Posted September 21, 2008, 6:33 PM.

The value for each month is based on all of the years of data for that month, up to and including the current day. The value includes the current day, so it may change dynamically as rainfall is recorded.

Looking at the averages by month, you'll notice large values for October for many of the sites that are old enough to record an unusually wet October in 2004. Remember that only a few years are represented here and that these values will grow more accurate over time.

During the past summer, average seasonal precipitation values were added to the precipitation page of each weather site. This page tallies rainfall by season. The average values there do not include any incomplete seasons, nor do they include the current rain season.