"Yay, it rained!" Parks Canada spokeswoman Kim Weir said Saturday during an update on the 50-square-kilometre blaze.
Weir said four to six millimetres of rain had fallen overnight and more was expected, giving firefighters a chance to get on the ground and attack the flames directly.
"This rain and the forecasted weather over the next few days will reduce fire behaviour potential and allow fire crews to safely work on priority areas of the fire," she said.
"This is a huge shift."
The fire was not yet contained, but did not get any bigger, Weir said.
"Under current conditions, we do not expect it to grow."
No facilities were threatened and the Jasper townsite was safe, Weir added. However, the Maligne Valley and the scenic Skyline Trail remained closed to campers and hikers.
A fire ban was extended to all the mountain parks, including Banff, Yoho, Revelstoke, Glacier and Kootenay.
All other campgrounds and day-use areas were open.
Weir couldn't say when the Maligne Valley may be reopened.
"It's a ways down the road for sure. We would only open it if — and only if — we determine it's 100 per cent safe for people to be in that area ... as well as drive the road down to the Maligne Valley.
"It's impossible to tell right now. That depends largely on Mother Nature."
Maligne Lake itself is a popular destination for tourists, canoeists and back-country campers because of its stunning scenery. The water shimmers in hues of turquoise, blue and green and the lake is surrounded by a ring of majestic mountains capped by glaciers.
Weir said there is no reason people shouldn't visit the Jasper park, but she did warn that some areas could be smoky.
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