Summer is set to return by the end of the week, with parts of the country touching 30 degrees as the school holidays get into full swing.

Weather bureau Weeronline said the temperature would rise by a degree or two every day from Monday, when most parts were cloudy with 17 or 18 degrees.

Schools in the Midden region are the last to break up for the summer this year on Friday. The Noord region finished last week and the Zuid schools have been on holiday since July 6.

Warmer, brighter conditions will move in from the south, raising the thermometer to 20-22 degrees on Tuesday and to around 25 degrees by Thursday.

Inland regions will reach 26-28 degrees at the weekend, while the early days of next week could take some areas past the 30 degree mark. However, cloudy spells and showers are also expected and there is a chance of thunderstorms on Saturday.