Spring's first burst of heat for Sydney could produce the first 30-degree readings of the city, as warm, dry winds nudge fire danger levels into the "very high" ratings for parts of NSW.

On current forecasts, Sydney can expect 28 degrees at Observatory Hill and 30 degrees in Richmond and Penrith on Wednesday, the Bureau of Meteorology said.

Temperatures are likely to back off along the coast on Thursday and Friday before climbing back to the high 20s on Saturday. Western suburbs, though, will again nudge 30 degrees on Saturday.

Sydney can expect the temperature to reach the high 20s on Wednesday. Credit:Dallas Kilponen

"It could be touch and go" whether 30 degree totals are reached in coming days, Tom Hough, a meteorologist with Weatherzone, said. "Certainly, we'll get the high 20s."