site is almost 600m above sea level and around 100km away from the coast.

Climatologically speaking, inland and elevated locations cool more efficiently once the sun goes down, when compared to low-lying coastal areas.

This is because the air tends to be drier further inland from the coast and higher up in the atmosphere - when atmospheric moisture (in the form of water vapour) is high, it slows the rate of nocturnal cooling.

With the above in mind, yesterday’s record breaking overnight heat can be blamed primarily on the overriding hot and humid airmass, brought down from the tropics.