WeatherWhys Blog

Summer is Coming to an End

Summer is Coming to an End

The astronomical end of summer is almost here. That happens later this week at the Autumnal Equinox (8:09 PM on Wednesday evening). “Equinox” is latin for “Equal Nights”. Coincidentally, the Harvest Moon will be full that night AND it is the official start of the Great Kern County Fair. The seasons.. they are a-changin’.

For the period June 1 – September 19, 2010 Bakersfield has averaged 0.1 degree above normal, which is statistically normal. July ended up with slightly above normal temperatures. August and September were below normal just a bit. The last time we saw measurable rainfall in Bakersfield was May 28th (.01”). Monday represents the 115th day without rainfall, although a trace of rain fell on July 11th. That is nowhere close to the record period without measurable rainfall, which is 211 days from March 2 to September 29, 1966.

A lot of people have been asking me lately when I might put out my “No More 100s” forecast. While summer is winding down, we have still seen 100-degree heat as late as October 17th in Bakersfield. I believe there will only be one more threat for that kind of heat and it comes up next weekend. Following a couple of cold fronts early on Monday and another one on Wednesday, high pressure will strengthen again. Computer models take us back into the 90s for about a 4-day period. It is too soon to see if the proper alignment of strong ridging aloft and sufficient easterly winds on the ground may develop for triple digits. Sometimes a Santa Ana wind scenario comes about in October and November bringing howling northeasterly winds to the LA area with 100-degree heat. Occasionally, we will also see triple digits when some of those winds become southeasterly in the San Joaquin Valley. However, medium range computer models are strongly suggesting that October will feature more troughs of low pressure than hot ridges- Consequently that bodes for cooler weather. So I have focused on the upcoming warm period from about Friday of this week through Monday of next as the last gasp of super heat in Bakersfield for 2010.

I issue the Fab Four Forecasts each year: 1) No more 110s, 2) No more Heat Waves, 3) No more 100s, and finally 4) No more 90s. Since 1990 they have never been wrong. The first one this season was issued on August 26th after our highest reading of the year the day before at 111. The second forecast was issued earlier this month on September 6th following Heat Wave #4 which lasted 4 days, had a peak temperature of 103 and was rated a category zero heat wave. Only Heat Wave #3 during the last week of August rated a category one heat wave due to excessively high temperature and humidity. (Defined heat waves are rated from zero to 5 based on a number of parameters. The worst in recent memory was Heat Wave #3 of July 2006 in which Bakersfield hit 112 degrees with 6 record  temperatures. This heat wave lasted 16 days and was blamed for millions of dollars in agricultural damage throughout central California. It was rated a category 4 heat wave). Heat Wave #2 was the longest one of 2010, lasting 12 days in the middle of July. The very first Heat Wave #1 took place 4 days at the end of June. Only during Heat Wave #3 in August did we break or equal any high temperature records (2 highs and 1 record high minimum).

If we can make it through the first weekend of the Fair I think we may not have to deal with 100s again until next year. All things considered, this has not be a particularly bad (hot) summer in Kern County. My winter 2010-11 forecast is calling for slightly below normal rainfall. We should not return to severe drought conditions, which ended last winter. I am also expecting temperatures to average near normal, with perhaps 2 separate extended periods of very cold weather between November and March including widespread freezing conditions. Additionally, I am predicting more dense fog days this winter than previous ones. So enjoy the last hot blast and get ready for cool weather. Soon it will be cold and you may be wishing for those balmy hot days of summer to come quickly with their Bar-B-Qs and swimming pools.