Two new weather alerts were issued on Monday afternoon, an orange warning for the higher mountains and a yellow for inland regions due to high temperatures.
Both warnings will be in effect from 9pm on Monday until 6pm Tuesday evening, the met office said.
The risk of forest fires is red all day on Tuesday.
The orange warning states that the minimum temperature in the higher mountains was not expected to fall below 25C, while the maximum is expected to rise to around 35C.
The yellow warning states that the minimum temperature inland was not expected to fall below 26C on Monday night while day temperatures tomorrow would reach 42C.
The forestry department said that due to the expected mass influx of people on the August 15 holiday, the risk of fire was higher, and they would remain on red alert.
The public is strongly urged to exercise extreme caution in forest areas by completely avoiding actions and activities likely to cause a fire.
Lighting a fire without a permit is prohibited and it constitutes an offence punishable by imprisonment of up to 10 years or a fine of up to €50,000 or both.
In case someone notices smoke or fire, they are asked to call 1407 (forestry department) or 112 (fire service) immediately.