Danger changes within the day
A peer-reviewed study of three fire periods in Portugal and Spain calculated the Fire Weather Index from hourly conditions instead of daily weather inputs. Cátia Campos and colleagues used nested Meso-NH simulations at 1.5 km and 0.5 km resolution. This exposed changes through the day and the influence of coasts and terrain on the same map.[1]
Daily weather products smooth out local gradients formed by sea breezes and terrain-driven flow. In the hourly calculation, the component describing fine-fuel moisture changed with near-surface conditions. A single daily danger value can hide conditions that response teams encounter locally. The study makes that resolution gap visible.[1]
From map to practice
The result comes from model comparisons for three past periods. It does not locate future ignitions or establish that an hourly map improves decisions in the field. A proposed path into operational weather modeling can be assessed against real-use outcomes.[1]
A useful next measure goes beyond drawing smaller grid cells: how well hourly warnings align with observed weather and fire behavior. Capturing differences among coasts, slopes and times of day would show whether this approach helps response planning.[1]