365 Days of Climate Awareness 169 – 2018 State of the Climate, North America

2018 US Climate Data

• Global atmospheric CO₂ concentration: 407.62 ppm, +2.4 ppm from 2017
• Average air temperature: 56.2°F, 4^th all-time 1895-2021
• Average precipitation: 34.65”, +4.71” over mean
• Tornadoes: 1126, 178 (10%) below the 1991-2010 average 1251
• 15 named tropical cyclones: 8 hurricanes, 2 major (winds > 111 mph, 3-5 Saffir-Simpson)
• Atlantic ACE: 144.86 x 10⁴ kts² (1991 - 2020 mean: 108.7 x 10⁴ kts²)
• ENSO: Weak La Niña early, neutral through summer, weak El Niño late

Larger Version

North American Conditions

• Warmer than average: Northwestern Canada; eastern, southern, western US; Mexico
• Cooler than average: Central and eastern Canada; upper northwestern US
• Drier than average: Western and southwestern US; Baja Peninsula, Mexico
• Wetter than average: Eastern, central and southern US; northern and central Mexico
• Wildfires: British Columbia, 1.3 million ha (3.2 million acres) burned; US 3.5 million ha (8.6 million acres) burned
• Snow cover: 24.9 x 10⁶ km² winter maximum vs 1966 - 2020 average 25.1 x 10⁶ km²

The Atlantic hurricane season, while not as active as 2017, was still well above-average, befitting the La Niña conditions. The two major hurricanes, Florence and Michael, made landfall in the United States and caused $49B in damages. Twelve cyclones—ten from the Pacific and two from the Caribbean—impacted Mexico, more than twice the average of five, making it Mexico’s most active cyclone season up to then.

British Columbia endured its worst wildfire season to date, with 1.3 million ha being consumed by more than 2000 separate wildfires, including a single-day high count of 460 on August 8. Though the annual average for precipitation in the region was close to the 1981-2010 average, a very wet winter was followed by an extremely dry spring (despite a somewhat rainy June). Several lightning strikes ignited the fires in July, which became so severe that British Columbia declared a state of emergency which lasted from August 15 until September 7.

2018 US Percentage Area Very Warm vs Very Cold (top 10th percentile of each)

Record-setting fires also scarred California, including the Ranch, Camp, Carr and Woolsey fires.  730,000 ha (1.8 million acres) burned between July and November. They resulted in nearly 100 deaths and $27B in damages. Human agency was the suspected cause of most, though conditions were extremely ripe for a disastrous fire. After five years’ drought throughout California, extensive rain in 2016-17 spurred the growth of grass, to the point that the dried-out dead grass from the previous years—called “fuel load”, meaning unconsumed dead plant material—was ready burning.

2018 US Percentage Area Very Wet vs Very Dry (top 10th percentile of each)

Tomorrow: 2018 state of the world climate.

Be brave, and be well.