Western Sydney sweltered through its hottest ever December day on Tuesday,with a peak of 46.3 in Penrith recorded at 3.21pm. Towns along the South Coast,where the worst of the fires raged,hit the high 30s.
"What we’ve seen is some really hot temperatures develop and some really gusty north-westerly winds over southern and parts of western NSW,"NSW Bureau of Meteorology acting manager Jane Golding said.
Ms Golding said the southerly change that swept up the coast on Tuesday afternoon was bringing cooler conditions,even as it forced firefighters to contend with blazes changing direction and dry thunderstorms.
"Over the course of the rest of the day we are expecting general thunderstorms to develop,and they will cause a few problems around the fire grounds and generally,"she said.
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"For much of the state,we’re expecting markedly cooler conditions tomorrow and an easing in the wind strength as well,"Ms Golding said.
In contrast to Tuesday's weather,the central ranges region is the only area in NSW forecast to endure severe fire danger on Wednesday while the Southern Slopes and Southern Ranges will experience very high danger. All of those areas will be under a total fire ban.
Sydney and most of the south coast should have temperatures in the 20s.