Summer is a great season in North Idaho, even with occasional periods of scorching triple-digit temperatures. It is often said that Labor Day weekend is the unofficial end of summer, but does the first week of September mark any real meteorological changes that would redirect our thoughts to the fall season? Up until the last couple of days, we had seen above-normal temperatures and bone-dry conditions. It seems now that the winds of change have blown in. Let’s take a look at some statistics of the season, which won’t officially end until 9:03 p.m. Sept. 22.
Most people relish the long hours of sunlight in the summer. Ironically, the longest day is the very first day of summer, the solstice, on June 21, when we receive about 16 hours of sunlight. We start losing minutes of daylight each day after that, while average temperatures, on the other hand, continue to rise.
Summertime starts with an average high temperature of 76 degrees. The heat climatologically peaks at the end of July into August, those “dog days of summer,” with average highs in the upper 80s. It is rare, however, to have an “average” day, and, as you may recall, we spent most days in the months of July and August on the warmer side of average, with long stretches in the 90s and several 100-plus-degree days.
I would say that it really doesn’t “feel” like summer unless you have high temperatures at least in the 80s, but by Sept. 1, the average high in Coeur d’Alene slips to 79 degrees. On the last day of summer, the average high temperature is in the lower 70s, and on the autumnal equinox, we’re down to 12 hours of daylight. But even then, can you be sure that 80- and even 90-degree days are a thing of the past? You can always root for the extremes … which is where the averages are derived from anyway. The latest 90-degree day for Coeur d’Alene on the record books is Sept. 26, which happened back in 1963, whereas we’ve reached 80 degrees as late as Oct. 18 back in 1974. That kind of warmth that late in the season might bring another term to mind, the “Indian summer.”
For those of us who still aren’t ready to put away the shorts and sandals even by late October, there is the hope of “Indian summer.” Though the origin of the term is uncertain, it has appeared in writings as early as the late 1700s. The Glossary of Meteorology defines Indian summer as “a period, in mid- or late autumn of abnormally warm weather, generally clear skies, sunny but hazy days, and cool nights.”
In some parts of the country, an abnormally warm period in late autumn is not considered a true Indian summer unless it is preceded by the first frost or freeze. Last year, Spokane didn’t see its first subfreezing temperature until the first week of November. There was no Indian summer after that, as temperatures trended downward at a pretty steady pace. Coeur d’Alene felt the chill a bit earlier, first dipping below the freezing mark on Oct. 9. Daytime highs for the remainder of that month lingered pretty close to normal, though with no subsequent warm spell.
For the last official week of summer 2006, it does look like more seasonable weather is finally going to take hold. Say goodbye to 90-degree readings (you’re probably ready for that anyway) and welcome the needed rain. Believe it or not, we could be talking about snow by next month!