Laois Fire Service has responded to 16 incidents of flooding so far today.
There have been dramatic flooding scenes across the county, including in Clonaslee where the River Clodiagh over-flowed, threatening to flood nearby houses.
The N80 main Stradbally to Portlaoise road is now impassable, due to flooding.
AA Roadwatch has recently alerted motorists to the road closure.
The Mountmellick road in Clonaslee is also impassable.
According to AA Roadwatch, Wolfe Tone Street and Davitt Road in Mountmellick are also affected.
Assistant Chief Fire Officer Anthony Tynan has urged motorists to exercise “extreme caution” on roads, due to flooding.
He has also reminded people to look in on their elderly and vulnerable neighbours.
Earlier today, Barnashrone National School closed its doors after flood waters rose to dangerous levels.
Houses have been flooded in a number of areas including Portlaoise, Mountmellick, Clonaslee and Rosenallis.
A public premises in Portarlington on Main Street also had to be pumped out by fire crews this morning.
The north of the county was particularly badly affected by heavy overnight rainfall and flooding today.