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Harris-Mann Climatology Article Archive

Title: The Effects of 'Lunar Cycles'

Author: Climatologist Cliff Harris
Published: 1/23/2015

As previously mentioned in ‘Gems,’ we’ve said that many of our long-term forecasts are based on lunar cycles.

Have you ever noticed that much of our coldest weather in the winter and our hottest temperatures in the summer have occurred near a ‘full moon’ cycle? The major weather change that led to the record snows and frigid temperatures in early January occurred during the recent ‘full moon’ phase.

No one will argue that during a full moon, high tides are created because the Earth and its satellite are attracted to each other, like magnets. The gravitational pull of the moon results in high tides that are higher than normal. If the moon can affect "tides of the water," then why is it unreasonable to claim that they likewise alter "the tides of the air?"

From our research, the upper-level jet stream winds tend to become more meridional, or north-to-south, during both the full moon and new moon lunar phases, especially the full moon. High pressure systems will often intensify bringing our region the hot weather in the summer and frigid temperatures in the winter. During that same cycle, low pressure areas also become stronger, which often leads to bigger storms like our big snows in early January of 2015.

But, when we’re in a first quarter or last quarter cycle, however, the jet stream will often become more zonal, or west-to-east. Although we may see active weather during either a first quarter or last quarter lunar phase, conditions are generally milder and drier. Storms moving in from the Pacific Ocean will typically ‘fall apart’ by the time they enter our region on the east side of the Cascade Mountains..

Our best chances for moisture are during either the new moon or full moon lunar phases. Conditions tend to become wetter, especially during a milder than normal ‘new moon’ cycle. Storm systems seem to intensify during these occasions. Lunar cycles are not perfect, but they usually work about 70 percent of the time. Farmers have planted and harvested by the lunar cycles for thousands of years.

Of course, there are other factors that determine a long-term weather forecast. Sea-surface temperatures, sunspot activity and other short and long-term climatological cycles will often shape our weather pattern.