Weather in Great Falls Park is typical for the mid-Atlantic.  There are four seasons, with no extremes in temperature.  Summers can be hot and humid, so be sure to bring water with you.  The average temperature in summer is approximately 75 degrees F.  Summer days in the mid-90's with high humidity are not uncommon.  Winters can vary in temperature, with the average temperature for Virginia at approximately 36 degrees F.  Snow is fairly rare.  When it does snow, it tends to melt within a few days.

River temperatures vary throughout the year.  Temperatures range from near freezing to over 70 degrees in the summer months.  Due to rapids, rocks, and hazardous currents, swimming and wading are prohibited at all times.