NYC Monthly Summary: August 2017

August was unusually mild in New York City this year. Of the month’s thirty-one days, nineteen posted below average readings, including an unseasonably cool 68°F on August 29. Furthermore, the month typically produces four days with readings in the 90s, but this year we only had one. In the end, the city’s mean temperature for the month was 74°F, which is 1.2°F below average.

In terms of precipitation, August was mostly dry. Overall, 3.34 inches was recorded in Central Park, marking the fourth month this year and second in a row to deliver below average rainfall. The city usually gets 4.44 inches of rain for the month.

August 2017 was unusually mild in NYC. Credit: The Weather Gamut

Solar Eclipse Cools NYC by Nearly 4°F

Monday marked the first time in decades that a total solar eclipse was visible in the continental US. The path of totality was about 70 miles wide and passed through 14 states, from Oregon to South Carolina. The rest of the country, however, saw varying degrees of a partial eclipse.

Partial Solar Eclipse 2017 seen from NYC. Credit: Melissa Fleming

Here in New York City, the magnitude was only about 72%. Nonetheless, this celestial event had a noticeable impact on the local temperature. Our weather station in mid-town Manhattan showed a drop of 3.7°F as the moon briefly obscured the afternoon sun.

The next solar eclipse that will be visible from the east coast will take place on April 8, 2024. So, hold on to those eclipse viewing glasses!

The solar eclipse peaked at 2:44 PM EDT in NYC. Credit: The Weather Gamut

Arctic Air Brings Brutally Cold Temperatures to NYC

A massive arctic outbreak has sent most of the U.S. into a deep freeze.  From the Mid-West to the Eastern Seaboard and down to the Gulf Coast, many cities are dealing with the coldest temperatures they have seen this season.

Here in New York City, the mercury fell to 8°F in Central Park this morning. Factoring in the wind chill, it felt like -8°F. Our normal low temperature for this time of year is 27°F.

As cold as it was today, it was not the coldest day the Big Apple has ever experienced. That dubious honor, according to the NWS, belongs to February 9, 1934, when the low temperature was a brutal -15°F.

Produced by a deep dip in the jet stream, our current frigid conditions are expected to stick around through the weekend. Bundle up!

Why Air Temperature Decreases with Height

While visiting Colorado recently, I had the opportunity to explore Rocky Mountain National Park, and it was largely a vertical experience. Within its borders are 72 named peaks that reach above 12,000 feet in elevation. Traveling from the Beaver Meadow Visitor Center – elevation 7,840 feet – to the Alpine Visitor Center – elevation 11,796 feet – the drop in temperature was anything but subtle.

The reason for air being cooler at higher elevations is twofold. First, the sun’s rays heat the Earth’s surface, which in turn, radiates that warmth into the atmosphere. As you climb in altitude, there is less surface area of land available to heat the air. Second, as air rises, it expands and cools. This is because air density and pressure aloft are lower than at the surface.

The exact rate at which the temperature decreases with height – the environmental lapse rate – varies with location and daily conditions. On average, however, for every 1000 feet gained in elevation, the temperature drops by about 3.6°F.

Image Credit:British Geographer

Image Credit: The British Geographer

Volatile March Temperatures in NYC

Up and down and back again, this was a volatile week for temperatures in New York City. Overall, it felt like we were on a weather roller-coaster.

On Tuesday, the high temperature in Central Park was a balmy 66°F – the city’s warmest day of the year so far.  Two days later, we were reminded that it is still winter when the mercury only made it to 32°F.  Today, the temperature rebounded to 58°F, but it is forecast to tumble into the mid-30s again tomorrow. Our normal high for this time of year is 49°F.

As jarring as they may be, these large temperature swings are par for the course in March. Transitioning from winter to spring, warm air in the south is expanding quickly while cold air lingers in the north.  As a result, temperature gradients can be very tight and local conditions can change abruptly.

Graph Credit: The Weather Gamut

Graph Credit: The Weather Gamut

An Early Spring Preview

This weekend, much of the eastern United States is enjoying a welcome relief from what has been a long and brutal winter. Temperatures are soaring well above average across the region making it feel like spring.

In New York City, the high temperature in Central Park reached 54°F yesterday and it is expected to climb into the mid 50s again today.  Last Sunday, the mercury only made it to 30°F.  Our normal high for this time of year is 43°F.

With feet of snow on the ground, these mild conditions have caused rapid melting throughout the area.  Although this has caused ice to fall from tall buildings and some localized flooding, many winter-weary New Yorkers are enjoying this early spring preview.

This warmer weather can be easy to acclimate to, but it is still February and winter is not letting go just yet. Cold conditions, including another arctic outbreak, are expected to return over the next few days.

The first patches of green lawn appear on Central Park's Green Meadow as temperatures soar and snow melts.  Image Credit: The Weather Gamut.

The first patches of green lawn seen in weeks on the Sheep’s Meadow of Central Park are revealed as temperatures warm and snow melts.    Image Credit: The Weather Gamut.

Australian Heat Wave 2014

Oppressive heat has been gripping southeastern Australia for days.  While it is summer there and high temperatures are expected, this heat has been extreme.

In the state of Victoria, temperatures soared above 40°C – that is 104°F – for four consecutive days.  In the neighboring state of South Australia, the mercury hit 44.2°C (112°F) in Adelaide – making it the hottest city in the world on Thursday. Officials say this intense heat has fueled wildfires, sent hundreds of people to the hospital with heat related illnesses, and caused widespread power outages.  In Melbourne, it even caused play to be suspended at the Australian Open – a Grand Slam tennis tournament.

Scorching heat waves seem to be getting more common in Australia.  Last year, the country’s hottest on record, the Bureau of Meteorology had to add two new colors to their weather map to reflect the higher temperatures.

This current heat wave is forecast to break over the weekend and a dramatic cool down is expected to follow.

Source: Australian Bureau of Meteorology

Source: Australian Bureau of Meteorology

Weather Whiplash for NYC

New York City was on a temperature roller coaster this week.  From unseasonably warm to brutally cold, we saw it all.

On Monday, it was 55°F in Central Park.  Then, in a matter of twenty-four hours, from 8 A.M. on Monday to 8 A.M. on Tuesday, the temperature in the city dropped 51°F!  With a low reading of 4°F on Tuesday morning, the Big Apple set a new record low for the date.  This dramatic change was ushered in by a weakened polar vortex and a deep dip in the jet stream.  After a few days of bitterly cold conditions, the mercury climbed above freezing on Friday and then continued to rise. On Saturday, the city’s temperature reached a relative balmy 58°F!  Our average high for this time of year is 38°F.

From the mid-50s to the single digits and back again in a matter of six days, it felt like weather whiplash!  Temperature swings of this magnitude in NYC are very unusual.

Image Credit: The Weather Gamut

Graph Credit: The Weather Gamut

The Dead of Winter

The deep freeze that gripped much of the U.S. this week has begun to thaw.  The “Dead of Winter”, however, is just beginning.

While actual daily weather varies, this old saying refers to what is statistically the coldest part of the winter season.  Between January 10th and February 10th, average temperatures reach their lowest point of the year in the northern hemisphere.

These few weeks are the climatological opposite of the “Dog Days of Summer“.

A Deep Freeze in NYC

A massive arctic outbreak has sent most of the U.S. into a deep freeze.  From the Mid-West to the Gulf Coast and along the eastern seaboard, many cities are dealing with the coldest temperatures they have seen in nearly two decades.

Here in New York City, the mercury fell to 4°F in Central Park this morning – a new record low for the date.  The previous record of 6°F was set in 1896. Our normal low temperature for this time of year is 27°F.

While it certainly was bitterly cold today, it was not the coldest day the Big Apple has ever experienced. That dubious honor, according to the NWS, belongs to February 9, 1934, when the low was a brutal -15°F.

Our current frigid conditions are the product of a weakened polar vortex – the pattern of winds around the North Pole.  As it slowed down, arctic air pushed southward and caused a deep dip in the jet stream. This frosty air is not likely to stick around much longer, though.  As the jet stream retreats northward, temperatures are forecast to rebound to more seasonable, and even above average, levels by the end of week.

Image Credit: Mesonet

Image Credit: Mesonet