Weather Blog

Seattle sets all-time record high pressure reading

Seattle sets all-time record high pressure reading

We've managed to set a record...for calm weather.

Early Thursday morning, Seattle recorded a sea level pressure of 1043.4 milibars, or 30.81" of mercury, breaking the old record for highest pressure ever recorded at Sea-Tac Airport at 1043.0 mb set Jan 28, 1949.

The highest pressure reading ever recorded in Seattle was 1043.9 milibars (30.83") at the Downtown Federal Building almost exactly 90 years ago, on Dec. 3, 1921.

You might think summer time and its abundant sunshine would be when we set our high pressure records, but all the top readings are in December and January. Why?

Cold air is much more dense than warm air, so when we get a big pool of cold air, it is usually associated with very high pressures.

The high pressure system involved with our record wasn't unusual in that it had a central reading of 1046 mb, only that it was centered much closer to home -- just on the Canadian side of the border north of Vancouver. Typically these highs roost over toward the interior of B.C. or western Alberta.

That said, our all time lowest pressures are in the fall and winter too, coinciding with strong wind storms. Seattle's all-time lowest pressure recording is 970mb or 28.65" recorded during the Dec. 12, 1995 windstorm.

This amazing high pressure over the Northwest is contributing to the wind problems in the southwest as there is a very large difference in pressure between there and here now. v By the way, I would be interested to hear if anyone is noticing any physical effects.

I wrote this blog coincidentally about how changes in pressure can have physical effects to post Thursday and while I mentioned that joint pains were typical when we get large pressure drops with approaching storms, I'm curious if you noticed as the pressure rose rapidly with this approaching high pressure system?