People living in eastern NSW should brace themselves for a spate of severe thunderstorms, bringing with them the risk of costly damage, the Bureau of Meteorology and the State Emergency Service warn.

The end of the La Nina weather pattern that dominated eastern Australia over the past two years means a reversion to a more normal hot and humid summer, said Michael Logan, Sydney-based manager of the bureau's severe weather section.

More of these to come. Credit:Viki Lascaris

"On average season, we see over 50 severe thunderstorm days," Mr Logan said, adding that many of those days will see multiple storms. North-eastern regions are likely to see the most.

While there was no indication that this storm season will be any worse than the long-term average, Mr Logan said it was important for people to be alert.