UPDATE, 11.50am: A TIGER shark has been tagged and released from SMART drumlines at Ballina's Sharpes Beach this morning.

The DPI said the 2.26m shark was caught at 11.45am.

Meanwhile, Surf Life Saving NSW has also advised that a shark was spotted at nearby Flat Rock and lifeguards have closed the beach at 11am.

Original story: AS the temperature is set to sizzle, an increase in shark activity has closed at least two popular beaches across the region this morning.

Surf Life Saving Far North Coast duty officer Jimmy Keough said people should be aware that beaches at Ballina and Evans Head are closed after sharks were spotted earlier today.

"At Ballina, Shelly Beach has been closed since 8:48am," he said.

"We were advised a DPI (Department of Primary Industry) aerial patrol spotted a shark, the beach has been evacuated and lifeguards are surveying the area."

Mr Keough said the beach at Evans Head has also been closed until further notice.

"At 8:21am we had a code 16 report which means multiple sharks, were seen off Evans Head Beach," he said.

"We ask all beach goers to follow directions of lifeguards on duty and we recommend they stay out of the water."

Mr Keough said all Surf Life Saving drones are operational in Northern NSW Far North Coast within the Ballina, Yamba, Evans Head and Byron areas.

"If anyone spots a shark at a patrolled beach we ask them to inform lifeguards," he said.

"If they spot sharks at a non-patrolled area then the best thing to do is dial Triple 0 to contact police and then the lifeguards will be informed."