Perth is on track to register its highest number of 30 degree days in March for nine years.

Monday was Perth's 14th day at or above 30 degrees so far this month. This tally is forecast to reach 18 days by Friday, which would be the city's highest number of days this hot during March since 2011.

In records dating back to 1897, Perth has only had more than 18 days at or above 30 degrees during March on five occasions. These were:

• 22 days in 2011
• 21 days in 1998 and 1948
• 20 days in 1989 and 1983

The city's hottest day so far this month has been 35.3 degrees, which is well below the March record of 42.4 degrees from 2007.