There is an old saying that if you don’t like Missouri weather, just wait a few minutes. While that certainly applies to our rapidly changing weather patterns, there is one thing that remains remarkably consistent every summer: the heat. Not just the temperature itself, but the thick, heavy humidity that seems to settle over the state like a blanket. It is the kind of air you can almost see and certainly feel. Step outside for only a few moments, and your glasses fog, your shirt clings to your back, and you begin to understand why Missourians have a love-hate relationship with summer.
Every year, as temperatures climb into the 90s and heat index values soar well above 100 degrees, many people hear terms like Heat Advisory, Extreme Heat Watch, or Extreme Heat Warning and wonder what they mean. While they may sound like different ways of saying the same thing, each one represents a different level of concern from the National Weather Service. Understanding the difference is more than simply knowing weather terminology. It can help you make decisions that protect your health and, in some cases, save lives.
A Heat Advisory is often the first indication that the weather is becoming dangerous. It means a combination of high temperatures and humidity is expected to create conditions where heat-related illnesses become much more likely, particularly for those who spend extended time outdoors. While many people hear the word “advisory” and assume it is simply a recommendation, it should not be taken lightly. Missouri’s humidity makes it far more difficult for the body to cool itself through perspiration. As sweat loses its ability to evaporate efficiently, body temperature begins to rise, increasing the risk of heat exhaustion and, if ignored, heat stroke. Older adults, infants and young children, individuals with chronic medical conditions, outdoor workers, athletes, and anyone without access to air conditioning are especially vulnerable during these periods.
An Extreme Heat Watch raises the level of concern. Unlike an advisory, a watch is issued when forecasters believe conditions are becoming favorable for an exceptionally dangerous heat event over the next day or two. Think of it as an opportunity to prepare before the worst conditions arrive. It is a reminder to ensure your air conditioning is functioning properly, stock up on water, rearrange outdoor plans if possible, and check on family members or neighbors who may be especially susceptible to the heat. Watches provide valuable lead time, allowing communities and individuals to prepare before the most dangerous conditions develop rather than reacting after they are already underway.
The highest level of alert is an Extreme Heat Warning. This means dangerously high temperatures and oppressive humidity are either occurring or expected very soon, creating conditions where heat-related illnesses can develop quickly. During these events, prolonged exposure to the heat can become life-threatening. Heat stroke, unlike heat exhaustion, is a true medical emergency. Symptoms such as confusion, altered mental status, loss of consciousness, a rapid pulse, or a body temperature exceeding 104 degrees require immediate medical attention. Every summer across the United States, excessive heat claims more lives than tornadoes, hurricanes, floods, or lightning. While severe storms often receive greater attention because of their dramatic images, heat remains one of the nation’s deadliest weather hazards because its effects are often gradual and underestimated.
One of the biggest misconceptions I hear is that Missouri is not as hot as places like Arizona or Nevada. While our actual air temperatures may be lower, our humidity often makes Missouri feel significantly hotter. Meteorologists use something called the heat index, which combines air temperature with relative humidity to estimate what the temperature actually feels like to the human body. A 95-degree afternoon in Missouri can easily feel like 110 degrees or higher because the moisture in the air limits the body’s ability to cool itself. That is why people often describe the air as “heavy.” It is not just uncomfortable. It is physically taxing on the body.
The dangers of extreme heat extend well beyond people. Every summer, veterinarians treat countless pets suffering from heat-related illnesses. Dogs, unlike humans, rely primarily on panting to regulate their body temperature, making them particularly susceptible during periods of prolonged heat. Pet owners should always provide fresh water, shade, and avoid walking dogs on pavement that has become dangerously hot under direct sunlight. If the pavement is too hot for the back of your hand, it is too hot for your dog’s paws. And, of course, it bears repeating every year: never leave a child or pet unattended inside a parked vehicle. Even with windows cracked, temperatures inside a vehicle can climb to deadly levels within minutes.
One of the qualities I have always appreciated about living in Missouri is the willingness of neighbors to look after one another. During periods of dangerous heat, that sense of community becomes especially important. A simple phone call to an elderly parent, a visit to a neighbor who lives alone, or offering someone a ride to a cooling center can make a tremendous difference. Many heat-related fatalities occur quietly behind closed doors among individuals who simply did not have the resources or ability to escape the heat.
As a meteorologist, I often spend much of the spring focused on severe thunderstorms, tornadoes, and flooding. Those events deserve our attention, but when summer settles over Missouri, excessive heat often becomes the greatest weather threat we face. It lacks the dramatic radar images or swirling clouds that dominate television coverage, yet year after year it quietly becomes one of the deadliest forms of weather in the country.
So, the next time you hear a Heat Advisory, recognize that dangerous conditions are developing and take precautions. If an Extreme Heat Watch is issued, use that time to prepare yourself and your family. And when an Extreme Heat Warning is posted, understand that the threat is immediate and serious. The difference between discomfort and danger can sometimes be only a few degrees, especially when Missouri’s relentless humidity is part of the equation.
After all, this is Missouri. We expect thunderstorms, we prepare for tornado season, and every summer we learn once again that heat deserves every bit as much respect. Welcome to another Missouri summer. Stay hydrated, look after one another, and remember that sometimes the most dangerous weather is the weather you cannot see.
