According to calculations from Peggy LeMone, senior scientist at the National Center for Atmospheric Research, an average thunderstorm cloud contains approximately 275 million gallons of water. To help put this in perspective, with 750,000 gallons of water going over Niagara Falls each second, it would take six minutes for that amount of water to go over the Falls.
Since one gallon of water weighs 8.33 pounds, the weight of the cloud would be 2.3 billion pounds (about 1.1 million tons).
NOAA's National Weather Service calculates that one inch of rain over one square mile equals 17.4 million gallons of water which would weigh 143 million pounds (about 72,000 tons). This is the approximate weight of a train with 40 boxcars. By these calculations a typical cloud would weigh the equivalent of more than 17 of these trains!
God truly is amazing!!