A school bus of Iowa children stopped outside the house of an elderly woman to wish her a happy birthday and wave through windows across the street.

Bonnie Linder was due to celebrate her 93rd birthday, according to reports.

She waves to the children on the bus every weekday from her home in the small town of Hartley, CBS News reported.

But to mark her birthday, the children and their driver stopped to wish her happy birthday from their bus,

A video filmed by Judy Zimmerman, Ms Linder’s daughter, caught the heartwarming moment as cheers spilled from the bus.

CBS News reported that Ms Linder's other daughter gave the driver the tip-off that her mother’s birthday was coming up and that Ms Linder had no idea she would be expecting such a heartfelt greeting.

“Mom had NO idea...and the morning sun could NOT have been more perfect!” Ms Zimmerman told CBS News.

She continued: “Although you cannot see her face, she was SOOOO HAPPY!!! The kids all were in on it with the bus driver and were excited to be able to stop!”

Ms Linder first started waving to the school bus at the beginning of this school year, CBS News said.

“She sits in her rocking chair at her picture window and looks down the gravel road to watch for it,” said Ms Zimmerman.