AFTER a hotter than average end to spring, the first few nights of summer will have Canberrans reaching for blankets with lows of 7 and 8 degrees predicted for Monday and Tuesday.
And Sunday's top temperature won't hit 30 degrees, with forecasters now predicting showers and a maximum of 27.
A spokeswoman from the Canberra Field Meteorological Office said it was a return to ''more typical summer weather''.
''We have a trough right across the country and it's producing showers and storms and that should move towards the north-east in the next few days,'' she said.
''So we should get some cooler air coming in behind it.''
But the temperate days won't last long and the ACT Heart Foundation chief executive Tony Stubbs said Canberrans should enjoy the cooler weather while preparing for a long, hot summer.
The Bureau of Meteorology predicts heatwaves and an above-average risk of flooding this December, driven by a weakly returning La Nina and warmer than normal waters in the Indian Ocean.
Mr Stubbs said as the temperature rises, the body tries to counteract the heat by sweating.
''Sweating leads to dehydration, which reduces the volume of blood. This makes the heart pump harder in order to circulate the reduced amount of blood around the body,'' he said.
''For people with heart disease and those who are at high risk of a heart attack, these changes can overwhelm the heart and result in a heart attack.''
He urged Canberrans with heart disease to stay inside and avoid exercise in the hottest part of the day.
''People most at risk are those with a chronic disease, such as heart disease, as well older people, children, people taking certain types of medicines and people engaged in strenuous outdoor activity,'' Mr Stubbs said.