Roberts was seen carrying the children's jackets as the family enjoyed a visit to the Westport House Pirate Adventure Park in Co Mayo.
The Oscar winner was spotted enjoying the sun with four young children at the adventure park.
The mother-of-three is holidaying in the Louisburgh area, about 22km west of Westport.
She has been seen at a number of local beaches in recent days including Silver Strand and Old Head.
Managing director of Westport House, Karen Browne, said Roberts made no advance special arrangement to visit the park. Ms Browne, whose family have had a connection with the house for 300 years, said she spoke briefly with the star.
"She just said she was having a lovely day and she was really enjoying the place. "That was it. I got the feeling she just wanted a quiet time."
And while the ' Erin Brockovich' star has been relatively lucky with the Irish weather so far, heavy and persistent rain is expected later today.
The 'Michael Collins' actress has strong links with Ireland, thanks to her close relationship with driver Mick Devine.
The pair became firm friends more than a decade ago when Roberts broke up with her then fiance, Kiefer Sutherland, just days before the ceremony.
She reportedly called for a taxi at 2am and asked him to pick her up from the Shelbourne Hotel -- and he brought her to stay in his three-bed semi in Palmerstown to avoid the media attention. Since then, Roberts has made regular trips here.