Every year, about 10,000 thunderstorms, 5,000 floods, and 1,300 tornadoes roll across the United States, and someone has to keep track of them all (plus, all of those record highs and lows). Meteorologists spend their careers analyzing complex data from multiple sources to come up with a daily forecasts and potential long-term outcomes for our planet. Here's how they accurately predict the weather. (Spoiler: It's harder than it looks on TV.)
Meteorology Before Modern Technology

Many ancient cultures had ways of monitoring the weather, often based on astronomical and seasonal observations. Toward the end of the Renaissance, inventors began to devise instruments — such as the hygrometer, which calculates humidity — to more accurately measure weather phenomena.
Robert FitzRoy, best known as Charles Darwin's captain on the HMS Beagle, coined the term "weather forecast" in the 19th century. At the time, predicting the weather was based on wind speeds and directions or the appearance of clouds. FitzRoy brought scientific rigor to the process and developed his own charts and tools to discern weather patterns. After a horrific storm sunk a passenger ship off Wales in 1859, FitzRoy began telegraphing storm warnings to British ports. In 1861, The Times in London began printing FitzRoy's weather forecasts two days in advance.
Collecting Weather Data Today

Meteorology has come a long way in the last 150 years. Now, sophisticated tools are constantly collecting weather data all around the globe. In the U.S., the National Weather Service, part of the National Oceanic and Atmospheric Administration (NOAA), is the main government agency that handles weather forecasting. NOAA's vast network of radar towers, satellites, airborne sensors, and surface-based observing systems monitors precipitation, temperature, wind speeds, air pressure, humidity, and other factors. The data is transmitted to NOAA's supercomputers, which make billions of calculations per minute. Those equations are fed into computer models, and meteorologists use the models to predict future weather. Companies like AccuWeather and The Weather Company also collect data, create their own models, and make forecasts.
What Meteorologists Actually Do

The American Meteorological Society (AMS) broadly defines a meteorologist as a person "who uses scientific principles to explain, understand, observe, or forecast the Earth's atmospheric phenomena and/or how the atmosphere affects the earth and life on the planet."
Even with supercomputers crunching most of the numbers, human meteorologists are still necessary. With their background in science, meteorologists compare information from different computer models and make their own predictions. (It's common to see a TV weathercaster compare models when predicting the path of a hurricane, for example.)
They also translate the mathematical models into real-world information. "The trick is … to approach the weather as if you're telling a story: Who are the main actors? Where is the conflict? What happens next?" Weather Underground meteorologist Bob Henson said in 2018. Meteorologists can tell you if your picnic is going to get rained out or if a sticky feeling in the air is going to make sleeping uncomfortable.
Training for a Meteorology Career

Meteorologists go through many years of specialized education and training. Beginning in high school, aspiring weather forecasters are encouraged to take algebra, trigonometry, and science courses, which prepare them to major in atmospheric science in college and take more classes in physics, math, chemistry, and related fields. The National Weather Service's minimum requirements for students pursuing such a degree call for hours of instruction in atmospheric dynamics, analysis and prediction of weather systems, remote sensing, physics, physical hydrology, climatology, statistics, and other technical sciences.
Some students may continue on to graduate school and specialize in a particular facet of meteorology. Those looking for careers as TV weathercasters can concentrate in broadcast meteorology at a some U.S. universities, including the University of Miami and Mississippi State University. Students also pursue internships at government agencies, news outlets, and forecasting companies to build their skill sets.
Surprisingly, there are no specific qualifications for meteorology — anyone who has some training and experience in atmospheric science can call themselves a meteorologist — but the AMS does offer certification programs for its members specializing in broadcast, consulting, and teaching.