October means storms hit Texas from Pacific
The Atlantic hurricane season lasts quite a long time, from the start of meteorological summer on June 1 all the way to the last day of meteorological fall on Nov. 30. However, the number of hurricanes or tropical storms from the Atlantic Ocean or Gulf of Mexico that make landfall in Texas decrease substantially as we head into October and November, the tail-end of the season.
Texas still sees tropical moisture during these fall months, but a key difference is that these storms tend to move into the state not from its seashore, but from a completely different direction. Instead of striking the Texas Gulf Coast directly, hurricanes in October often make landfall on the west coast of Mexico, and the remnants of these storms can generate heavy rain and flooding in parts of Texas, including San Antonio.
What’s the difference?
Generally speaking, when you think of Texas hurricanes, you probably think of storms developing somewhere in the Atlantic Basin, strengthening in the Gulf of Mexico, and striking the Texas coastline. These are storms that tend to be the most devastating to hit the state, both in terms of damage and lives lost.
Many of the most famous storms to hit the state have followed this script, such as Harvey in 2017, Ike in 2008, and Rita in 2005. All three of these hurricanes also made landfall late August or during the month of September, generally considered to be the peak of hurricane season.
But do you remember Pamela in 2021, Patricia in 2015 or Madeline in 1998? Some Texans might; but for the most part, these are not household names. These storms developed in the eastern Pacific Ocean, not the Atlantic, and impacted Texas in the month of October.
By the time the remnants reach Texas, Pacific storms like these are no longer a wind or storm surge threat, but they can produce very heavy rains and devastating flooding.
Why does the shift occur?
As Texas transitions from late summer to early fall, the weather pattern in the upper atmosphere starts to shift. The polar jet stream in Canada slowly moves a bit to the south. Because of that, areas of low atmospheric pressure and their associated cold fronts have a better chance of affecting the Lone Star State by October.
As cold fronts move through Texas more frequently, they act as barriers and can steer Atlantic-based tropical systems away from the state and keep them much farther east. This is why the eastern Gulf Coast and the U.S. East Coast are more likely to see direct landfalls than the Texas Gulf Coast by the time October and November come around.
Notable October storms
Hurricane Pamela: Just two years ago in October 2021, Pamela made landfall on the west coast of Mexico as a Category 1 hurricane. It weakened quickly, but its remnants provided moderate rainfall to parts of Central and South Texas. Between Oct. 13-15, San Antonio recorded 4.22 inches of rain, and Austin recorded 2.92 inches.
Hurricane Patricia: This historic hurricane rapidly strengthened in the eastern Pacific Ocean in late October 2015 and peaked with 215-mph wind speeds, the highest ever recorded worldwide. Patricia weakened to a Category 4 storm before making landfall on Mexico’s western coast. It continued to weaken before its remnants made their way into Texas.
Flooding rains soaked many areas across Texas. Austin and San Antonio received 4 to 6 inches of rain from Oct. 23-25. Houston picked up 7.58 inches of rain. But those totals pale in comparison to a few areas farther north. Corsicana received 21.05 inches of rain as a result of Patricia’s residual storms, forcing a closure of Interstate 45. Hurricane Madeline: Back in 1998, Madeline was not a strong hurricane. It peaked as a Category 1 storm off the west coast of Mexico, and it actually never even made landfall. However, moisture from Madeline interacted with a stalled cold front and produced one of the worst flooding disasters in Southcentral Texas history.
From Oct. 17-19, San Antonio picked up 15.61 inches of rain, including a record 13.35 inches in 24 hours. Austin picked up 8.72 inches of rain over the same three days. The highest rainfall amounts were between the two cities, though. An area just south of San Marcos recorded more than 30 inches of rainfall.