Ireland will experience a mini Indian summer on Wednesday with highs of 22 degrees.
The extraordinarily warm conditions for the end of September are being caused by tropical air moving up from the Azores. Highs of 19 degrees are being experienced on Tuesday.
Temperatures on Wednesday will be nine degrees above the September norm of 13 degrees.
The highest temperatures will be in the midland and east where there will be sunshine.
Across the western half of the country temperatures will still be higher than normal for the time of year with highs of 18 or 19 degrees though it will be cooler because of cloud cover.
The warm weather will be a one day wonder as temperatures will return to a more normal 15 or 16 degrees on Thursday.
The forecast for the coming days is for a mixture of sunshine and showers.
It is likely that it will remain changeable next weekend with a mix of showery periods and dry bright spells on Saturday for the All-Ireland final replay, and possibly a spell of wet and windy weather on Sunday.
Temperatures will be between 10 and 15 degrees in the afternoon, slightly below normal for early October.