Complex sentence: No tropical storms developed in June in the basin, although typically two form in the basin during the month; since 1966, there were only four seasons in which a tropical storm did not form in June, the others being 1969,2004, and 2007.
Split into simpler sentences: No tropical storms developed in June in the basin, which was unusual compared to the average of two storms forming during the month. Since 1966, there have been only three other seasons in which a tropical storm did not form in June, the others being 1969,2004, and 2007.