Scattered Severe Thunderstorms Across the Northern Plains; Fire Weather Concerns in the Western U.S.

Scattered severe thunderstorms are forecast across central and eastern North Dakota, as well as far northwest Minnesota Saturday (Slight Risk level 2 of 5). Damaging wind gusts are the primary threat. Elevated to critical fire weather conditions will persist through the weekend across the Western U.S. Isolated dry thunderstorms could lead to new fire starts over portions of the northern Rockies. Read More >

For a complete listing of the dates of the winter and summer solstice's and spring and fall equinox's through 2020, check out this site from the U.S. Naval Observatory.

The Seasons

We all know that the Earth makes a complete revolution around the sun once every 365 days, following an orbit that is elliptical in shape. This means that the distance between the Earth and Sun, which is 93 million miles on average, varies throughout the year. During the first week in January, the Earth is about 1.6 million miles closer to the sun. This is referred to as the perihelion. The aphelion, or the point at which the Earth is about 1.6 million miles farther away from the sun, occurs during the first week in July. This fact may sound counter to what we know about seasons in the Northern Hemisphere, but actually the difference is not significant in terms of climate and is NOT the reason why we have seasons. Seasons are caused by the fact that the Earth is tilted on its axis by 23.5°. The tilt's orientation with respect to space does not change during the year; thus, the Northen Hemisphere is tilted toward the sun in June and away from the sun in December, as illustrated in the graphic below.