Perth is forecast to get within a degree of its April maximum temperature record on Saturday.

After reaching 32 to 34 degrees between Monday and Thursday, Perth is forecast to hit 36 degrees on Friday and 37 degrees on Saturday. This lengthy spell of hot weather is being caused by a slow-moving high pressure system to the south of the state, which is directing warm inland air towards the west coast. 

Image: Forecast surface air temperature on Saturday afternoon, according to the ECMWF-HRES model.

Perth's forecast maximums on Friday (36C) and Saturday (37C) put the city on track to register six days at or above 31.8 degrees, which will be a new record for April.

Saturday's forecast of 37 degrees will also challenge the city's April maximum temperature record of 37.6 degrees from 1910.

Temperatures will drop from Sunday as cooler westerly winds develop over Perth, with the mercury forecast to reach highs of 27 degree on Sunday and Monday.