Firefighters on Vancouver Island say a "significant" amount of rainfall has helped crews to make progress in battling an out-of-control wildfire, which is burning south of Port Alberni, B.C.

Officials on Vancouver Island say 33 millimetres of rain on Friday helped to curb the flames of the Mount Underwood wildfire, which is burning about 8 kilometres south of Port Alberni, B.C.

Visibility for BC Wildfire Crews is an issue on Friday due to the fog and the weather, which will limit the ability to fight the fire from the air.

Firefighters on Vancouver Island say overnight rain has helped calm an out-of-control wildfire near Port Alberni, B.C.

Environment Canada is forecasting rain all day Friday and into the weekend in the area, which could aid firefighters battling the blaze. The area around Port Alberni could get up to 20 millimetres on Friday,

The wildfire set off the evacuation of the China Creek Campground and Marina, which has 250 tent and RV campsites and is about 15 kilometres southwest of Port Alberni. The service says the highway between Port Alberni and Bamfield has been closed due to the fire.

The wildfire that has triggered evacuation orders and alerts on south-central Vancouver Island is billowing smoke that has prompted Environment Canada to expand an air quality advisory to the northern Gulf Islands and Sunshine Coast.