The Met Office on Saturday issued a yellow weather warning over high temperatures on Sunday, which are expected to hit a peak between 11am and 4pm.
According to the warning, the temperature inland is expected to reach 40C.
Weather services have reported that an unseasonably warm air mass is affecting the region, with temperatures ranging approximately 9C above what is considered normal for the season, in both inland and mountainous and semi-mountainous areas.
A gradual drop in temperature is expected to take place at the beginning of next week, which will gradually fluctuate to more normal levels for the season.
Moreover, there is some chance of rain, primarily towards the middle of the week.