Spring will be in the air across Sydney during the next week, with temperatures forecast to reach a five-month high in some parts of the city.

Warm inland air will be carried over the Sydney Basin this weekend and in the middle of next week as westerly winds develop ahead of approaching cold fronts.

This weekend, daytime maximum temperatures are forecast to reach the low-to-mid twenties on Saturday and 25-26 degrees on Sunday across Sydney.

While cooler weather will briefly return for a couple of days early next week, the next round of warm westerlies sweep over Sydney from Wednesday.

Temperatures should reach the mid-to-high twenties across the Sydney Basin next Wednesday and Thursday, possibly nudging 30 degrees in some western suburbs on Thursday afternoon.

For most suburbs, next week's warmth should bring the highest temperatures since April or May.

This type of warmth isn't unusual in Sydney at this time of year. Days typically start to get warmer as winter transitions into spring and warm inland air pushes towards the NSW coast. Spring in Australia officially starts next Tuesday on the first day of September.