Tasmania has experienced its hottest recorded March, breaking the record set nearly 30 years ago.

Across the state, the average March temperature was 15.7, breaking the record set in 1974 by 0.3 degrees.

The average high temperature was 21 degrees, with Bushy Park recording the state's hottest day of 37 degrees.

Ian Barnes-Keoghan from the Bureau of Meteorology says it was an exceptionally hot start to the month.

"From about the 2nd to the 13th, there was a high pressure system sitting over the Tasman Sea that persistently brought warm air down over south-east Australia, and on to Tasmania," he said.

"What we saw across that south-east was a persistent heatwave, temperatures just didn't cool down."