What is a heat wave?

A heat wave is an extremely dangerous weather condition where temperatures soar well above 90° F. This high heat combines with high levels of humidity and creates a heat bubble over a certain area for an extended period of time.

What causes a heat wave?

Heat waves are caused by a strong high pressure settling in at 10,000-25,000 ft. and not moving. This causes warm air to sink. The result is a dome of hot air that traps the heat near the ground and prevents cooling convection currents from forming clouds.

How hot can a heat wave get?

The temperature of a heat wave is well over 90° F with high humidity, making it feel a great deal hotter. Weather forecasters use a heat index to determine how much hotter the effect of the humidity is making the day feel. For example, if it is 84.5° F with humidity levels of 84%, the day feels more like 98° F. 

Where do heat waves occur?

Heat waves are not just confined to the areas we usually think of as hot. Heat waves can occur anywhere high-pressure air settles. This still creates an environment that can form a heat dome. 

What is a heat advisory?

A heat advisory is a warning issued when the maximum heat index temperatures could exceed 100° F or higher for at least two days without the evening air dropping below 75° F.

Is a heat wave a natural disaster?

While heat waves may not have the excessive winds or rain that you think of when considering natural disasters, they are in fact a natural disaster. 

How do heat waves affect the environment?

Heat waves affect the environment through both high temperatures and low rainfall. These two factors combine to make conditions ideal for droughts and wildfires. The droughts and wildfires caused by heat waves can have huge influences on the surrounding vegetation and wildlife. Plants that need higher levels of water or more shade can die as a result of heat waves. Wildlife struggling to keep cool or find adequate water can also perish, which in turn, can affect the environment and their respective ecosystems.

What are the dangers of a heat wave?

Heat waves can be one of the most threatening weather phenomena. This is due to the fact that heat waves not only have high temperatures but also high levels of humidity. Humidity hinders the body's ability to sweat;  the higher the humidity the hotter the day feels.

Some of the main dangers associated with heat waves are dehydration, heat exhaustion, heatstroke and even death. The effects of heat waves are extremely dangerous for infants and the elderly because both can have difficulty maintaining body temperature. Additionally, those unable to take shelter in a cooled building can be extremely impacted by the dangers of heat waves.

What do I do during a heat wave if I don’t have air conditioning?

During a heat wave it’s important that you try and keep yourself cool. Without AC this can be tricky, but not impossible. When possible, leave your home to seek out places that do have AC. But in order to keep your home as cool as possible open your windows at night to let in cool air. In the morning, close windows to try and shut out the day's heat for as long as possible. Only open them when it gets too stuffy. You should place fans strategically in your home to create cross breezes.

How do heat waves affect animals?

Animals, just like humans, are affected by the high temperatures and high levels of humidity. But unlike humans, they may not have access to an air-conditioned building. You may see fewer animals out around you – as they will probably seek out shaded areas to try and escape the heat.

How do heat waves affect the economy?

Potentially higher prices – Even short droughts caused by the excessive heat in a heatwave can decrease plant production and result in higher prices in the market.

More energy usage – Keeping cool during a heatwave increases energy consumption due to running air conditioners. 

Can heat waves impact the power grid?

When temperatures rise, increased air conditioning use means more electricity demand, which can put extra stress on the electric grid. High temperatures can also have a physical impact on transmission lines. Working together to conserve electricity, especailly during a heatwave, means a better chance for us to stay cool and comfortable.

Sources

"The Economic Realities of Heat Waves" Forbes