Relationships between synoptic weather patterns, surface fire weather and vegetation fire in a temperate region

Background: Vegetation fire risk is increasing in temperate regions like the UK, yet understanding of surface and synoptic weather controls on fire is limited. 

Aims: We examined seasonal relationships between (i) synoptic weather patterns and surface fire weather, (ii) surface weather and vegetation fire, and (iii) synoptic weather patterns and vegetation fire in England using a comprehensive fire database. 

Methods: We used ranked percentile curves and relative difference metrics to address our three objectives. 

Key results: Extreme surface fire weather is predominantly associated with high-pressure systems. The best surface weather predictors of fire are relative humidity (RH), fire weather index (FWI), fine fuel moisture code (FFMC) and initial spread index (ISI). Vegetation fires are strongly associated with high-pressure synoptic weather on the day of, and the week before fires in spring, but much less so in summer. 

Conclusions: Persistent high-pressure synoptic weather is required to sufficiently elevate surface fire weather for vegetation fires in spring. Summer fires are less dependent on the specific synoptic weather pattern and extreme summer surface fire weather. 

Implications: Incorporating both synoptic and surface fire weather may help to capture seasonal differences in the drivers of vegetation fire and provide opportunities for longer-term forecasting of elevated fire weather.