PRINCE GEORGE, B.C. -- An unexpected spike in wind has spoiled the prospect of better firefighting conditions in British Columbia's Central Interior, where crews are struggling to make headway against the first major blaze of this year's fire season.

B.C.'s Fire Management Branch welcomed Monday's forecast of cooler temperatures and lighter winds in the fight against the Little Bobtail Lake fire, about 70 kilometres southwest of Prince George.

But favourable wind conditions had waned by the afternoon, prompting the blaze to grow to 250 square kilometres -- a jump from Sunday's estimated size of 240 square kilometres.

"It's a complex fire," said Peter Goode of the Fire Management Branch on Monday, speaking by phone from the crew's base camp about two dozen kilometres south of the flames.

"It's unpredictable because of the wind."

Goode listed several other factors that have contributed to the fire's complexity: different types of wood, a mixture of harvested and unharvested areas, swamps and the intermittent presence of snow.

Fire crews managed to contain 20 per cent of the blaze by Saturday, but that number had fallen to 15 per cent by Monday after strong winds fanned the flames, causing the fire to spread.

More than 300 personnel have been assigned to the fire, including 270 firefighters, 13 helicopters, 22 pieces of heavy equipment and eight air bombers.

The blaze was first reported on Friday, May 8 and is easily visible from nearby Highway 16.

So far, it has forced about 80 people from their homes around Norman Lake and Bobtail Lake, while dozens more around nearby Bednesti and Cluculz lakes remain on evacuation alert.

The RCMP have said they believe the Little Bobtail Lake fire was human-caused and that they have determined the origin of the blaze, though an investigation is still underway to determine its exact cause.

B.C. fire officials said this level of activity so early in the year could indicate the province is in for a busier-than-usual fire season in 2015.