SA dodged a bullet: CFS

A cool change has hit South Australia after four days of temperatures above 40C and rain is falling across the state.

After a week of extreme conditions, a cool change has finally arrived in South Australia. (AAP)

After a week of extreme conditions, a cool change has finally arrived in South Australia.

Fire crews were on high alert on Saturday after four days of temperatures above 40C, but people across the state woke up to much cooler conditions on Sunday.

CFS spokesman Mark Wheeler said a cool change arrived in the early hours of Sunday, with temperatures dropping significantly and rain falling across the state.

"There are no fire events to speak of at the moment," Mr Wheeler told AAP on Sunday.

"We effectively dodged a bullet yesterday."

Some crops were destroyed as 15 fires burnt on Saturday, started by lightning strikes, as the mercury reached 42C.