A status Yellow rain warning remains in place for Dublin and Wicklow until 10am on Wednesday.
But the brunt of the storm is expected to hit tomorrow, when between 40mm and 60mm is expected to fall in just 24 hours.
The deluge is expected to cause localized flooding as the powerful weather system moves across the country.
Alan O’Reilly of Carlow Weather warned: "High resolution charts starting to get #StormAusten into view, and over 40mm in 24 hours up to 1am Friday could bring a risk of some local flooding."
While Met Éireann warned of thundery rain overnight on Wednesday, it said the full impact of the storm would be felt on Thursday afternoon.
High resolution charts starting to get #StormAusten into view and over 40mm in 24 hours up to 1am Friday could bring a risk of some local flooding. The next model update will cover more of the storm and I’d expect some weather warning updates. pic.twitter.com/fJj0dqyZJp
— Carlow Weather (@CarlowWeather) October 20, 2026
The national forecaster warned: ‘Very heavy rain will develop in the southwest during the afternoon, extending northeastwards during the evening hours.
"Localized flooding is possible, especially in Munster and Leinster. Light to moderate east to northeast winds will strengthen later too. Very wet and windy across southern counties during the evening."
It continued: "Thursday night will be extremely wet and windy; possibly even stormy in places. Widespread heavy and persistent rain will affect much of the country, with some flooding expected. Cyclonic variable winds will veer northwest and strengthen overnight, reaching gale force in places. Lowest temperatures of 5 to 8 degrees.
"On Friday, lingering wet and windy weather will clear eastern counties by around mid-morning. Sunshine and well scattered blustery showers elsewhere will follow for the rest of the day, mainly affecting western counties."
And there will be yet more rain on Saturday before the weather clears.
"Saturday will be rather wet and windy early on with spells of heavy rain, turning more showery through the day. Fresh to strong and gusty south to southwest winds will reach gale force in some Atlantic areas. Humid with highest temperatures of 12 to 16 degrees, mildest across Munster and Leinster.
"During Saturday night, some thundery showers will affect the north and west, with the odd heavy shower arriving further east".
While Sunday will be dry, Bank Holiday Monday "is expected to be wet and windy. Mild and humid too."
* This article was originally published on Extra.ie.