Hurricane season in Florida: What's the difference between tropical storm, tropical depression, and hurricane?

Whether you've lived in Florida your whole life or are brand new to the state, it's important to know the difference between the various terms you'll likely hear during the traditional Atlantic hurricane season, which runs June 1 - Nov. 30, 2022.

Before hurricane season begins, it's important to prepare early and be as prepared as possible.

In very basic terms, hurricanes begin as cyclones – or atmospheric rotation way out in the ocean – and as the system intensifies (if it does) – more power, increased wind speeds -- it becomes a tropical wave, then a tropical depression, followed by a tropical storm, and eventually, a hurricane. When these systems become storms, that's usually where we see the National Hurricane Center name them (ie: Tropical Storm Ivan).

WHAT IS A TROPICAL WAVE?

According to National Hurricane Center, a tropical wave is a "trough or cyclonic curvature in the trade-wind easterlies."

WHAT IS A TROPICAL DEPRESSION?

When a cyclone's wind speeds reach 38 mph or less, it becomes a tropical depression.

WHAT IS A TROPICAL STORM?

To be classified as a tropical storm, surface winds have to be between 39 mph and 73 mph, which is one mph faster than a tropical storm.

WHAT IS A HURRICANE?

Once a tropical storm's wind speeds reach at least 74 mph, it is classified as a hurricane. From there, hurricanes are defined further using the Saffir-Simpson Hurricane Wind Scale, which is a five-point scale: Category 1, Category 2, Category 3, Category 4, and Category 5.

As a storm's wind speed increases, the category – and level of severity – increases.

Category 1: 74 mph - 95 mph sustained wind speeds
Category 2: 96 mph - 110 mph sustained wind speeds
Category 3: 111 mph - 129 mph sustained wind speeds
Category 4: 130 mph - 156 mph sustained wind speeds
Category 5: Wind speed greater than 156 mph

UNDERSTANDING A WATCH VS. WARNING

Whether it's a severe thunderstorm, tornado, storm surge, or hurricane, you've likely received an emergency alert on your phone regarding a weather watch, or warning. Here is the difference between the two:

  • A "watch" means conditions are possible. For example, a tropical storm watch means it's possible that a storm's wind speeds could reach 39 mph - 73 mph within next 48 hours.
  • A "warning" is a more significant advanced alert and means conditions are more than possible, but "expected." For example, a tropical storm warning means conditions (wind speeds of at least 39 mph to 73 mph) are expected within next 36 hours.