A Example climate indices

A.1 Climate index (variable) definitions

Element	Climate Index	Definition	Units
Tmax	Hot days	No. of days with Tmax > 30 °C	days
	Summer days	No. of days with Tmax > 25 °C	days
	Ice days	No. of days with Tmax < 0 °C	days
Tmin	Frost days	No. of days with Tmin < 0 °C	days
	Tropical nights	No. of days with Tmin > 20 °C	days
	Cold alerts (Toronto)	No. of days with Tmin ≤ -15 °C	No. of alerts
	School closure	No. of days with Tmin ≤ -40 °C	school days
Tmean	Heating degree-days	No. of degrees below 18 °C for each day.	degree-days
	Cooling degree-days	No. of degrees above 18 °C for each day.	degree-days
	Freezing degree-days	No. of degrees below 0 °C for each day.	degree-days
Precipitation	Dry days	No. of days with < 1 mm precipitation	days
	Wet days	No. of days with > 1 mm precipitation	days
	Drought risk	More than 10 consecutive dry days	No. of alerts

A.2 Climate index Python expressions

Climate Index	Type	Code
Hot days	Boolean	int(x > 30)
Summer days	Boolean	int(x > 25)
Ice days	Boolean	int(x < 0)
Frost days	Boolean	int(x < 0)
Tropical nights	Boolean	int(x > 20)
Cold alerts (Toronto)	Boolean	int(x <= -15)
Heating degree-days	Lambda	lambda x: 0 if x >= 18 else 18 - x
Cooling degree-days	Lambda	lambda x: 0 if x <= 18 else x - 18
Freezing degree-days	Lambda	lambda x: 0 if x >= 0 else 0 - x
Dry days	Boolean	int(x < 1)
Wet days	Boolean	int(x > 1)