Motorists warned to take caution as yellow weather warning in effect
Forecasters have issued a yellow weather alert - as the country braces itself for a weekend of torrential wind and rain.
Gardai have warned motorists to "drive safely and only travel if needed" in the areas worst affected.
Winds in some parts of the country could reach up to 90kmh. The dramatic weather shift marks the end of the late summer temperatures of recent days.
"Intense rainfall" is forecast, and there is a warning that road traffic conditions in some parts of the country will be hazardous.
Southern and western coastal counties will be hardest hit. Rainfall in these parts could be as much as 90mm today and tomorrow.
It is estimated over half the month's average rain will fall this weekend.
The average rainfall in Dublin for October was as low as 79mm - as the capital basked in bouts of autumnal sunshine.
However, the country's second city had a wetter month all round, with the figure for Cork up to 138mm.
"There will be very intense rain and heavy showers throughout the country - with southern and western counties most affected.And obviously with the high winds and rain there will be an issue with fallen trees," said a Met Eireann spokesman.
There have also been warnings that flooding will hit some areas with the highest rainfall.
ESB crews and other emergency services are on high alert should the threat to power supplies escalate. South and south-easterly winds will reach 40kmh-60kmh in most places, with the figure up to 90kmh in the south-west.
The showery rain will spread eastward on Sunday morning, with strong blustery gales forecast.
Overall temperatures will become less mild, dropping to between 13C to 15C.
The showers will be less frequent by tomorrow night but although clear spells will develop, conditions will continue to remain windy.
On Monday the showers will continue in western counties, although eastern parts of the country will become drier and brighter.
However, conditions will still remain very blustery, and the strong westerly winds will continue.
Heavy rain, with the possibility of it getting "very heavy", according to Met Eireann, will spread eastwards to all parts of the country overnight. However, for most areas this will clear to showers before morning.
Temperatures will get much colder on Tuesday, and with strong north-westerly winds, there is a renewed possibility of gales.
Northern counties will be hit by heavy showers but the rest of the country should be dry and bright most of the time.
The outlook for Wednesday is that conditions will generally improve to "dry and bright and less windy".
Meanwhile, Bermuda is set to be hit by the most powerful Atlantic hurricane for some years.
Experts say the residue of the hurricane could herald a spell of more wet and windy conditions but it's still too early to gauge the likely severity of this weather change.