Fires that broke out during last year's historic wildfire season could still be smouldering underground, waiting to re-emerge as the weather gets warmer. 

That's according to a warning from the B.C. Wildfire Service, which cautioned the public to watch for so-called "overwintering" fires this spring.

Overwintering fires that are buried beneath the surface can lurk undetected for months before flaring up when conditions outside get hot and dry again, which is a particular concern after last year saw a record-breaking fire season.

"Given the extent and intensity of many wildfires in the summer of 2018, some of these residual hot spots could flare up with the arrival of warmer and drier weather this spring," the province said in a news release.

Overwintering fires usually occur within the original fire's perimeter, and the Wildfire Service said communities in those areas are being scanned using "thermal imaging technology."

Firefighters are also patrolling the areas for fire activity.

Roughly 13,000 square kilometres had burned by the end of August 2018, which made it the worst wildfire season for area scorched in B.C. history.

The previous year's season saw 12,160 square kilometres burned, but more evacuations. More than 65,000 people were forced to flee home in 2017.

Anyone who spots a wildfire or smoke, including in the area of last year's fires, is asked to report it to authorities at 1-800-663-5555 or by dialing *5555 on a cellphone.