The met off on Sunday afternoon issued a red alert for temperatures to hit 44C inland on Monday.
The warning is in effect from 1pm to 5pm.
On Sunday temperatures rose to 43C inland with an orange warning in effect for the same time period.
Temperatures are expected to remain significantly above the seasonal average until Wednesday when they will gradually drop.
The forestry department also issued a red alert for Monday due to the high risk of fire.
It appealed to the public to be especially careful during excursions, and to the agricultural and industrial sectors in the use of tools that could spark a fire.
Anyone who spots smoke or fire should call 1407 (Forest Department) or 112 (Fire Department) immediately.