VANCOUVER - The BC Wildfire Service says a fire burning in British Columbia's southern Interior doubled in size over a 24-hour period to about 2.5 square kilometres.

More than 100 people, supported by aircraft and heavy equipment, are battling the blaze that broke out Aug. 4 north of Oliver.

The fire activity had calmed late Monday, but that could change as Environment Canada forecasts the heat will remain in the low- to mid-30s through the week, with no rain forecast until Saturday.

An evacuation alert prompted by the fire was issued Monday by the Regional District of Okanagan-Similkameen which covers 206 properties north of Oliver.

Steep and rocky terrain is complicating firefighting efforts and the wildfire service says a structure protection specialist and incident management team are at the scene.

Cool and damp conditions in July kept a lid on the wildfire risk across B.C.