Severe Thunderstorms and Heavy Rain in the Central Plains to Upper Midwest; Extreme Heat in Parts of the South

Thunderstorms with severe wind gusts and hail will be possible today across parts of the central Plains, and from the Missouri Valley into the upper Mississippi Valley. Heavy rain associated with the thunderstorms may also produce flash/urban flooding. Critical fire weather conditions expected in the Great Basin and interior Northwest. Dangerous heat continues across the Southwest and Southeast. Read More >

The fall equinox this year is on Monday, September 22nd at 1:19 pm CDT.

The word "equinox" comes from the Latin term meaning "equal night". Despite this, the length of day and night is not quite the same on this date. Why not? While the geometric center of the Sun is above the horizon for 12 hours, sunrise is defined as when the edge of the Sun's disk becomes visible, not when the center of the Sun is visible. The atmosphere also causes the light to bend ("refraction"), affecting when the Sun starts to be seen versus when it actually crosses the horizon. The combination of these factors will cause the equal day-night (known as "equilux") to vary by latitude.

Typically, the equinox occurs around September 22-23 each year. Around our latitude, the date of equal day and night is September 25th this year.

Why do we have seasons? Image courtesy of NASA

(Image courtesy of NASA)

ILX RSS Feed

Severe Thunderstorms and Heavy Rain in the Central Plains to Upper Midwest; Extreme Heat in Parts of the South

Autumn Begins at 1:19 pm CDT Monday