On Sept. 23, the sun will be directly above the Earth’s equator, resulting in the end of summer and the beginning of fall. Even with the shorter days and less autumn sunlight, the beaches and coastal valleys of San Luis Obispo will probably be warmer this fall than this past summer.
For those of us who live along the coastal regions of San Luis Obispo County, it will come as no surprise that temperatures for August were cooler than normal.
August temperatures never even reached the 70 degrees mark in Los Osos. In fact, Los Osos hasn’t seen 70 degrees since May 5.
Farther inland, San Luis Obispo usually averages 66.1 degrees during August, but this year, it only averaged 60.7 degrees or about the same as 2010, which averaged 60.9.
In the North County, temperatures were closer to normal. Paso Robles averaged 72.7 degrees this August compared to last year’s 71.8 degrees. The normal for August in Paso Robles is 73.2.
The majority of locations in California were cooler than normal this August. However, east of the Rockies, temperatures have been running well above normal with many regions breaking temperature records.
No other place in the country has suffered more from the heat than Texas. This August was the hottest month on record in many parts of the state. The Dallas/Fort Worth area averaged 93.4 degrees this August, its warmest month ever.
More astounding were the overnight highest minimum temperatures. This August averaged 82.5 degrees. The next warmest August on record occurred last year, which averaged 79 degrees. In a hundred-plus years of weather records, the all-time high minimum temperature for Dallas was 85 degrees. So far this year, it has tied or exceeded that 10 times. In other words, something that has only happened once before in all those years has met or exceeded that 10 separate times so far this year!
To make matters worse, Texas is caught in the grip of a devastating drought. Wildfires have nearly burnt 31⁄2 million acres across the state. A bale of hay in Texas is selling for more than $70. In San Luis Obispo County, it coast $19 for a bale of alfalfa, according to Farm Supply Company. At these prices and without any ground foliage, Texas ranchers are being forced to sell their livestock; they simply can’t afford to feed them.
In North Texas these days, cattle auctions run into the early morning hours selling thousands of head of cattle. Fortunately, the international demand for meat is keeping the price of beef high.
However, the same can’t be said for horses, which are being given away or tragically abandoned.
Combined with failures of crops such as cotton, Texas agriculture has lost more than $5 billion and counting. Many residents are actually hoping for a tropical storm or hurricane to provide much needed rain.
So what happened to summer? Like last year, it was a combination of several factors.
The jet stream buckled over the West Coast, producing a series of upper-level, low-pressure troughs along the coast. The troughs decreased the amount of subsidence, or sinking of the air mass, that normally occurs during the summer. That, in turn, allowed a deeper marine layer to develop and persist. Over Texas, the jet produced a strong ridge of high pressure.
Also, persistent northwesterly winds produced an unusually great amount of upwelling and, combined with a La Niña (colder than normal ocean water in the equatorial and eastern Pacific) condition, helped to produce unusually chilly seawater temperatures along the immediate shoreline, cooling the air above it.
Warmer weather could be on the way. Typically during the fall, an area of high pressure builds at the surface over the Great Basin — the area between the Sierra Nevada range to the west and the Rocky Mountains to the east — and begins to dominate our coastal weather.
This condition usually produces northeasterly (offshore) winds, especially during the night and morning hours. These winds bring the relatively dry air to our shoreline, pushing the marine layer far out to sea, which produces sparkling, clear visibility along our beaches and warmer temperatures.
This morning’s mist and drizzle in the coastal valleys and along the beaches may produce measurable precipitation at a few of the coastal weather monitoring stations. Elsewhere, clear and sunny weather will welcome us this morning.
The northwesterly winds will begin to pick up this afternoon, producing some clearing along Avila Beach and Cayucos.
In other words, these northwesterly winds will descend down the Irish Hills (compressional heating) and should produce partly to mostly sunny skies for the Pops by the Sea “Summer of Love” concert.
Temperatures at Avila Beach will start out in the 50s during the morning hours under overcast skies. Temperatures will rise to the low to mid-60s by the afternoon under partly to mostly clear skies. If you’re attending this event, a light jacket or sweater may be a good idea.
The northwesterly facing beaches (Cambria, Morro Bay, Montaña de Oro and Nipomo) will remain mostly overcast with temperatures ranging from the high 50s to low 60s. The coastal valleys (San Luis Obispo) will reach the mid-70s while the North County (Paso Robles) will reach the mid- to high 90s.
Coastal low clouds, fog and drizzle will surge back into the coastal valleys later this evening through Monday morning.
Apart from these typical late summer weather conditions, there are some chances for afternoon thunderstorm development in the central and southern Sierras today through Labor Day.
A high-pressure ridge is expected to build over the West Coast on Tuesday, leading to gradually warmer temperatures and fewer coastal clouds during the night and morning hours. The hottest days look to be Wednesday or Thursday as afternoon temperatures climb to the low 70s at the coast, mid-80s in the coastal valleys and high 90s in the North County.
As the high-pressure ridge begins to weaken and shift east late this week, gradually cooler temperatures are expected for next weekend.
Note: A few of the models are advertising monsoon moisture streaming northward over our area on Saturday and Sunday.
Today’s surf report
Arriving from the Northwest:
Today’s 3- to 4-foot northwesterly (310-degree deepwater) swell (with an 8- to 10-second period) will continue at this height and period through Monday morning.
Increasing northwesterly winds will generate a 3- to 4-foot northwesterly (290-degree deepwater) sea and swell (with a 5- to 14-second period) along the coast Monday afternoon through Wednesday.
A 978-millibar storm near the Aleutian Islands will produce a 4- to 6-foot northwesterly (290-degree deepwater) swell (with an 11- to 14-second period) along the Pecho Coast on Thursday and will remain at this height but with a gradually shorter period through Saturday.
Arriving from the Southern Hemisphere:
Today’s 2- to 4-foot Southern Hemisphere (200-degree deepwater) swell (with a 14- to 16-second period) will gradually decrease to 2 to 3 feet by tonight.
This swell will continue to lower to 1 to 3 feet (with a 13- to 15-second period) on Monday.
A 1- to 3-foot Southern Hemisphere (180-degree deepwater) swell (with a 16- to 18-second period) is forecast along the coast Wednesday through Saturday.
Seawater Temperatures: Seawater temperatures will range between 54 and 57 degrees through Wednesday, increasing to 55 to 59 degrees on Thursday through next Sunday.
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John Lindsey, media relations representative for PG&E and local weather expert, has lived along the Central Coast for more than 25 years. To subscribe to his daily weather forecast or ask him a question, email him at firstname.lastname@example.org.