Parts of Sydney could be hit by thunderstorms on Friday as a band of rain and severe storms spreads across NSW.

Friday morning was a quintessential summer's morning in Sydney. The sun was shining and the temperature had already reached 30ºC in the city and 33ºC at the airport by 10am. It was also a calm and muggy morning, with the relative humidity close to 70 percent at 10am, making the temperature feel like 35ºC in the city.

But while Sydney was basking in warm and settled weather to start the day, it was a different story on the other side of the Great Dividing Range.

Friday's first light revealed thunderstorms sweeping across the state's Central West Slopes and Plains. These dawn storms were occurring thanks to a low pressure trough interacting with moisture-laden air flowing in from the east and a pool of cold upper-level air moving in from the west.

Image: Showers and Thunderstorms over central western NSW at 10:16am on Friday.

This trough will continue to produce intense showers and thunderstorms over NSW throughout Friday as it gradually moves from west to east.

By 10am AEDT, the area of NSW being affected by thunderstorms had grown to more than 300 km in length, stretching from about Coonamble to the Blue Mountains. At that time, a severe thunderstorm warning was in place for heavy rain and damaging winds in parts of the Central Tablelands and parts of Hunter, North West Slopes and Plains and Central West Slopes and Plains Forecast Districts.

Image: A storm near Dubbo Airport on Friday morning. Source: @dr_russell / Instagram

Showers and thunderstorms will continue to spread further east today, which will put Sydney and surrounding areas of eastern NSW at risk of severe storms.

Friday's stormy weather in Sydney will be followed by a blustery southerly change in the late afternoon or early evening. This change will replace today's warm air mass with a much cooler one and after reaching about 33ºC on Friday, Sydney is only forecast to hit 24ºC on Saturday.