Twelve fire engines and around 80 firefighters tackled a grass fire near Ockendon Road in Upminster.
Around four hectares of grassland was alight. Firefighters are expected to remain on scene throughout the night.
The Brigade's 999 Control Officers took more than 10 calls to the blaze.
A London Fire Brigade spokesperson said: “The warmer weather we have been having makes the ground extremely dry, which unfortunately means grassland, parks, undergrowth and woodlands will burn quickly when exposed to even the smallest of sparks.
“We don’t want people to be complacent and that means not barbecuing in parks and open spaces, ensuring cigarettes are properly disposed of and clearing away rubbish and glass as they can magnify the sun and cause a fire.”
The Brigade was called at 1938 and the fire was under control by 2250. Fire crews from Plumstead, Dagenham, Ilford, Wennington and surrounding fire stations attended the scene.
The cause of the fire is under investigation.