Temperatures of 21C were recorded in counties Roscommon, Sligo and Mayo, Met Éireann has said.
It is the highest temperature recorded so far this year, and the good weather is expected to continue this weekend.
The meteorological service said that temperatures could reach 21C again in parts of the country over the weekend, with high pressure dominating and continuing into next week.
However, a few showers are due to move up over Leinster and Ulster tomorrow morning but they will clear by noon.
Tomorrow will be mainly dry with a fair amount of cloud and some sunny spells.
Highest temperatures will be between 13C and 16C over the western half of Ireland and between 17C and 21C in the east.
Watch: Sunshine lifting the mood in Dublin
Met Éireann said Sunday will also be mainly dry, with a fair amount of cloud and some sunny spells.
It said a few showers may develop in Leinster and Ulster during the afternoon and evening. Sunday's temperatures will be between 14C and 18C.
Last year, Athenry, Co Galway, recorded the highest maximum temperature on record for April, with a mercury hit of 25.9C on 30 April.
Temperatures 2C or 3C above normal, says meteorologist
Meteorologist at Met Éireann Matthew Martin said that the high temperatures were "not too unusual" for this time of year, but added temperatures are expected to be around 2C or 3C above normal over the next seven days.
"It is not going to be all clear for the weekend, we do have some showers moving up, particularly in the south and west tonight.
"Otherwise, the weekend is looking mostly dry, a mix of cloud and sunny spells with temperatures getting up to between 15 and 21C," he said.
Speaking on RTÉ's Today with David McCullagh, he said there is a lot of uncertainty in the forecast from around Thursday and into the May bank holiday.
However, Mr Martin added that at the moment the good weather is expected to last until the middle of next week or later next week.
"There is certainly still some hope that it’ll hang on through the bank holiday weekend," he said.
