This Monday, at 7:29 p.m., the sun will be directly above the Earth’s equator, resulting in the end of summer and the start of fall.
As we move into autumn, the days will continue to get shorter until the first day of winter on Dec. 21, which is the shortest day of the year.
Temperatures become cooler in the North County during fall, while temperatures along the beaches can actually be warmer due the increased amounts of Santa Lucia (offshore) winds and less fog.
You see, we live in a county with many microclimates, which become especially prevalent during the fall season. As we move into fall, the Santa Lucia (northeasterly-offshore) winds and northwesterly (onshore) winds battle for supremacy. The back-and-forth scuffle can produce hot temperatures in the late morning and then cool temperatures in the afternoon — in the same locations. That’s why a lot of us keep a sweater handy.
By the way, the wind direction is reported from where the wind originates. The wind direction is usually reported in cardinal headings. For example, northeasterly winds are from the northeast and blow toward the southwest. Because of compressional heating as these winds descend the Santa Lucia Mountains, they can become hot and dry as they move out to sea.
Speaking about warm temperatures, 2014 is still on track to be the warmest year in California’s history since record-keeping began in the late 1800s. The first eight months of 2014 were the hottest ever in California, according to the National Oceanic and Atmospheric Administration (NOAA). In fact, it was 4 degrees warmer than average.
These above normal temperatures have exacerbated the current record drought and may produce the worst wildfire year in California’s history.
Locally, the Paso Robles Airport maximum temperature averaged 81.7 degrees from January through August this year. Normally in the North County, the high average is 76.8 for this time frame, or 4.9 above normal.
Closer to the coastline, San Luis Obispo County Regional Airport high temperature has averaged 74.6, or 5.1 degrees warmer than the historical mean. At the ocean, air temperatures at PG&E’s Diablo Canyon power plant have averaged a record 5.5 degrees above normal.
If you recognize a pattern of warmer normal temperatures as you get closer to the coastline, you’re right. This can be attributed to near record-breaking seawater temperatures in the Eastern Pacific ocean. So far this month at Diablo Canyon, the seawater temperatures have been around 61.1 degrees, the warmest September on record since 1983, which averaged 62.5. Normally, seawater temperatures average 57.5 degrees at this time of year.
For most of the year, the abnormally warm ocean temperatures have not affected the atmosphere in a classic El Niño pattern. However, Jason Samenow (Capital Weather Gang's chief meteorologist and the Washington Post's weather editor) reported last week that “researchers at the International Research Institute for Climate and Society said borderline El Niño conditions have developed.
The initiation of El Niño is a move in the right direction for enhanced rainfall in California this winter. But as weak El Niño events don’t always deliver generous rains, the Golden State needs to root for it to strengthen.
As I’ve written earlier, another large-scale ocean water temperature cycle in the Pacific could provide another important clue to what this winter will bring. This large-scale cycle is the Pacific Decadal Oscillation (PDO). The phases of the PDO are called warm or cool phases. Unlike El Niño and La Niña events, which last only about a year or so, the PDO stays in one phase for a much longer period.
Since 2008 through the end of 2013, the PDO has been mostly in the cool phase. This past January saw the PDO gradually change to a positive phase. Since March, the phase has shifted solidly to positive. Since 1950, a positive phase of the PDO combined with El Niño usually produces normal to above-normal rainfall along the Central Coast.
These are long-range forecasts and there are no guarantees. Only time will tell the story, but with each passing day, I do feel more confident that will we receive normal or even above normal amounts of rainfall this year.
Did you know that PG&E delivers some of the nation’s cleanest power? More than 50 percent of the electricity the company provides to customers comes from sources that are renewable and/or emit no greenhouse gases.