"While thousands of children prepare for the start of the school year, drivers should also get ready for the changed road conditions around schools," Mr Mulder said.

"Speed limits will be reduced to either 40km/h or 60km/h outside schools in the morning from 8am to 9.30am and in the afternoon from 2.30pm to 4pm."

The school speed zone limits are clearly signposted.

Police are also warning speeding drivers to slow down and obey the reduced speed limits or face hefty penalties.

State Highway Patrol Inspector Simon Humphrey said lower speed limits were in place in school zones to protect children and drivers should be extra cautious when travelling through these areas.

"Children can be unpredictable and drivers need to be aware of this," he said.

"They're excited about seeing their friends again and sharing stories about what they did on the school holidays.

"Unfortunately this excitement can lead to distraction when crossing the road or walking near parked cars.

"It's important for drivers to avoid distraction and drive safely in school zones."

Insp Humphrey said police were running a number of operations in school zones across the state and would be cracking down on those caught doing the wrong thing.

"The 40km/h speed signs are not advisory, they are mandatory," Insp Humphrey said.

"If you speed, receiving a fine is the least of your worries. Far worse is the possibility of killing or seriously injuring a young child.

"So please slow down and do the right thing - running late is nothing compared to the heartache of hitting a person.

"Consider this as a warning, because if we pull you over, we won't be accepting any excuses."