Temperatures are set to plummet as cold air replaces the warm and sunny conditions that have been around for the last fortnight.
Temperatures reached a high for the season at 19 degrees in Newport, Co Mayo, on Sunday.
The fine weather will continue into Tuesday but there will be an abrupt change from Wednesday with the prospect of snow on higher ground in the northern half of the country.
"It will feel like quite a shock after the lovely, warm weather we have been having," said Met Éireann forecaster Emer Flood.
Ms Flood said the dramatic change in temperatures will be the result of cold air moving down from the Arctic and replacing the warmer tropical air and the high pressure which has brought summer-like weather to most of Ireland.
Highs of between 16 and 18 degrees last week will change to 5 to 9 degrees later in the week. Temperatures at night will fall to between zero and minus 3 degrees.
Frost will have significant impact on young crops that have just been planted, she warned. Any snow that falls, though, will be short-lived in duration.
There are indications of a slight rise in temperature over the weekend to between 8 and 11 degrees.
It will turn milder next week and more unsettled with rain and showers.