[BrianL99]

Originally Posted by Arctic Fox

I have been using the weather.com website for years and, at this time of year, they always start off by predicting a high chance of rain in the afternoon which, quite often, drops away dramatically

For example, at 3pm this afternoon (2pm in brackets) they showed the following chance of rain:

5pm - 41% (76%)
6pm - 71% (98%)
7pm - 79% (98%)
8pm - 71% (68%)

so, in the space of an hour, their prediction for rain at 6pm and 7pm dropped from a confident "almost certain" 98% to considerably less.

To put it another way, their prediction of "no rain" at 6pm has soared from 2% to 29%!

This is a fairly simple synopsis of how that "percentage" is calculated. It is a different than most folks assume.


How our meteorologists calculate rain percentages and what it means