Formula 1 has this weekend returned from its summer break at a slightly modified Spa-Francorchamps circuit for the Belgian Grand Prix.

Broader changes are planned for the venue next year as it targets a return of motorcycle racing, though more subtle changes have been made since F1 last visited.

Notably, that includes tweaks to the barrier in the endurance pit lane, which has seen that entry extended back towards La Source.

At Eau Rouge, the apex kerb has been replaced with a ‘double negative kerb’.

Further around the lap, at Les Combes and Campus, the width of the kerbing on exit has been reduced in width to a maximum of two metres from the edge of the racing surface.

Officials will again be monitoring track limits, with three locations of key interest.

Specifically, these include the exit of Turns 4, 9, and 19 – namely Raidillon, the unnamed right-hander following Bruxelles (sometimes referred to as Speakers Corner), and the left-hander exiting the Bus Stop Chicane.

A lap time achieved during practice or the race by exceeding limits, defined by the back edge of the apex or exit kerb at those locations, will result in the lap time being deleted.

In the race, a third track limits transgression will see the driver referred to the stewards and potentially accrue a penalty.

Further to the track limits locations, drivers who go off at Les Combes have been asked to use the return road which feeds them back onto the road at Malmedy.

Weather conditions are expected to be mixed throughout the weekend, with wet weather greeting teams for the start of Free Practice 1.

Rain clouds are expected to remain all weekend, with temperatures tipped to scarcely rise above double figures.

Opening practice in Spa-Francorchamps began at 19:30 AEST.