Record High Temps vs. Record Low Temps

In a stable climate, the ratio of new record highs to new record lows is approximately even. However in our warming climate, record highs have begun to outpace record lows, with the imbalance growing for the past three decades. This trend is one of the clearest signals of climate change that we experience directly.

Hurricane Florence September 2018

Hurricane Florence made landfall near Wrightsville, North Carolina Friday morning, September 14, as a Category 1 hurricane. Widespread rainfall totals of 20 to 25 inches, with isolated storm totals of greater than 30 inches, were recorded.[1] Elizabethtown received 35.93 inches between 2:00p EDT in September 13 and 10:00a EDT September 17.

Rainfall increased by over 50 percent in the heaviest precipitating parts of Florence due to human interference in the climate system, according to a first of its kind advanced forecast attribution statement about the influence of climate change on a tropical cyclone.[2] Additionally, a rapid analysis found that sea level rise was responsible for 11,000 (20%) of the homes impacted by Florence's storm surge.[3]

Climate change affects hurricane activity and amplifies the damages in several ways including: (1) increasing the rainfall that drops during the storm, (2) increasing sea surface temperatures which in turn raises the maximum potential energy that a storm can reach, and (3) elevating storm surge, via sea level rise, which greatly extends the storm's reach along low-lying areas.

Sea surface temperatures along Florence's path were 3.6°F (2°C) hotter than normal.[4] The storm progressed slowly for several days near the US coastline bringing extreme precipitation totals to the Southeast.[5] A similar situation contributed to the record rainfall during Hurricane Harvey in August 2017.

Eastern US Arctic Invasion and Winter Storm January 2018

The intense cold hitting the United States during the first week of 2018 continued with a heavy snowstorm that inundated the Northeast seaboard beginning the night of January 3 through January 4. The combined impact of the arctic outbreak and the intensified nor’easter landed a double whammy in which new record low temperature records were set.

Science studies and models report that the outbreak of arctic air bringing freezing temperatures to the lower United States is consistent with the climate disruption expected on a warming planet where the Arctic heats up faster and cold air is displaced to the south.

Unusually warm offshore waters also amplified the temperature contrast between land and ocean surfaces. This temperature contrast is what generally fuels nor’easters. These conditions over the Atlantic are consistent with the long-term climate change trends that intensify nor’easters.

While climate change warms the planet as whole, it also disrupts regional weather patterns, sometimes displacing cold air to the south. The overall warming trend continues but cold conditions can move. The record setting heat events recently observed further north in parallel to cold conditions in the continental US are consistent with this pattern of disruption.

Thomas Fire 2017

Higher temperatures, drier conditions, increased fuel availability, and growing warm seasons—all linked to climate change—are increasing wildfire risk in California.

In 2017, the combination of a wet winter followed by extreme heat and dry conditions has fueled record wildfires in many Western states.[1]

In early December, a series of fires extended this trend when they erupted in the mountains north of Ventura and Los Angeles, California.

The Thomas Fire, which began on the evening of December 4, is the largest blaze and grew quickly to nearly 31,000 acres (50 square miles) in less than 12 hours.[2] As of January 1, 2018, the Thomas Fire was 92 percent contained and had burned 281,893 acres establishing it as largest fire in California recorded history.[3][4] A mixture of dry foliage, low humidity and high sustained winds of more than 30 miles per hour led to its explosive growth, according to Fire Sgt. Eric Buschow.[5] Other major fires included the Creek and Rye events.

Research indicates a direct causal link between human-induced climate change and increased wildfire risk in California.[6] Climate change has contributed to California's longer fire seasons, the growing number and destructiveness of fires and the increasing area of land consumed.[7][8] 

California Wine Country Fires October 2017

Trends in California driven by climate change—including higher temperatures and drier conditions—are elevating the risk of dangerous and destructive wildfires across California and the western United States.

On October 8, a group of fires exploded across a wide swath of Northern California.[1] Taken as a group, the fires are among the worst on record in the state in terms of lives and property lost.[2][3] After just one week, the fires have killed at least 41 people, burnt more than 200,000 acres, destroyed or damaged more than 5,500 homes, and displaced 100,000 people.[4] Governor Jerry Brown declared a state of emergency in Butte, Lake, Mendocino, Napa, Nevada, Orange, Sonoma and Yuba counties.[5]

By the end, the Wine Country fires killed 42 people, destroyed 8,700 homes and buildings, and burned 245,000 acres.[6] The event was deadliest, most destructive, and one of the largest fires in California history.[7][8][9][10]

The combination of a wet winter followed by extreme heat and dryness has fueled record wildfires in many Western states.[11] Climate change compounds the risks of wildfires by extending the length of the fire season and adding to the intensity of droughts and heat waves. Park Williams, a climate and drought expert, noted, “... the combination of dry fuel, extreme heat and climate change is a recipe for what we are seeing."[12]

Hurricane Maria 2017

The record-breaking rainfall and flooding driven by Hurricane Maria—as well as Hurricanes Harvey and Irma just weeks before—is consistent with the long-term trend driven by climate change.

Hurricane Maria made landfall in Dominica as a Category 5 hurricane on September 18,[1] then hit southeast Puerto Rico on September 20 with 155 mph winds and a central pressure of 917 millibars.[2] It was the third strongest storm to make landfall in the United States.[3] "1,000-year" rains inundated much of eastern and northwestern Puerto Rico.[4] The storm knocked out power to the entire island of Puerto Rico, home to 3.5 million people, leading to a prolonged humanitarian crisis.[5]

Extreme rainfall is increasing worldwide due to climate change. In Puerto Rico, rain falling in very heavy events increased at least 33 percent from 1958-2012. Seas are now higher due to global warming, so storm surge drives much further inland. There has also been a global increase in the observed intensity of the strongest tropical cyclones, correlated with observed trends in sea surface temperatures in recent decades. 

La Tuna Fire September 2017

Higher temperatures and drier conditions—both linked to climate change—are increasing wildfire risk in California.

The La Tuna Fire erupted north of downtown Los Angeles and, at more than 7,000 acres, the fire is the largest to burn within Los Angeles' city limits.[2]

While small compared to the biggest fires in California's history,[1] the La Tuna Fire is notable for its proximity to a major city and its rapid growth amid unseasonably warm temperatures. The fire also erupted at the edge of the Angeles National Forest, a region where bark beetle activity has increased in recent years of extreme heat and drought.

California Statewide Heat Wave September 2017

"The greatest statewide heat wave ever recorded in California"[1] began in late August and lasted through early September, as a major high pressure system stalled over the western United States. Many locations broke daily, monthly, and all time temperature records.[2] Most notably, San Francisco broke its all time heat record, reaching 106°F on September 1.[3]

Record breaking heat waves are a classic signal of climate change. The trend in global warming has contributed to the severity and probability of 82 percent of record-hot days globally over the 1961-2010 period.[4]

The heat wave bears several signatures of heat waves on a warming planet: record-breaking heat, hot nights, high humidity, long duration, and increasing frequency.

This heat wave comes on the heels of June’s heat wave, which also broke temperatures records across the state.

Hurricane Irma 2017


Climate change is amplifying the damage done by hurricanes, by elevating sea levels and thus extending the reach of storm surge, and by loading storms with additional rainfall and thereby increasing flood risk. 

Climate change may also be driving the observed trend of increasing hurricane intensity[1] as well as the observed trend of more rapidly intensifying hurricanes.[2][3] 

In addition there is significant evidence linking climate change to the observed shift in the track of hurricanes such as Irma toward the US coast.[4]

Hurricane Irma maintained maximum wind speeds of at least 180 mph for 37 hours, longer than any storm on Earth on record, passing Super Typhoon Haiyan, the previous record holder (24 hours).[5] Irma’s maximum accumulated energy over 24 hours was the highest for any Atlantic hurricane on record.[9] The storm intensified into a Category 5 with 185 mph winds on September 5, making it the most powerful Atlantic hurricane ever recorded outside of the Caribbean and Gulf of Mexico where warmer waters make those areas more prone to stronger cyclones.[6]

Hurricanes are fueled by available heat. As global warming heats sea surfaces, the energy available to power hurricanes increases, raising the limit for potential hurricane wind speed.[7]

Irma intensified in the Atlantic from September 4 to 5 as it entered a region of sea surface temperatures ranging from 0.9°F to 2.25°F (0.5°C to 1.25°C) above average, relative to a 1961-1990 baseline.[8]