Calcium Products - Fog Days
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Fog Days

Have you heard the old saying “90 days after a fog you can expect precipitation”? Are you a fog day counter? Is there any scientific backing to it?

My grandmother counted fog days and said more often than not they were right. I too have counted them and I would say they are accurate to within 3-5 days.
According to the NOAA:
In looking where this statement “it rains 90 days after fog” comes from, the search only found two statements that where similar, however both where for winter snowfall not rain. However, they seem to be related. The other two statements are “the more fog in August the more snow in winter” and “for every fog in August, there will be a snowfall in the winter.” All three statements relate the occurrence of fog with precipitation in the next season. And these all seem to originate from Ben Franklin.
In a study they conducted in Montana, in looking at the past several years of observations in Glasgow (January 2000 to July 2006) there is precipitation (rain or snow) 1 out of every 4 days, about 25% of the time. Looking over the same period of time it snowed or rained 90 days after fog about 27% of the time. The difference between the two is very slight and statistically the difference is small, thus the statement that it rains 90 days after fog is really no better than saying it will rain 90 days after today or 90 days after the first robin appears.
So is counting fog days reliable?
Well not according to this study, but I observed that the whole month of August 2009 was foggy in Gilmore City and the whole month of Dec was snowy. So far it has been foggy every day this week, which according to the myth, the first week of June will be wet.
In an article today from the Bismarck Tribune:
Tuesday was the year’s 68th day. Of those 68 days, fog was reported in Bismarck on 54 days. On 17 days, the fog was considered “dense.”  
Which if you are a fog day follower could indicate another cool wet year.
If you have counted fog days, I’d love to hear your thoughts. Whether there is truth to fog day or not, hopefully all this talking about the fog will help it go away, I am ready for the sun and spring to get here!

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  • Article Reference:: Calcium Products, Inc.
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