The mercury hit 26 degrees in Dublin yesterday in what was a “phenomenal” temperature for September but the tropical weather will not last long according to forecasters.
While Monday's balmy conditions did not quite outstrip the highest recorded September value of 29 degrees set in Kildare in 1906, it was still a good deal warmer than the average high of around 17 degrees usually expected for the month.
"We had some very warm conditions yesterday. In Dublin it actually reached 26 degrees in the Phoenix Park which is a phenomenal temperature for September," said Gerry Murphy of Met Éireann.
“Other parts of the country were certainly not as warm. Dublin was the warmest part of the country, but you still had 23.4 in the midlands and 25.6 in Carlow which is close to the 26 mark.”
The warm conditions were caused by heavy, humid air coming up from the tropics, but this is expected to subside later in the week when more changeable conditions will take hold.
"We're under the influence of very warm tropical air at the moment which has been feeding up mainly from the continent over the last few days. Even in Spain at the moment it's up in the high 30s, the circulation is such that it's feeding up very warm air towards us and very humid air as well," said Mr Murphy.
Today will be hot again with temperatures reaching 24 degrees in Dublin and slightly cooler elsewhere.
Some rain will appear along the west coast where temperatures will be restricted to the high teens, and tomorrow presents a similar picture before a band of persistent rain helps to usher in some cooler weather on Thursday.
The weekend outlook will alternate between dry spells and heavy rain, with Friday and Sunday expected to bring the worst of the downpours.