Dean Field Community Primary School is closed today after heavy downpours last night.
Dawn Edwards, business manager at the school, said the fire alarm system had been left water damaged after the heavy rain, so the school could not open for health and safety reasons.
She said an engineer was on site this morning to resolve the issue.
Water also damaged some of the classrooms and resources, but staff have been at the school all day to ensure it can reopen tomorrow.
For much of yesterday, Calderdale was bathed in sunshine with temperatures said to have been as hot as they have been in September since 1911.
But by early evening, the heavens opened and the region was blighted by torrential downpours as storms hit.
The Met Office issued a yellow warning for rain for the North West, North East, Yorkshire and into parts of Scotland saying the deluge could cause flash flooding and travel disruption.