A lightning strike started the fire on Blackcomb Mountain Thursday. (Submitted by Greg Norgaard)

A spot of rain Thursday night helped dampen a quickly spreading forest fire on Blackcomb Mountain, and fire officials say the blaze at the Whistler ski resort north of Vancouver is no longer spreading as rapidly as before.

The fire's rating was downgraded from four to two — a creeping ground fire — on a six-point scale on Friday morning.

Officials also reduced their estimates for the size of the blaze to about 30 hectares in size, less than a half of original size they estimated on Thursday afternoon.

Heavy smoke made it difficult to accurately determine the fire size on Thursday, but fire officials used aerial surveys and satellite images to more accurately map the blaze overnight, officials said.

The Blackcomb fire is burning in an area known as Crystal Ridge, but is still one kilometre from any structure and five kilometres from the nearest residence, officials said Friday morning.

Blackcomb Mountain will be closed to tourists on Friday, but neighbouring Whistler Mountain, the Peak-to-Peak gondola linking the two ski areas, and businesses in the village were expected to open, staff at the mountain said.

Weather key in firefighting efforts

Whistler fire chief Rob Whitton said the weather conditions will be key factors as about 34 firefighters and a half-dozen air craft attempt to extinguish the blaze on Friday, with winds of up to 30 kilometres per hour and more lightning storms in the forecast.

Air tankers dropped water and fire retardant on the fire Thursday. (Submitted by Neil Brown)

"As the day heats up, the fuel heats up as well. If we get high winds … it's really up to Mother Nature and how fast we can get in there," said Whitton.

Much of B.C. has been experiencing a week-long heat wave with record-setting temperature and thunderstorms sparking hundreds of wildfires across the province. Twenty-six fires were started in the coastal fire region on Thursday alone, said officials.

The blaze was started by lightning on Thursday afternoon and dry conditions helped it grow from about two hectares to just under 30 hectares in a little over two hours.

At the time the fire broke out, nearly 400 hikers, sightseers and staff were already being evacuated from the mountain because of the lightning strikes, staff said, but the area was completely evacuated to allow several water tankers and helicopters to start fighting the blaze.

The sliding centre for the 2010 Winter Olympics is located near the Upper Village area on Blackcomb, but the fire is burning on the other side of the mountain away from the Olympic venue.

With files from The Canadian Press