The Belgian Grand Prix rarely takes place without a passing rain shower at some point over the weekend. That’s because the Spa-Francorchamps circuit is located in Belgium’s High Fens region, which is notorious for having its own microclimate.

This fickle Ardennes weather can result in bright sunshine one moment, followed by a deluge of epic proportions the next - or just a steady stream of grey drizzle. It’s the one race of the year where the forecast is difficult to predict and drivers must be prepared for wet-weather driving at some stage.

Pirelli brings to every Grand Prix a number of intermediate and full wet tyres. On a typical weekend, each driver has access to four sets of Cinturato intermediates (identifiable by a green sidewall) and three sets of full wets (with a blue sidewall). However, during a Sprint weekend - as the Belgian Grand Prix will be this week - the allocation changes to five sets of intermediates and two sets of wets.

According to Pirelli, the intermediates are the most versatile of the rain tyres. They can be used on a wet track with no standing water, as well as on a drying surface. The compound has been designed to have a wide working range, providing a broad crossover window with both the slicks and the full wets.

At 185mph, a single intermediate tyre can disperse around 35 to 40 litres of water per second. That means a Formula One car at full speed on the Kemmel Straight can shift around 150 litres of water per second when running on intermediates. The full wet tyres are more effective in heavy rain, capable of dispersing double that of the intermediates.

But if it rains heavily, visibility rather than grip becomes the main issue, and that problem is exacerbated at Spa because the mist hangs in the trees lining the circuit. It’s also important that drivers exit the garage wearing a helmet fitted with a clear visor, rather than a tinted one, to help with visibility.

The biggest issue with heavy rain on a track as undulating as Spa is that rivers can form across the circuit, causing aquaplaning. This is when the cars literally skate on the water, making it impossible to brake or steer. The Belgian circuit has grooves cut into certain parts of the track to reduce the likelihood of skidding, but when it does happen, the Race Director will stop the session or race.

The weather at Spa can lead to some bizarre occurrences. Back in 2021, the Belgian Grand Prix was delayed for three hours as organisers waited for the track to dry. Ultimately, the race was suspended after just three laps - two of which were behind the Safety Car. In terms of race distance, it is the shortest in the 75-year history of the World Championship, at just 4.285 miles - or one classified lap. With rain forecast across all three days, let’s hope the rain isn’t as intense this year!