Sydney's near-perfect beach conditions on Wednesday, with parts of the state reaching a high of 37 degrees, were shattered by thunderstorms and gale-force winds in the late afternoon and evening.

Lightning and heavy rain struck the state at about 5pm causing Fire & Rescue NSW to respond to 70 storm related incidents.

The NSW State Emergency Service (SES) took about 145 calls since the storm started.

Most of the calls were in Sydney's west including Blacktown, Campbelltown, Liverpool and Penrith.

"The calls were mainly about fallen trees and branches, roof damage and localised flooding. There have been no known injuries," a NSW SES spokesperson said.

"There has been quite heavy rainfall and power outages. The southern and western Sydney areas were high in activity."

The view of hail on the #M4 in Sydney #storm a short time ago. @MoneyNewsShow Tks to Vito Transport @2GB873 pic.twitter.com/hQB4yhiC1l — Ross Greenwood (@Ross_Greenwood) March 11, 2015

Freaky sky just before armagedon hit #storm pic.twitter.com/R8w6fwJu59 — Lanni P (@Leanpo) March 11, 2015

Earlier on Wednesday evening, the roof of a house fell on train tracks near Mount Druitt station causing the partial closure of the T1 Western Line and Blue Mountains Line between Penrith and Blacktown.

The Bureau of Meteorology reported at 8.30pm that the threat of severe thunderstorms has passed for Sydney, Newcastle, Wollongong and their surrounding areas as well as the Illawarra and Lower Western districts.

The NSW SES said there has been a steep decline in calls since the storm waned.

The bureau however warned however severe thunderstorms which are likely to produce large hailstones, heavy rainfall leading to flash flooding and damaging winds could affect Cessnock, Mudgee, Dubbo, Wellington, Nyngan and Bourke late Wednesday night.

Central Sydney reached a high temperature of 31 degrees on Wednesday.