New research suggest that weekdays bring heavier downpours than
weekends. The cause could be the air pollution created by the greater
amount of traffic and business operations on weekdays.
The study looked at data collected by NASA's Tropical Rainfall
Measuring Mission satellite from 1998 to 2005. They found it rains, on
average, more between Tuesday and Thursday than between Saturday and
Monday. The clearest day of the week was Saturday, with about half the
rainfall of the wettest day.
The airborne particles associated with pollution, also tended to peak midweek as well.