BRN 9-2 (uncompressed) - Flipbook - Page 72
Monsoon Rainfall in Hillsboro
The chart above records the precipitation which occurred in Hillsboro
during the monsoons (June 15September 30) from 1935 to 2025.
The average (mean) amount of
precipitation over that period was
7.08Ó. The median precipitation level
was 6.85Ó. The minimum amount of
precipitation occurred in 2011 (1.64Ó)
and the maximum amount was in
2006 (14.15Ó).
June 15-30: The average (mean)
amount of rain between 1935 and
2025 (inclusive) was .56Ó during the
last half of the month; the most rain
fell in 2000 (3.85Ó) and in several
years there was no recorded rain.
July: The average (mean) amount of
rain between 1935 and 2025
(inclusive) was 2.19Ó; the most rain
fell in 1962 (5.65Ó) and the least in
2023 (.03Ó).
(inclusive) was 2.35Ó; the most rain
fell in 1993 (7.93Ó) and the least in
1942 when there was no rain.
September: The average (mean)
amount of rain between 1935 and
2025 (inclusive) was 1.98Ó; the most
rain fell in 1975 (7.11Ó) and the least
in 1953, 1954, 1955, 1959, and 1998
when there was no rain.
If the 9 years with the greatest
amount of rainfall during the
monsoon (10% of the total years) are
removed from the assessment then
the average (mean) amount of rainfall
during monsoon drops to 4.58Ó.
If the 9 years with the least rainfall
during the monsoon (10% of the total
years) are removed from the
assessment then the average (mean)
amount of rainfall during monsoon
only increases to 7.60Ó.
The average (mean) amount of rainfall
during this period is skewed upward
August: The average (mean) amount
of rain between 1935 and 2025
71
by those years when there is
signiÞcantly more rain than usual.
We live in a dry environment, and
small amounts of rain can make a big
difference in how the fauna (including
humans) and ßora of our area thrive
or donÕt. When periods of low
precipitation occur over several years
in sequence the effect on fauna and
ßora is compounded and is much
greater than the effect of a single year
of low water.
Precipitation during years of more
rainfall sometimes occurs in singular
events. When this happens not only
do we experience ßooding but we
lose the advantage we could have
gained from that amount of water if it
had been spread out over a longer
period.
Here is looking forward to this yearÕs
monsoon. Special thanks to Russ
Bowen (Hillsboro) for the data and
analysis.
