Two north coast police commands have the highest drink driving rates in NSW.

The Tweed-Byron Local Area Command (LAC) currently has the highest rate of people caught driving while intoxicated.

Coffs-Clarence Traffic Patrol spokesman Acting Senior Sergeant Brett Jackson said the region from Yamba to Urunga has the state's second highest drink-driving rate.

"We've detected 651 drink drivers, just in the Coffs-Clarence area up to the end of last month," he said.

"So that was from the 1st of July last year to the end of April.

"Comparisons with Sydney City LAC for the same time, that's The Rocks and the city there in George Street in the middle of Sydney, is 191 Kings Cross is 184.

"So 651 is quite a significant number."

The high rate of drink driving in the Coffs-Clarence area has prompted local police to step-up random breath testing.

For the past couple of weeks police have been doing regular morning checks, on top of those typically done later in the day.

Acting Senior Sergeant Brett Jackson said many people do nt realise they can still be over the limit from drinking the night before.

"It's quite common that we do detect at least one drink driver every couple of mornings and it usually is the case where they had the big night the night before and they believed they were right to drive to work," he said.

"That's the scary part also, that they were actually going to go to work while still intoxicated.

"Coffs Clarence has traditionally had a high PCA detection rate at the moment we're the second highest in the state."