West Yorkshire and Lancashire fire crews have battling a 200m wildfire on Widdup Road, in Hebden Bridge, since around 12.25pm today (April 19).
Three fire engines from Lancashire Fire and Rescue Service, and five fire engines and two specialist fire units from West Yorkshire Fire Service have attended the scene.
Smoke from the fire can be seen as far as Great Harwood, according to members of the public.
A spokesperson for West Yorkshire Fire Service said: “Moorland fire has now been increased to make pumps eight plus several specialist wildfire appliances and crews.
"Appliances from across West Yorkshire, Lancashire and GMC currently in attendance."
Beaters, water backpacks and blowers are being used to tackle the blaze, and one Argocat, an all-terrain vehicle, has been deployed.
Members of the public have been asked to avoid the area.