Residents of Florida and other Gulf Coast states may wonder why they seem to so frequently get pummeled by tropical depressions, tropical storms and hurricanes yet West Coast communities never seem to have the same problems. It’s not just a fluke or matter of luck.

• Northern hemisphere hurricanes begin in tropical or subtropical areas and usually travel west-northwest¹
• Water temperatures on the United State’s East Coast are usually over 80 degrees while West Coast rarely exceed the low 70s

Hurricanes that form in Pacific subtropical and tropical waters tend to move west-northwest, which means they either unleash their energy on the ocean or hit China or Southeast Asia islands and land masses.

That’s not to say the whole Pacific is cool and placid – the northwest Pacific far outpaces every other ocean when it comes to hurricane storm generation. The nature of currents, the ocean and weather patterns deprive Pacific-ocean hurricanes of the fuel they would need to reach the United State’s West Coast.

Why Is West Coast Water Colder Than East Coast Water?

Are you familiar with the phenomenon of how water flows differently in the northern hemisphere and southern hemisphere? The Coriolis effect is complicated, and you’re not going to witness it on the small scale of a sink drain or toilet. The effect is primarily viewable in large bodies of water and in things like hurricanes and cyclones.

What is true is hurricanes rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. The ocean’s surface water currents are similarly shaped by the Coriolis effect, but in this case water in the northern hemisphere flows roughly clockwise while southern hemisphere currents flow roughly counterclockwise.

In the Northern Atlantic, cold water flows down from the Arctic past Europe and Africa’s west coast where it’s warmed up near the equator before heading west to the Caribbean and north past the United State’s east coast. That warm water then heads back east to start the path over again in the Arctic.

The same phenomenon happens on the United State’s west coast. Cool water flows south from the arctic past the United State’s west coast before heading south past Mexico and Central America, where it’s warmed up again before heading west.

The same clockwise current occurs on both the East Coast and West Coast, but on the West Coast the water is coming from the Arctic, while the East Coast water is coming up from the equatorial Atlantic.

Ocean waters are not a uniform temperature from the surface to the ocean floor, and the world’s currents are not simple circles going round and round, but from a simplistic standpoint the surface water off the U.S. East Coast is a lot warmer than the West Coast, which is the primary reasons hurricanes hit Florida and not California.²  

Are Hurricanes in Florida Getting Worse or Better?

There seems to be a common refrain from some people that hurricanes have increased in frequency and intensity in recent years. Whether those trends are facts or influenced by better, more frequent news reports and other personal biases is up for debate.  

It’s not possible to confirm or deny the validity of those beliefs with absolute certainty, but experts can theorize with varying degrees of confidence. The Geophysical Fluid Dynamics Laboratory, a division of the U.S. government’s National Oceanic and Atmospheric Administration, published a detailed analysis of current research on this exact topic in February 2020.³

They rated the likelihood of their conclusions on a scale of:

• Very likely (greater than 90 percent likelihood)
• Likely (greater than 66 percent likelihood)
• More Likely Than Not (greater than 50 percent likelihood) 

They surmised we will experience:

• A likely increase in hurricane rainfall rates by 10 to 15 percent
• A likely increase in hurricane intensity by one to 10 percent globally for every two-degree Celsius increase in global temperatures
• A likely increase in proportion of storms that reach Category 4 and 5 intensity but no change or even a slight decrease in global frequency of all hurricanes/cyclones

The study’s authors made some other important observations:

• It’s too early to tell for certain if human-caused global warming has already had an impact on Atlantic hurricane activity
• There could potentially be changes that are so slight they are imperceptible to modern scientific measuring tools

From a Floridian’s standpoint, hurricane seasons today and hurricane seasons 100 years ago are similar from a frequency and intensity standpoint. Some years we get lucky, others we don’t.

We shouldn’t overlook the impact of improvements in building quality, preparedness, government coordination and evacuation strategies. Hurricanes today are much more survivable than they were 100 years ago thanks to exceptional forecasting, early warnings, stronger structures and all-around better preparedness.

It takes people working together to make these storms more survivable, regardless of what the future brings in terms of frequency and intensity. That’s why it’s important for Floridians to heed warnings, practice their evacuation plans and have well-stocked hurricane preparedness kits ready to go during this hurricane season.