Extreme Cold

Over the past 40 years, major freeze events and winter storms have caused 30 billion-dollar disasters totaling over $120 billion dollars. Despite overall warming trends globally, swings in extreme temperature shifts can result in more precipitation available for major winter weather events and can result in ‘heavier hitting’ events.

Following the warmest years on record, 2023 produced a record cold event: In 2023, Mount Washington in New Hampshire recorded a national wind chill record of 108 degrees below 0 at the start of February, while the actual temperatures were negative 47 degrees with a wind speed of 89 mph.

Areas which have historically seen few freeze events could experience more damaging winter storm events as the jet stream becomes unstable earlier in the year from widespread abnormal heating. This instability causes deeper, slow-moving low-pressure systems that cause larger associated winter storms.

Damages from these events were caused by icing, freezing rain, heavy snow, ice storms, freezing spray/fog, and lake effect snow events which can all be amplified by climate change through increased polar vortex intensity.

Extreme Cold is temperatures that are lower than historical averages to the point that it creates a dangerous environment for people, animals, and critical infrastructure. What constitutes as ‘extreme cold’ can vary across different areas of the country as some regions are less accustomed to winter weather and freezes.

Extreme cold events are often amplified or caused by:

• Polar Vortex – A large area of low pressure and cold air surrounding both of the earth’s poles. It’s a counterclockwise flow of air that helps keep the colder air near the poles.
• Cold Air Damming – The phenomenon in which a low-level cold air mass is trapped topographically. Often, this cold air is entrenched on the east side of mountainous terrain and often implies that the trapped cold air mass is influencing the dynamics of the overlying air mass.
• Blizzard – Sustained wind or frequent gusts to 35 miles an hour or greater and considerable falling and/or blowing snow (potentially reducing visibility to less than a quarter of a mile) for a period of three hours or longer.
• Lake-effect Snow – Forms when cold, below-freezing air passes over a lake’s warmer waters. This causes some lake water to evaporate and warm the air. The moist air moves away from the lake, cools, and falls to the ground as snow.

• Freezing Rain – Freezing rain is precipitation that reaches the ground in liquid form and then freezes on contact. The deposits of ice are called glaze. Glaze is not snow or sleet. The total icing accumulation is measured as a radius from stationary objects like twigs or fence wires.

• Ice Storm – Occasions when damaging accumulations of ice are expected during freezing rain situations. Significant accumulations of ice, more than one-half inch, pull down trees and utility lines resulting in loss of power and communication.
• Freezing Fog – Tiny, supercooled liquid water droplets in fog can freeze instantly on exposed surfaces when surface temperatures are at or below freezing.  

Extreme cold events typically follow a winter storm event, this causes a secondary threat to energy infrastructure, transportation, and any exposed infrastructure that experienced precipitation during the winter storm which can worsen freeze damages and delay restoration efforts.

CISA’s Role in Increasing Extreme Cold Resiliency

CISA provides winter outlooks combining the NOAA and academia forecasts for the season along with known risks to each critical infrastructure sector and highlights climate change heightened impacts to encourage resiliency planning.

CISA also produces weekly summaries highlighting major weather events of concern and the regional concerns for amplified risk in a timely manner for all stakeholders and partners.

Critical Infrastructure Impacts

Critical infrastructure impacts can range across multiple sectors. Potential infrastructure damage includes dislodged dams along rivers which can damage bridges and river infrastructure, degraded or halted transportation due to zero visibility, and damaged critical equipment from temperatures/frozen precipitation. As temperature extremes continue to fluctuate, pre-season freezes and shifts in warming could result in double blooms, premature budding, and early snowmelt which can increase scraggly brush growth and worsen wildfire threats each year.

Ice can increase the weight of tree branches up to 30 times and can add 500 pounds of extra weight causing stress failure. Ice and freezing temperature can also cause:

• Frozen electrical equipment such as transformers, renewables like windmills and solar panels, and fuel pipelines can result in an inability to meet energy demands. In addition, power plants in warmer places often have pipes and equipment exposed to the air, which means cold temperatures can cause more damage. In Texas in 2021, these factors led to 2/3 of the population losing power and significant water service disruption (The Washington Post, https://www.washingtonpost.com/climate-environment/interactive/2023/cold-infrastructure-transportation/).
• Damaged aircraft water systems, resulting in aircraft damage or other mechanical issues and can make runways hazardous for incoming aircraft.
• Road closures and significant car crash situations
• Cracked water, oil, and gas pipelines, frozen substances causing pressure buildup/expansion damage, and soil shifts at the base of supporting structures can result in damage or pressure loss.
• Structural collapse, such as roof failure, under the weight of frozen precipitation accumulation, causing damage, disruption to operations, and even loss of life.
• Damaged concrete and steel supports, foundations, and pipelines/railways as the expansion and contraction of the material can cause movement in the structures.