One of the jewels of the Formula One World Championship calendar, the Singapore Grand Prix, is on this weekend.

As the only night race of the year, it provides a fantastic show under the lights held around an impressive 3.15-mile circuit, making it a favorite with fans, teams and drivers—even though it’s one of the slowest races of the year. (The average speed hovers just above 100 mph.)

Despite the low speeds, the Singapore Grand Prix is quite the challenge, mainly because of the stifling heat and humidity throughout the night. The circuit features nine low-speed corners and 15 different braking events, which is more than Monaco. This means drivers have to work much harder than usual with all the gear changes.

The Marina Bay Circuit is unusually wide for a street circuit, which makes overtaking possible, but it’s surface is slippery and littered with “street furniture” such as manhole covers. Then there’s also the tropical weather to deal with.

Ferrari at the 2016 Formula One Singapore Grand Prix

Ferrari at the 2016 Formula One Singapore Grand Prix

The peak temperature for Sunday’s race will be around 90 degrees F (32 degrees C) and storms are predicted for the entire weekend. The good news is that they tend to be brief in Singapore.

Pirelli has nominated its soft, supersport and ultrasoft compounds for the race.

The high heat and humidity is expected to hamper the performance of Mercedes AMG. Following an initial practice session on Friday, the German team’s drivers Lewis Hamilton and Nico Rosberg were only fourth and fifth fastest, respectively. Ahead of them were Red Bull Racing’s Max Verstappen and Daniel Ricciardo as well as Ferrari’s [NYSE:RACE] Sebastian Vettel.

Going into Saturday’s qualifying session, Hamilton leads the 2016 Drivers’ Championship with 250 points while Rosberg is second with 248 points and Ricciardo third with 161 points. In the Constructors’ Championship, Mercedes has 498 points versus the 290 of Red Bull and 279 of Ferrari. Last year’s winner in Singapore was Vettel.