Complex sentence: Sand storms are common before summer time (from March to June), they last from 6 hours to 4 days, these storms vary in their intensity but in general they prevent any external activity and driving becomes very hazardous.
Split into simpler sentences: Sand storms are common before summer time (from March to June), lasting from 6 hours to 4 days. These storms vary in their intensity but in general they prevent any external activity and driving becomes very hazardous.