Global 0.25° daily observed and counterfactual fire weather index (1979–2024)

This is the associated dataset and code for the paper \"Increasing Synchronicity of Global Extreme Fire Weather.\" To identify synchronous fire weather, we calculate daily Fire Weather Index (FWI) at 0.25° resolution for the period 1979–2024 using fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis (ERA5) data, based on daily maximum air temperature, daily minimum relative humidity, daily mean wind speed, and daily total precipitation. We also apply an overwintering procedure in our calculations that accounts for inter-seasonal drought in cold climates. To assess the contribution of anthropogenic climate change, we apply the same methodology to derive counterfactual FWI that removes the first-order influence of modeled climate change in the variables used to calculate FWI. The counterfactual is constructed by subtracting the low-pass filtered signal of monthly changes in temperature, humidity, wind speed, and precipitation relative to a quasi-preindustri..., , , # Global 0.25° daily observed and counterfactual fire weather index (1979–2024)

Dataset DOI: [10.5061/dryad.cfxpnvxkp](10.5061/dryad.cfxpnvxkp)

## Description of the data and file structure

We calculate daily Fire Weather Index (FWI) at 0.25° resolution for the period 1979–2024 using ERA5 reanalysis data, based on daily maximum temperature, minimum relative humidity, mean wind speed, and total precipitation. An overwintering procedure is applied to account for inter-seasonal drought in cold climates.

To derive counterfactual FWI, we apply the same methodology to input fields adjusted to remove the first-order influence of anthropogenic climate change. This adjustment is made by subtracting the low-pass filtered monthly climate change signal (relative to 1850–1900) from ERA5, using the multi-model mean of 20 CMIP6 models: ACCESS-CM2, AWI-CM-1-1-MR, CanESM5-CanOE, CMCC-ESM2, CNRM-CM6-1-HR, CNRM-CM6-1, CNRM-ESM2-1, EC-Earth3-CC, EC-Earth3-Veg-LR, FIO-ESM-2-0, GFDL-ESM4, HadGEM3-CG31-LL...