1. Why is the minimum wind speed of a hurricane 74 mph and not 75 mph?

This is a good question. I don't recall anyone asking me this question before. The simple answer is that 74 mph is defined by the Saffir-Simpson Scale as the threshold for a Category 1 hurricane. Most people think that this is a quantitative measure of hurricane strength. But actually it is only a qualitative description of the relationship between hurricane winds and the resultant damage. For example, just think of speeding limits. On some highways, the speed limit is 75 mph. Why it is 75 mph but not 74 mph or 76 mph? Again, this is a qualitative measure. It only means that when your speed is up to this number it becomes dangerous. But we need to draw a line so that police can issue you a ticket. In terms of danger, there is no big difference between 74 mph and 76 mph. But you will get a ticket when you drive 76 mph. The same concept applies for hurricanes. Winds at 73 mph and 74 mph will cause similar damage, but they are defined as a tropical storm and a Cat-1 hurricane, respectively. In short, Saffir-Simpson Scale is just a qualitative measure of hurricane strength and allows us to better define the hurricanes.

2. Where are hurricanes most likely to form during the Atlantic hurricane season?

A hurricane is a gigantic system that requires lots of energy to maintain. Where does that energy come from? From warm ocean surface through evaporation. When water becomes vapor, it absorbs energy. This is a similar mechanism when you get out of swimming pool. You feel cool. It's not because the water is cool (the water is pretty hot in Miami), it's because the water evaporation takes energy away from your skin, which makes you feel cool. So, when ocean water evaporates, it takes energy away from the ocean surface and this is the energy supply for hurricanes. The higher the sea surface temperature, the easier for water evaporation. So, hurricanes like to form over the warm ocean surface. In the Atlantic Ocean, water is warmer in the west side than in the east side. This is the reason why you find many hurricanes in the Caribbean, Gulf of Mexico, and along US coast.

3. What was the highest wind speed ever recorded in a hurricane?

I believe it is Hurricane Hazel in 1954. The highest wind speed recorded is about 150 mph (240 km/h). It is the strongest hurricane ever recorded to date to strike so far inland.

4. What is the deadliest hurricane on record?

A 1900 hurricane slammed into Galveston, Texas killing 8,000 people. It was a category 4 hurricane, and it struck the island with sustained winds of 140 miles per hour. With no radar, tracking, or predictions, there were no preparations made for the storm. The highest elevation in Galveston in 1900 was 8.7 feet; the 15.7 foot storm surge covered the homes and businesses like an ocean. It cost $20 million at the time; in today’s money, the damage would have cost $700 million. After the hurricane, Galveston raised a sea wall and increased the grade of the island to prevent a recurrence of the tragedy.

5. Can hurricanes still form in the winter?

Normally, hurricanes will not form in the winter because sea surface temperatures are low. See Question # 2.