Today is the last day of ‘official’ summer. Tomorrow Autumn begins at 2:49 a.m. Astronomically, the September equinox is the autumnal, or fall equinox marking the end of summer and the beginning of fall (autumn). The fall season ends on the December solstice when astronomical winter begins.
While the September equinox usually occurs on September 22 or 23, it can rarely fall on September 21 or 24. A September 21 equinox has not happened for several millennia. However, in the 21st century, it will happen twice—in 2092 and 2096. The last September 24 equinox occurred in 1931, the next one will occur in 2303.
The equinox dates vary because of how the Gregorian calendar defines a year (365 days) and the time it takes for Earth to complete its orbit around the Sun (about 365 and 1/4 days).
This means that each September equinox occurs about 6 hours later than the previous year’s September equinox. This eventually moves the date by a day.
The term equinox comes from the Latin words aequus, meaning equal, and nox, meaning night. This has led to the common misconception that everybody on Earth experiences equal day and night—12 hours of daylight and 12 hours of night time—on the day of the September equinox.
In reality, most places on Earth enjoy more than 12 hours of daylight on this day. This has two reasons: the way sunrise and sunset are defined and the atmospheric refraction of sunlight.
Locations that are not on the equator do get to experience equal day and night twice a year, usually a few days before or after the equinoxes. The dates for this event, which is also known as equilux, depend on a location’s latitude—those south of the equator celebrate it a few days before the equinox, and people in the Northern Hemisphere reach the equilux a few days after the equinox.
Today will still feel like summer with a mix of sun and clouds and isolated showers or storms possible. Highs will be near 80°.
Grand Rapids Forecast
9 22 grrU.S.A and Global Events for September 22nd:
1810: A tornado striking Fernhill Heath had a width between 0.5 to 1 mile; making it the widest path ever in Britain.
1890: A severe hailstorm struck Strawberry, Arizona. Five days after the storm hail still lay in drifts 12 to 18 inches deep.
2006: The tristate area of Missouri, Illinois, and Kentucky was struck by the worst tornado outbreak in recorded history during the month of September. One supercell produced a long-track F4 tornado across southeastern Missouri into southwestern Illinois. This tornado traveled 27.5 miles.
Forecast Discussion
Dry conditions will dominate the short term period through Saturday. With stronger low level E/SE flow today, it is a bit tougher to envision much of a lake breeze developing. The GEM typically is the most aggressive with these scenarios, and indeed is showing more of a lake breeze with surface convergence to help pop a few isolated showers in model precipitation output. However, I suspect this is overdone, and if you look at the 00z suite of CAMs you will find little if any support for showers or storms today. The 00z HREF does hint at very isolated showers and a potential thunderstorm possible especially across northern Lower Michigan as the remnants of the upper low get washed out in the more dominant upper ridging across central and eastern Great Lakes. However, even the typically moist Nam3km has a pretty dry layer between 850mb-600mb that will likely prevent much from developing. It is just not worth putting in the forecast given the isolated and sparse coverage of anything that may happen to develop, with <15% likelihood. Today into Saturday should feature mostly sunny skies. Ensemble guidance continues to trend/point toward a predominately dry forecast going into next week. The number of members producing measurable precip continues to shrink with each run. The nrn Plains upper low gets sheared out by the strong upper high near Hudson Bay early next week as it moves to the southeast. Some semblance of this upper low/shear zone will probably still be present though near or just south of MI through most of the week. However the persistent feed of low level dry air from the east will limit precip potential and the main impacts from that upper low should be just for considerable mid and high level cloudiness at times. Guidance also continues the theme of cooler high temps around 70 most of next week. This is also related to the continued low level easterly flow around the strong 1035 mb sfc high that will be situated to our northeast.
The sun is out but getting a good shower. The temperature was 80 but now has dropped to 72.
Slim
Feels more like a July day than a late September day. Tomorrow we leave for Estes Park Colorado, can’t wait to feel the crisp mountain air!
Last day of summer! Fantastic, because no more heat and humidity! I love cool summers! Incredible!
Temps in the 70’s lows in the 50’s sunset 8pm trees turning colors dosent get any better then this weathereise love it Happy Fall!! INDY
For the time of year, this is awesome, but when winter hits bring on the snowstorms!!!
Yesterday was a warm summer like day with the official H/L of 80/58. There was no rain fall and the sun was out 41% of the time. For today the average H/L is 72/51 the record high of 95 was in the heat wave of 2017 and the record low of 33 was in the long cold snap at the end of September 1976 when there were 10 of 11 nights with lows in the low 40’s to the upper 20’s with lows of 29 on the 24th and 32 on the 28th The record rain fall amount of 3.14”… Read more »
Today looks to be the last of the warms days for a while as highs will be near 80. The rest of the next week will see highs in the mid 70’s over the weekend then dropping to the uppers 60’s to low 70’s Lows will be mostly in the low to mid 50’s There does not look to be much in the way of rain fall.
Slim
Last year we had a very chilly ending to September and a slightly earlier leaf change than recent years. I’m thinking with the warm ending to September this year (and probably warm fall?) the leaf change will be later this year