Four fire engines and around 25 firefighters tackled a grass fire on Orpington Road in Chislehurst.
Around one hectare of grass in a seven hectare field was damaged by the fire. There were no reports of any injuries.
A London Fire Brigade spokesperson said: “This fire occurred after the hottest spell of weather so far this year and extended periods of hot and dry weather can increase the risk of a grass fire.
"It only takes a spark to ignite a fire and grass fires can be unpredictable and spread very quickly, causing significant amounts of damage. During this type of weather, we ask that Londoners follow crucial safety advice that will help protect themselves, others, the environment and even their property.
"If you are visiting an open park or space, please do not take a disposable barbecue with you – in fact disposable BBQs are banned in many of London’s parks and you can be fined if you are caught ignoring this ban. Discarded smoking materials and leftover rubbish also pose a huge fire risk. People are asked to ensure their rubbish is placed securely inside a bin or to take it home with them and if you have had a cigarette, please make sure that it is completely out.
“We’ve been working hard to prepare and respond to weather like this but we need everyone to play their part to reduce the risk of fires occurring.”
The Brigade was called at 1653 and the incident was over for firefighters at 1827. Crews from Orpington and Biggin Hill fire stations attended the scene alongside the Brigade's All Wheel Drive vehicle.