A line of dangerous showers and thunderstorms is moving over NSW, with a severe storm warning issued for some central and western parts of the state, including Sydney.

A low pressure trough passing over NSW from south to north has produced a line of intense showers and storms called a 'squall line'.

Earlier in the day, the squall line moved over southern NSW and the ACT, causing areas of blustery winds and heavy rain. Wind gusts reached 95km/h at Cabramurra just before midday, around half an hour before a gust of 93km/h was clocked at Mount Ginini.

Just after 1pm, Canberra copped 12mm of rain and cooled by 7ºC in half an hour as the squall line moved through, along with a 72km/h wind gust.

Image: Composite radar/satellite/lightning strikes showing the squall line over southern NSW and the ACT at 1:20pm AEDT on Monday.

Now, the focus has shifted north.

At 3:30pm AEDT, the squall line was extending from the Illawarra Coast near Wollongong out to about West Wyalong in the state's central west, moving towards the north.

At that time, a severe thunderstorm warning was in place for parts of the Sydney Metropolitan and Illawarra Districts and parts of Central Tablelands, Southern Tablelands, Central West Slopes and Plains, South West Slopes, Riverina, Lower Western and Upper Western Forecast Districts.

The squall line will continue to move north in the coming hours, likely causing dangerous wind gusts over parts of central NSW.

Following this squall line, another area of thunderstorms is likely to develop over southeastern NSW in the early evening. This second batch of storms is likely to gain strength over the Illawarra around dinner time before moving up towards Sydney later in the evening.

Check the latest warning this afternoon and tonight for the most accurate information on this developing situation.