The Nesterov Index is a simple fire danger rating created in Russia in 1949.
It can be calculated once daily from:

N = Y +  (T-D) x T

where
N is today's new Nesterov index
Y = Yesterday's Nesterov index value
T = Today's high air temperature in ° C.
D = Today's low dew point in ° C.

and N is reset to 0 after a rainfall of  3mm (0.12') occurs.
 

For "N"	Nesterov Fire Danger
N < 300	None
301 < N < 1,000	Moderate
1,001 < N ≤  4,000	High
N > 4,001	Extreme