Here’s why the early arrival of extreme heat in Houston is dangerous

Temperatures in Houston heading into Memorial Day weekend are already reaching the 90s, with the humidity making the air temperature feel more like 100 degrees, but if you’re not used to that heat, it could be dangerous.

Although this week’s heat was near record highs, it’s not entirely foreign to Southeast Texas: It’s just unusual for it to arrive this early. National Weather Service forecasters have warned of the need to acclimate to the early season heat, as humidity and unrelenting sun can take a greater toll on a body that still thinks it’s spring.

EXTREME HEAT: Here’s when Houston typically hits 100 degrees and how other Texas cities compare

“The first average day of temperatures above 95 for the city of Houston is June 13, so this is an early season heat period and our bodies are not yet acclimated to it,” wrote the weather service Cameron Batiste in a forecast statement Wednesday. “This is happening on a holiday weekend and we know you may have plans outside, so be sure to follow thermal safety rules to protect yourself and your loved ones.”

The weather service recommends:

• Drink plenty of water to stay hydrated. Water is best because alcohol and some carbonated drinks can actually dehydrate you.
• Take frequent breaks to protect yourself from the sun and avoid strenuous outdoor activities during the hottest parts of the day.
• Wear loose or light clothing
• Always look before locking your vehicle. Never leave a child or pet inside a vehicle, where temperatures can reach deadly levels within minutes on a hot day.
• If you are a pet owner, be careful on the sidewalk when it is hot. If the ground is too hot for the palm of your hand, then it is too hot for
  their paws.

ALERTS EXPLAINED: Houston is bracing for intense heat this week. What is a heat advisory? What do heat alerts mean?

Another factor that adds to the heat is the humidity level of the air, which can be indicated by dew points, or the temperatures at which dew forms or when relative humidity reaches 100%. As a general rule, the more moisture the air is saturated with, the higher the dew point. Houston can therefore expect oppressive humidity and sticky air if the dew point is at least 65 degrees. This week, dew points range from 73 to 77 degrees.

To make matters worse, Houston’s humidity, or the level of water vapor in the air, can make our perception of heat seem much hotter than the actual temperature. This is because the body cools itself through the evaporation of sweat from our skin. But such evaporation is not as effective when there is already too much moisture in the air.

The heat index takes this into account, which is why on Wednesday the actual air temperature may be 91 degrees, but a high humidity level (for example, a dew point of 74 degrees) may cause the It feels like it’s more like 101.

Thermal safety involves implementing measures to prevent heat-related illnesses and injuries. This involves staying hydrated, wearing light, breathable clothing, and avoiding strenuous activities during the hottest parts of the day. Using shade and air conditioning can help regulate body temperature.

Thermal safety also involves understanding the signs of heat exhaustion and heat stroke, such as heavy sweating, dizziness and nausea, and knowing how to respond quickly to these symptoms.

Heat cramps, the first sign of heat stress, involve painful muscle cramps and spasms, usually in the abdomen and legs, accompanied by profuse sweating. Applying firm pressure to the muscles and drinking water may help, but avoid giving water if nausea occurs. See a doctor if cramps last more than an hour.

FOLLOW WARM WEATHER: As temperatures warm, use our interactive maps to see how much above normal temperatures will be where you live.

Heat exhaustion involves heavy sweating, weakness, cold, clammy skin, and a rapid, weak pulse. Symptoms may also include dizziness, nausea, vomiting, headache, fainting, or muscle cramps. To lower body temperature, move the person to an air-conditioned room, apply cool, damp cloths, or have the person sit in a cool bath. See a doctor immediately if symptoms persist for more than an hour.

Heat stroke is the most serious heat-related illness, characterized by a body temperature of at least 103 degrees. Symptoms include throbbing headaches, dizziness, nausea, vomiting, red, dry skin, and a fast but weak pulse. Fainting or loss of consciousness may occur without immediate treatment. Call 911 and move the person to an air-conditioned area using cool, damp cloths. Do not give fluids, as this may cause pulmonary edema or fluid in the lungs. Delaying medical care can be fatal.