The Hot-Dry-Windy
( HDW )
(1)
surface wind speed times,
and
(2)
the water vapor pressure deficit.
which is related to relative humidity,
( temperature and dew point temperature ),
but is a difference,
rather than a ratio,
HDW measures
the potential of air
to remove moisture
from dead vegetation.
A low relative humidity,
and a high temperature,
would dry dead vegetation
the fastest.
The HDW index shows
if the current weather
would promote the
rapid spread of a fire
... if a fire had started.
Actual fire danger
depends on the
amount of fuel
in the forest,
and how dry it is.
30 years of
weather forecast
model (GFS) data
were used to build
a website that gives
daily forecasts of the
HDW index,
