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Extreme Rainfall Events In The USA

November 16, 2012

By Paul Homewood


NOAA have a useful website for keeping track of state records for temperature, rainfall etc. One of the parameters is for “24 hour precipitation”. These are for discrete 24 hour periods, and not specifically “daily records”.

We often hear, of course, that extreme weather is on the increase, and certainly heavy rainfall is commonly referred to as an example. So what do NOAA’s figures actually say?




It appears that the 1990’s claim the record for most state records with 10. By contrast the latest decade seems to be perfectly normal with just 4 records set – Minnesota, Nevada, Oregon and South Dakota.

The early years in the record are, I suspect, not comparable because of a lack of reporting stations and a lack of detailed hourly recordings in many of the stations that did exist. But comparison with post war records show clearly that heavy rainfall events have, if anything,  declined.

Once again, alarmist claims simply do not stand up on examination of the facts.




The NOAA list is here –

  1. November 16, 2012 9:45 pm

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  2. Robin permalink
    November 17, 2012 11:14 am

    Hello, Paul, I’m not sure that I understand these “New Records” plots. The fact that there are always new records must mean that the parameter of interest has exceeded a previous record, and that somewhere there has been a change – up or down – that says something about the history of the parameter. If things were not changing anywhere the number of new records would presumably be zero. Have I got my thinking in a twist? Anyway, I suggest that such plots are not really very informative! I would prefer some other concise index of change, but suspect that there may not be one that everyone would believe in.

    Thanks again for you blog. I enjoy reading it.


    • November 17, 2012 1:53 pm

      Hi Robin,

      These are all time records (or at least since 1895!). So, for instance, eight states had their highest rainfall records set in the 1970’s. The plots therefore do not show if they had set a previous record in an earlier decade.(i.e. only one record per state is shown).

      What the figures do show is that extreme rainfall events today are not as common as in past decades.

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