NLDN flash density (# of flashes per km2 per year)
June 1995-2008
NLDN flash density (# of flashes per km2 per year)
July 1995-2008
NLDN flash density (# of flashes per km2 per year)
August 1995-2008
NLDN flash density (# of flashes per km2 per year)
June, July, August 1995-2008