The Santa Ana winds are notorious for exacerbating wildfires in southern California.
These strong winds blow warm, dry air across the region at different times of the year, but mainly occur in the late autumn. They form when a large pressure difference builds up between the Great Basin – a desert that covers most of Nevada and parts of Utah – and the coastal region around LA. This pressure gradient funnels air downhill and through the passes of the San Gabriel and San Bernardino mountains toward the Pacific. According to the NWS, the Santa Ana winds can easily exceed 40 mph.
Originating in the high desert, the air starts off cool and dry. But as it travels downslope, the air compresses and warms. In fact, it warms about 5°F for every 1000 feet it descends. This dries out the region’s vegetation, leaving it susceptible to any type of spark. The fast-moving winds then fan the flames of any wildfires that ignite.
The Santa Ana winds are named for Santa Ana Canyon in Orange County, CA.
The winter solstice is still a few weeks away, but meteorological Fall (September, October, and November) has officially ended and it was the fourth warmest on record in New York City.
The season, a transitional period between summer and winter, can often feel like a temperature roller coaster. This year, highs ranged from 91°F to 38°F. In the end, though, the warmth came out on top. The city’s average temperature for the three months was 60.4°F, which is 2.9°F above normal.
In all, fifty-nine days posted above-average readings and two of the season’s three months were warmer than their long-term norms. In fact, October 2017 was the city’s warmest October on record.
This autumn was dominated by a pattern of warm spells separated by a few short-lived blasts of cold air. It was largely driven by the jet stream staying well to the north for most of the season with just a few dips southward.
The city’s warmest autumn on record, according to the NWS, occurred in 2015, which tied 1931 with an average temperature 61.8°F. The coldest was 1871 when the three-month average was only 51.7°F. Central Park weather records date back to 1869.
Credit: The Weather Gamut
September 2017 felt like a temperature roller coaster in New York City. Highs ranged from an unseasonably cool 66°F to a record warm 91°F. But with eighteen of the month’s thirty days posting above average readings, the heat won out in the end. The city’s mean temperature for September was 70.5°F, which 2.5°F above average.
In terms of precipitation, the month was mostly dry. Only 2.0 inches of rain was measured in Central Park, marking the third month in a row to deliver below average rainfall. The city usually gets 4.28 inches of rain in September.
Credit: The Weather Gamut
The season officially changed to autumn over the weekend, but it felt more like summer in New York City.
The temperature in Central Park hit 87°F on the equinox. Then on Sunday, it soared to 91°F, setting a new record high for the date. The previous record of 89°F had been in place since 1959.
At this point in September, temperatures usually peak in the lower 70s. But with a stubborn ridge of high pressure sitting over the region, warm equatorial air is flowing further north than it normally would at this time of year.
If you are ready for autumn, fear not. Temperatures that are more seasonable are expected to return to the city later this week.
Today is the Autumnal Equinox, the first day of fall in the northern hemisphere. The new season officially begins at 20:02 UTC, which is 4:02 PM Eastern Daylight Time.
The astronomical seasons, as opposed to the meteorological seasons, are a product of Earth’s axial tilt – a 23.5° angle – and the movement of the planet around the sun. During the autumn months, the Earth’s axis is tilted neither toward nor away from the sun. This position distributes the sun’s energy equally between the northern and southern hemispheres.
Since the summer solstice in June, the arc of the sun’s apparent daily passage across the sky has been moving southward and daylight hours have been decreasing. Today, the sun appears directly overhead at the equator and we have approximately equal hours of day and night. The word “equinox” is derived from Latin and means “equal night”.
With the sun sitting lower in the sky and daylight hours continuing to shorten, autumn is a season of falling temperatures. According to NOAA, the average high temperature in most US cities drops about 10°F between September and October.
Earth’s solstices and equinoxes. Image Credit: NASA
Our global temperature continued its upward trend last month with November 2016 marking not only the fifth warmest November on record but also closing out the second warmest meteorological autumn ever recorded for the entire planet.
According to a report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for November – over both land and sea surfaces – was 56.51°F. That is 1.31°F above the 20th-century average and only 0.41°F shy of the record that was set last year.
The three-month period of September, October, and November – known as the meteorological autumn in the northern hemisphere – was also one for the record books. With the season posting an average temperature that was 1.39°F above the 20th century average, it was the Earth’s second warmest September to November period on record.
While heat dominated most of the planet these past three months, some places were particularly warm. Here in the contiguous US, the autumn of 2016 was our warmest on record. Nearly every state experienced above average temperatures and eight were record warm – Colorado, Iowa, Kansas, Michigan, Minnesota, New Mexico, Texas, and Wisconsin.
These soaring temperatures are attributed to the long-term trend of human-caused climate change. Whereas El Niño gave global temperatures a boost earlier in the year, it dissipated in June. In fact, its cooler counterpart, La Niña, prevailed across the tropical Pacific Ocean this November.
Year to date, the first eleven months of 2016 were the warmest of any year on record. It is now almost certain that 2016 will surpass 2015 as the Earth’s warmest year ever recorded. Global temperature records date back to 1880.
November felt like a weather roller coaster in New York City this year. We had highs that ranged from a relatively balmy 72°F to a chilly 41°F. However, with 19 out of 30 days posting above average readings, the warmth won out in the end. The city’s mean temperature for the month was 49.8°F, which is 2.1°F above our long-term norm. This was the Big Apple’s 17th consecutive month with an above average temperature – its longest streak on record.
In terms of precipitation, November was unusually wet and marked the first month since July that NYC received above average rainfall. In all, we received 5.41 inches of rain which is 1.39 inches above normal. The majority of this plentiful total fell during two separate heavy rain events. In fact, November 29th was the city’s wettest day of the year and set a new daily rainfall record with 2.20 inches measured in Central Park. Nonetheless, despite these soakers, NYC remains in a moderate to severe drought according the latest report (12/1) from the US Drought Monitor.
November 2016 was NYC’s 17th consecutive month with an above average temperature. Credit: The Weather Gamut
November was the first month since July that NYC received above average rainfall. Credit: The Weather Gamut
Autumn, with its crisp temperatures, is a favorite season for many. But for others, the decreasing daylight hours can bring on a condition known as Seasonal Affective Disorder (SAD).
According to the Mayo Clinic, SAD is a “subtype of depression that comes and goes with the seasons” and is most common in fall and winter. Its exact cause is not fully understood, but researchers say a reduction of sunlight can disrupt the production of serotonin and melatonin – chemicals in the brain that regulate mood and sleep patterns. SAD symptoms include low spirits, lack of energy, difficulty concentrating, and changes in both sleep and eating patterns.
SAD is typically found in places that are far from the equator where daylight is at a minimum in the winter months. A report by the American Academy of Family Physicians says about 6% of the US population suffers from some degree of SAD, with most cases occurring in Alaska.
The most common treatment for SAD is light therapy. This involves sitting in front of a special lamp that gives off light that is similar to natural sunshine. It has been shown to trigger the brain chemicals that regulate mood. The more serious cases of SAD could require advanced talk-therapy or even medication.
While everyone can feel a little “blue” once in awhile, SAD is characterized by a prolonged feeling of depression. It can be a serious condition and should be diagnosed by a medical professional.
The most common type of Seasonal Affective Disorder (SAD) occurs in fall and winter. Credit: hercampus
This autumn has been marked by heavy rain and catastrophic flooding in some parts of the United States. Drought, however, continues to plague large sections of the country.
According to the latest report from the U.S. Drought Monitor, 49% of the nation is dealing with drought. While this number represents a slight improvement for parts of the west, both the southeast and northeast have been drying out.
Currently, 57% of the southeastern US is in some form of drought and 21% is suffering from conditions of extreme drought. These parched conditions, which have been building for months, are now fueling wildfires across the region. According to the US Forest Service, 59 of the 61 active large wildfires burning in this country are in the southeast.
Another hard hit area is the northeast, where 19% of the region is in severe or extreme drought. Water restrictions are in place in parts of Massachusetts and communities in New Jersey are asking residents to conserve water voluntarily.
On the other side of the country, California – now in its fifth year of drought – received some much-needed rainfall recently. However, most of it fell only in the northern counties. Overall, 88% of the Golden State remains in some form of drought with 21% in exceptional drought, the worst possible category.
The Drought Monitor is a weekly publication produced by a partnership of government agencies, including the National Drought Mitigation Center, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration.
Credit: US Drought Monitor
October felt like a weather roller coaster in New York City this year. We had highs that ranged from a balmy 85°F to a chilly 51°F. But, in the end, the warmth won out. The city’s mean temperature for the month was 58.8°F, which is 1.9°F above our long-term norm.
On the precipitation side of things, the city received near average rainfall for the first time in months. In all, we received 4.15 inches of rain in Central Park, which is only 0.25 inches below normal. Of this total, 1.41 inches fell during a single heavy rain event on October 27th – the city’s wettest day since last May. Despite this soaker, the Big Apple remains in a moderate to severe drought according to the latest report (released on 10/27) from the US Drought Monitor.
October was a temperature roller coaster in NYC. Credit: The Weather Gamut.
Rainfall was near average in NYC for the first time in months. Credit: The Weather Gamut