Hurricane Season's Peak: Most Intense Mainland U.S. Hurricanes Hit in This 17-Day Period

There is a little-more-than-two-week period that has a notorious history when it comes to hurricanes. Based on lowest atmospheric pressure, the five most intense mainland U.S. hurricanes have all made landfall in a 17-day period between Aug. 17 and Sept. 2.

(MORE: Monsters of the Atlantic: The Basin's Category 5 Hurricanes)

In general, a lower pressure means a more intense hurricane in terms of its winds and overall destructive potential. Conversely, a higher pressure indicates a weaker system.

This 17-day period is just a nine-percent slice of the entire Atlantic hurricane season, which spans six months from June 1 to Nov. 30 each year.

These hurricanes also struck before the Sept. 10 climatological peak of the hurricane season.

(MORE: Where Every Hurricane Has Hit the U.S. Since 1985)

The meteorological reason for why the landfalls of the most intense mainland U.S. hurricanes are crammed into such a narrow window from late August into early September is somewhat speculative, however. Stu Ostro, a senior meteorologist for The Weather Channel, offers this possible explanation.

"The peak of the season, when the strongest hurricanes most commonly form, doesn't ramp up until mid-August. Then, after early September, there tends to be an increase in southward intrusions all the way to the Gulf of Mexico and Southeast Coast of things typical of autumn, such as cool air, dry air and dips in the jet stream that bring increased wind shear, all of which can disrupt hurricanes.

In a nutshell, the deeper into September you go, more factors become present that can cause hurricanes to not reach the mainland U.S. with the most extreme wind strength. However, they can still be very powerful and destructive from storm surge or rainfall, as well as wind. You only have to go back to Hurricane Sandy in 2012 for an illustration of extreme storm surge very late in October.

5 Most Intense Mainland U.S. Hurricanes

Ranked in order below are the five most intense Lower 48 U.S. hurricanes based on atmospheric pressure at landfall.

5. Indianola, Texas, 1886: Indianola took a devastating blow from a Category 3 hurricane in 1875 that killed hundreds. The town tried to bounce back, only to take an even stronger hit from a Category 4 hurricane on Aug. 20, 1886, the fifth-strongest hurricane to make landfall on the U.S. mainland. Most of the population left town, and the few who remained were scared off by a Category 2 hurricane just five weeks later. The post office closed in 1887 and Indianola ceased to exist as a town.

4. Hurricane Andrew, 1992: Andrew was a small hurricane, but it packed extreme winds, estimated to be Category 5 strength at landfall, along the southeastern Florida coast. The pressure at landfall was 922 millibars. The intense winds caused catastrophic damage in southern Florida, destroying or damaging about 125,000 homes.

3. Hurricane Katrina, 2005: Katrina made its first landfall near Buras, Louisiana, with a pressure of 920 millibars. It remains the lowest pressure on record for a Category 3 landfall. Instead of a focused core of powerful winds, Katrina's energy was distributed by a larger area of strong, but not as extreme, winds. The large field of strong onshore winds pushed catastrophic storm surge into the Mississippi Gulf Coast, peaking at 27.8 feet in Pass Christian, the highest surge on record in the U.S. The surge penetrated six miles inland across most of southern Mississippi, and up to 12 miles inland along bays and rivers. More than 200 people lost their lives in Mississippi, mostly due to the surge.

2. Hurricane Camille, 1969: At the time of its landfall on the night of Aug. 17-18, 1969, Camille had a pressure of 900 millibars. The exact wind speeds in Camille will never be known, as all wind-measuring instruments near the core of the storm were destroyed. Recent reanalysis of Camille suggests the storm had sustained winds in excess of 170 mph. The storm surge of 24.6 feet in southern Mississippi set a U.S. record that would later be surpassed by Katrina. Because Camille was more compact, the devastating surge focused on a narrower swath of coastline than that of Katrina. Camille's landfall was blamed for 143 deaths, and another 113 people perished in Virginia from flash flooding resulting from Camille's remnants.

1. Labor Day Hurricane (Florida Keys), 1935: With a pressure of 892 millibars at landfall in the Florida Keys, the Category 5 Labor Day hurricane of 1935 is the most intense hurricane on record to hit the U.S. The small hurricane underwent an astounding strengthening period from a Category 1 to a Category 5 as it moved from Andros Island in the Bahamas on Sept. 1 to the Florida Keys the evening of Sept. 2. According to NOAA, maximum sustained winds at landfall were estimated to be 185 mph. Storm surge reached 20 feet. The combination of winds and surge caused 408 fatalities, primarily among World War I veterans who were working on construction projects in the area.