A gorse fire at Bolberry Down, South Devon, quickly spreads to the edge of a cliff.
People are urged to keep their windows and doors closed as smoke from the ongoing bushfire is blown towards homes.
Firefighters have warned residents of Bolberry and Hope Cove.
The Devon and Somerset Fire and Rescue Service said it was working to contain the “difficult” fire.
The agency said: “We are advising people in the Bolberry and Hope Cove areas to keep their windows and doors closed while the smoke from the Bolberry Down fire is blown in that direction.
“We are working hard to prevent the difficult cliffside broomfire from spreading along the coastal path.”
The fire on inaccessible cliffs at Bolberry Down rekindled last week and continues to burn.
Firefighters have even started dumping seawater onto the fire from a helicopter.
Landowners, the National Trust, said dry soil and recent warm weather likely caused the fire.
The trust, which is paying for the helicopter, said the fire service had asked people not to report “smoke or flames in the existing burned area or low under the cliff.”
It added: “If there are flames near the coastal path, call 999”.
Several fires were reported in the same area last summer.
Fire breaks are also cut into the vegetation to try and keep the fire under the coastal path.
The trust said: “Due to the inaccessible nature of the rock face and the sheer amount of heat built up in the ground, the fire service advised us to pay for a helicopter to help fight the fire.”
Gorse fires are said to be particularly dangerous during hot and sunny spells that leave the grass dry and vulnerable to flames.
A fire service statement said: “Last night’s fire is a continuation of the blaze that has flared up sporadically since May 28.
“We have three fire brigades and three water arches on site today to prevent the fire from spreading to the coastal path.
“Due to its location on the side of a steep cliff, we are unable to extinguish the fire using our usual methods.
“We recently advised the National Trust to deploy a commercial helicopter to extinguish the flames that helped the situation.
“However, we cannot send firefighters to completely extinguish the hot spots, especially as there is no risk to life or property from the fire.”