Summer officially arrives today

Posted at 1:02 PM, Jun 20, 2016

WEST MICHIGAN — So the unofficial start to summer is Memorial Day weekend. The meteorological start to summer is June 1. But the astronomical and official start to summer here in the northern hemisphere is Monday June 20. What’s the difference? The official start is tied to the position of the sun. On the summer solstice, as it’s called, the sun is as far north as it will ever be. The rays are quite intense, the sun appears high in the sky (actually over the Tropic of Cancer), and the longest day of the year occurs with more than 15 hours of daylight. Recall that our “seasons” are due to this 23.5 degree tilt of the earth. We’re currently the farthest away from the sun that we are all year (technically in July), but the 23.5 degree tilt gives us more direct rays overhead and therefore warmer temps. The time the sun is at that position and summer begins is 6:34 P.M.

Compare those long days to the shortest day of the year in winter where we generally only see about eight hours of daylight. Here’s the bad news! If this marks the longest day of the year, we have nowhere to go but down from this point on. That means the days will now start to get shorter and we will actually lose daylight each day between now and the winter solstice in December. At first it will be slow, but we’ll eventually lose about two to three minutes of “light” each day in a couple of months.

Our summer solstice also marks the start of winter for the southern hemisphere…their winter solstice. In case you ever wondered why we have our warmest days AFTER the start of summer, it’s due to the seasonal temperature lag the earth undergoes. In April, May, and June the northern hemisphere is still cold and just completing winter. It takes time for hemisphere to heat up and attain its warmest temperatures, which typically don’t happen until July and August…it’s a seasonal temperature lag.

As I’ve noted before in a posting a few months back, this summer is slated to be somewhat hot and dry above the norm. So far, it hasn’t disappointed. Grand Rapids has already had a handful of 90+ degree days and it’s only mid June. Get the complete forecast at