Table 1.

Inputs to wet-bulb globe temperature (WBGT) algorithm.

Variable	Calculation	Units/Notes
Year	Provided by ERA5-Land	Numeric (YYYY)
Month	Provided by ERA5-Land	Numeric (MM), 1–12
Day	Provided by ERA5-Land	Numeric (DD), 1–31
Hour	Provided by ERA5-Land	Numeric (HH), 0–23 in local time
Minute	Set to 0 for all observations	Top-of-hour observations
UTC Offset	Set to 0 for all observations because we calculated on the original UTC data	Number of hours difference from UTC, if applicable
Averaging Time	Set to 0 for all observations	Observations are provided as either instantaneous or already averaged over the hour
Latitude	ERA5-Land grid centroids	Decimal-degrees North (°N)
Longitude	ERA5-Land grid centroids	Decimal-degrees East (°E)
Ambient Temperature	Provided by ERA5-Land	Degrees Celsius (°C)
Relative Humidity	$e=610.94\cdot exp\left(\frac{17.625\cdot T_D}{243.04+T_D}\right)$	TD = dew point temperature (°C); see Lawrence (2005)49
	$e_s=610.94\cdot exp\left(\frac{17.625\cdot T_A}{243.04+T_A}\right)$	TA = ambient air temperature (°C); see Lawrence (2005)49
	$RH=100\cdot \left[\frac{e}{e_s}\right]$	e = vapor pressure (Pascals [Pa]) and es = saturation vapor pressure (Pascals [Pa])
Surface Solar Radiation Downward	Provided by ERA5-Land	Watts per square-meter (W/m2)
Wind Speed	$ws=\sqrt{u^2+v^2}$	u = zonal wind velocity (m/s) and v = meridional wind velocity (m/s)
Surface Pressure	Provided by ERA5-Land	Pascals (Pa)
Wind-Speed Height	Set to 10 meters for all observations	N/A
Temperature Lapse	Set to −0.052 °C for all observations	Assumes vertical lapse rate of −6.5 °C / km
Urban	Assigned 1 (urban) to pixels classified as urban or built up in the National Land Cover Database 2011 dataset and 0 (rural) otherwise	N/A