Contiguous US Posts Sixth Warmest Winter on Record

The meteorological winter of December 2019 – February 2020 was unusually mild across most of the contiguous United States.

According to NOAA, the mean temperature for the lower forty-eight states was 36°F. At 3.8°F above average, the season now ranks as the nation’s sixth warmest winter on record.

Regionally, the eastern part of the country was particularly warm. Twenty-four states posted a winter season among their top ten warmest ever recorded.

Credit: NOAA

Winter is Warming Across the US

Winter is the coldest part of the year. But for most of the United States, it is the fastest warming season.

Across the contiguous United States, winter temperatures have increased an average of nearly 3°F over the past fifty years, according to Climate Central. The northern part of the country has seen the largest seasonal increase led by Burlington, VT with 6.8°F of warming since 1970.

Warmer winters may feel like a positive thing for some people, but they do not come without consequences. Periods of consistently cold temperatures help limit pest populations such as mosquitos and other pesky bugs. They also play an important role in plant development, especially for fruit trees that need a period of dormancy. Moreover, warmer winters threaten the livelihood of communities that depend on winter tourism, particularly ski resorts.

Looking ahead, as greenhouse gas emissions continue to increase, so too will the temperature and its associated impacts throughout the year.

Credit: Climate Central

Contiguous US Posts Fifth Warmest January on Record

January, the so-called Dead of Winter, was unusually mild across much of the United States. No state in the Lower 48 ranked average or below average for the month, according to NOAA.

Taken as a whole, the mean temperature for the contiguous states was 35.5°F.  At 5.4°F above the 20th-century average, January 2020 now ranks as the country’s fifth warmest January on record.

Regionally, the Northeast and Great Lakes were of particular note. Temperatures were much above average in both areas, with the Northeast posting its tenth warmest January and a large portion of the Great Lakes remaining unfrozen.

Credit: NOAA

2019: Second Wettest Year on Record for US

The defining weather story of 2019 in the contiguous United States was rain. The year was the second-wettest ever recorded in the lower 48 states. Only 1973 was wetter.

The annual precipitation total, according to a report by NOAA’s National Centers of Environmental Information, was 34.78 inches. That is 4.84 inches above the long-term average.

While above-normal precipitation was observed across much of the nation, some places were particularly wet. North Dakota, South Dakota, Minnesota, Wisconsin, and Michigan each posted their wettest year on record. Another 18 states finished in the top ten.

Months-long flooding in the upper Midwest and Mississippi River basin caused a tremendous amount of damage to farms and homes across the region. In fact, the combined cost of the Missouri, Arkansas, and Mississippi River floods was $20 billion. That adds up to about half the total cost of the 14 different billion-dollar weather and climate disasters that occurred in the US during 2019.

Heavy rain events and flooding are nothing new, but experts say climate change is making them worse. As greenhouse gases warm the atmosphere, the air is able to hold more water vapor. With evaporation from oceans, rivers, and lakes increasing, there is more water vapor available to condense and fall as rain.

Weather records for the contiguous United States date back to 1895.

Credit: NOAA

Autumn is Heating Up Across the US

Autumn is a transitional season. It is generally a time when the heat of summer fades away and the chill of winter gradually returns. But, as our climate changes, the season is heating up.

Across the contiguous United States, autumn temperatures have increased an average of 2.5°F over the past fifty years, according to Climate Central. The western part of the country has seen the fastest seasonal increase, with Reno, NV warming 7.7°F.  Las Vegas, NV, and El Paso, TX have each seen a rise of more than 5°F since 1970.

These warmer temperatures may feel like a summer bonus for some, but they also bring a number of negative impacts. Less frost-free days means the allergy season is extended and disease-carrying pests like mosquitos and ticks are able to live and thrive longer. Warmer temperatures also drive up energy bills, as people with air conditioning units use them longer into the season. This in turn, if they are powered by fossil fuels, adds even more heat-trapping greenhouse gases to the atmosphere.

Wildlife is also feeling the effects of a warming fall. The timing of when fruits ripen, for example, is being skewed from its “normal schedule”. In turn, this is impacting the once well-synced patterns of animal behaviors such as bird migration and hibernation.

Looking ahead, as greenhouse gas emissions continue to increase, so too will the temperature and its associated impacts.

Credit: Climate Central

Summer Nights are Getting Warmer Across the US

Summer is the time of year when warm temperatures are expected. As our climate changes, however, the season is getting even hotter, especially at night.

Since 2010, according to NOAA, there have been 34% more record-warm low temperatures set than record-warm high temperatures. Nationally, summertime lows have increased an average of 1.8°F since 1895, according to an analysis by Climate Central, a nonprofit science news organization. The southwestern part of the country has seen the greatest warming, with Reno and Las Vegas, Nevada showing an increase of 16.9°F and 9.1°F respectively. Not far behind are El Paso, Texas at 7.7°F and Salt Lake City, Utah at 6.6°F.

In addition to climate change, land use issues also play a role in our warming nights. Paved surfaces hold more heat than vegetated ones, so cities tend to be hotter than rural areas, particularly during the overnight hours. This is known as the urban heat island effect.

When temperatures do not significantly cool off at night, people do not get a chance to recover from the heat of the day. This can cause serious health concerns, especially for young children, the sick, and the elderly. Warmer nights also drive up energy bills, as people with air conditioning units use them more. This in turn, if they are powered by fossil fuels, adds even more greenhouse gases to the atmosphere.

Credit: Climate Central

Hurricane Barry Makes Landfall in Louisiana, Soaking Gulf Coast

Hurricane Barry made landfall at Intracoastal City, Louisiana on Saturday. It was the second named storm and first hurricane of the 2019 Atlantic season.

Coming ashore with winds measured up to 75 mph, Barry was classified as a category one hurricane. But, it was rain rather than the wind that had the biggest impact on the area. Moving slowly at about 7mph, the storm dumped heavy precipitation across the region, causing widespread flooding.  Some parishes even saw the water overtop levees in spots. The highest rainfall total of 23.58 inches was reported near Ragley, LA.  

Extensive power outages were also reported across Louisiana. According to state energy officials, more than 120,000 customers were in the dark in the wake of the storm.

While downgraded to a tropical storm after landfall, Barry is still laden with moisture. It is expected to bring heavy rain and flooding to regions further inland as it travels north into Arkansas.

Hurricane Barry. Credit: NOAA

Weather History: Thomas Jefferson and the Temperature on July 4, 1776

As the main author of the Declaration of Independence and the third President of the United States, Thomas Jefferson is regarded as one of this country’s Founding Fathers. He was also an astute and systematic weather observer.

Portrait of Thomas Jefferson by Rembrandt Peale, 1805. Credit: NYHS

In the summer of 1776, Jefferson was in Philadelphia, PA attending the Second Continental Congress, which adopted the Declaration of Independence.  While there, he purchased a thermometer and a barometer – new and expensive weather equipment at that time. On July 4, Jefferson noted that the weather conditions in Philadelphia were cloudy with a high temperature of 76°F.

For the next 50 years, he kept a meticulous weather journal.  He recorded daily temperature data wherever he was – at home in Virginia or while traveling.

In an effort to understand the bigger picture of climate in America, Jefferson established a small network of fellow observers around Virginia as well as contacts in a few other states. According to records at Monticello, his estate in Virginia, he hoped to establish a national network for weather observations. While this plan did not come to fruition during his lifetime, today’s National Weather Service considers him the “father of weather observers.”

Happy Independence Day!

An excerpt from Thomas Jefferson’s Weather Journal, July 1776. Credit: NCDC

Summers are Getting Hotter in the US

Summer is the warmest part of the year with high sun angles and long daylight hours. But, as our climate changes, the season is getting even hotter.

Across the contiguous United States, summer temperatures have increased an average of more than 2°F over the past fifty years, according to Climate Central, a non-profit science news organization. The western and southwestern parts of the country have seen the fastest seasonal increase, with places like Boise, ID, Las Vegas, NV, and McAllen, TX each warming more than 5°F since 1970.

Soaring temperatures can pose a risk to human health and cause energy costs to skyrocket as people try to beat the heat.  They can also lead to drought and threaten agricultural production.

Reducing global greenhouse gas emissions, which are causing the atmosphere to warm, can minimize many of these impacts. On a local level, adaptation measures are also important. In urban areas, which tend to heat up quickly, planting more trees can help keep neighborhoods cooler during the increasingly intense heat of the summer months.

Credit: Climate Central

May 2019: Second Wettest Month on Record for US

When it rains, it pours! This old adage was proven to be true last month. With national weather data dating back to 1895, May 2019 was the second wettest month ever recorded in the contiguous United States. Only May 2015 was wetter.

According to NOAA, an average of 4.41 inches of rain fell across the lower 48 states, which is 1.50 inches above average. Heavy precipitation was reported from the West Coast through the Mid-West, and into parts of the Northeast. Kansas, Nebraska, and Missouri each experienced their wettest May on record.

This relentless rain caused deadly and destructive flooding in several states along the Arkansas, Missouri, and Mississippi Rivers.

While there were a number of factors that contributed to May’s excessive rainfall, including El Nino, climate change also likely played a part.  As the National Climate Assessment points out, heavy precipitation events are increasing in both frequency and intensity across the United States as the atmosphere warms.

As greenhouse gases heat the atmosphere, the air is able to hold more water vapor. More specifically, according to the Clausius–Clapeyron relation, for every increase of 1°F, the saturation level of the atmosphere increases by about 4%. In other words, warmer temperatures lead to more evaporation from oceans, rivers, and lakes, and therefore more water vapor is available to condense and fall as precipitation.

Sadly, with our global temperature continuing to rise, experts say we should expect to see more extreme rain and flooding events in the future.

Credit: NOAA