The mild weather which has made this one of the warmest autumns on record is due to end on Thursday.
A series of tropical maritime air masses from the south-west has brought temperatures more akin to the middle of summer.
A high of 19.2 degrees was recorded at Carlow on Sunday and temperatures were up to 19 degrees in the Phoenix Park in Dublin on Monday morning.
This is between five and seven degrees higher than the average for this time of year.
Currently every weather station in the State is showing temperatures well above the long term average for October. Phoenix Park is currently recording a temperature of 12.5 degrees for October, the average being 10.9 degrees.
Oak Park in Co Carlow’s average temperature for the month at 12.1 degrees is two degrees higher than normal and in Cork it is 11.8 degrees, 1.5 degrees higher than normal.
Met Éireann forecaster Emer Flood said there has been a series of tropical air flows over Ireland during the autumn. The normal weather pattern is for cooler air masses from the north to be over Ireland during the autumn bringing rain and lower temperatures.
Normal service will resume on Thursday as Atlantic low fronts bring fresh, blustery weather and highs of only 12 degrees.
The unsettled weather will continue into the weekend with wet, breezy conditions at times as showers and spells of rain spread from the Atlantic.
The extraordinarily mild October follows on from one of the warmest September on record with temperatures well above normal everywhere.
Eleven weather stations in the Republic had a record-breaking month, while temperatures in Northern Ireland were equal to the previous record from 15 years ago.
The 27.9 degrees recorded at Shannon Airport on September 7th was the highest temperature reported at the station in September there since records began and nine other stations had their record temperatures for that month on that day.
All mean air temperatures across the country were above their long-term average (LTA) for the month of September and are likely to be similarly above average for October.
Deviations from mean air temperatures ranged from 1.1 degree (14.3 degree mean temperature) at Malin Head, Co Donegal to 2.3 degrees (15.5 degrees mean temperature) at Phoenix Park in Dublin.
Mean temperatures for the month ranged from 13.6 degrees (1.6 degrees above its LTA) at Knock Airport, Co Mayo to 15.7 degrees at both Sherkin Island, Co Cork (1.4 degrees above its LTA) and Shannon Airport (1.5 degrees above its LTA).
