Travel search engine KAYAK found that average prices to increasingly popular Zanzibar go from £355 in the second week of June to £803 in the first week of August.

Flights to Orlando in early June are as low as £396 but jump to £664 in the second week of August.

Malaga flights go from a reasonable £81 in the second week of July (before schools break up) to £144 in August – a 78% increase.

But there are some popular destinations where prices don’t rise or at least not as much.

Flights to Split in Croatia jump from £160 in early July to £189 during the holidays, a moderate increase of £29.

Prices to Toronto, which is now in the top 10 summer holiday destinations for British families, go from £486 in July before the school holidays to £532 later in the summer. Average flights for the fourth week of August, when the kids are still off, are £450.

Flights to Egyptian beach resort Hurghada only jump from £187 in early July to £224 in the first week of the school holidays. Even in the third week of August – the most expensive week at many destinations – flight prices remain at a reasonable £241.

KAYAK has launched an Airfare Calculator, which allows you to enter your chosen summer holiday destination and find the cheapest months to travel.