A Perth woman who police say appears "normal" and just like "everyone's mother or grandmother" has been charged over a spate of alleged arson attacks in Perth's southern suburbs.

WA Police allege the 48-year-old Aubin Grove woman lit several bushfires on Saturday in South Lakes, Jandakot and Cockburn.

She is also accused of lighting a further two fires in Yangebup and Cockburn.

"Some of the instances we'll be alleging [occurred] relate to paper thrown from cars or just stopping and lighting fires," arson squad Detective Senior Sergeant Craig White said.

"She's a 48-year-old woman, appears to be normal like everybody else's mother or grandmother ... nothing unusual about this particular person."

Detective White said she had been charged with seven counts of wilfully lighting a fire which is likely to injure, which under the WA Bushfires Act can carry up to 20 years in prison.

The woman is expected to appear in court later.