Tropical Storm Harold made landfall on Padre Island, Texas, this morning after forming in the Gulf of Mexico overnight, capping an extraordinarily busy 48 hours for an Atlantic hurricane season that saw three other storms form in quick succession.

Harold had already started to pummel parts of southern Texas with heavy rain, and was expected to deliver up to 6 inches of rainfall in isolated areas through early Wednesday, the National Hurricane Center said in an advisory.

The storm had already delivered up to 2 inches of rain in several places, including at Corpus Christi International Airport, said Bob Oravec, a meteorologist with the National Weather Service. Around 7 inches had fallen on Mustang Island, east of the airport, he said.

“It’s moving very quickly,” Oravec said, noting that he did not anticipate the heavy rainfall to last that long.

Meteorologists said the storm made landfall around 10 a.m. local time on Padre Island, a popular tourist area known for its beaches. Videos posted to social media appeared to show darkening skies and palm trees and street signs teetering in the wind. By 1 p.m., the core of the storm had moved inland, forecasters said. Harold was moving west-northwest at around 21 mph toward southern Texas and northern Mexico, they said. Several areas remained under tropical storm warnings and watches.

Harold, which follows the storms Emily, Franklin and Gert, is the first storm of the Atlantic Hurricane season to make landfall.

More than 1.2 million people along the eastern coast of Texas were under a tropical storm warning as of around 1:30 p.m. local time, according to the weather service. Close to 35,000 people in the state were without power, according to poweroutage.us.

Another tropical storm, Hilary, lashed the West Coast over the weekend. Of the three other storms to form since Sunday, only Franklin was expected to remain a threat to land into today, with tropical storm warnings issued for the southern coasts of the Dominican Republic and Haiti.

Harold had sustained winds near 45 mph, with higher gusts, the hurricane center said. Tropical disturbances that have sustained winds of 39 mph earn a name. Once winds reach 74 mph, a storm becomes a hurricane, and at 111 mph it becomes a major hurricane.

Tropical storm conditions, including tropical storm-force winds that could lead to some damage and power outages, and a 1-3-foot storm surge from the mouth of the Rio Grande to Sargent, Texas, are possible. Tornadoes are also likely across southern Texas through the afternoon.

There is at least some risk of excessive rains that produce rainfall amounts of 3-5 inches across southern Texas which could lead to isolated flooding, especially in areas with more complex terrain. Given the preexisting dry conditions across the region, the rains will likely be beneficial for many areas but excessive for some, given their intensity, forecasters with the Weather Prediction Center said.

The heavier rain will likely fall across northern Coahuila and northern Nuevo Leon in Mexico. Rainfall amounts of 4-6 inches and isolated amounts up to 10 inches are possible through Wednesday, especially across the mountainous terrain.

The Atlantic hurricane season started on June 1 and runs through Nov. 30.

In late May, the National Oceanic and Atmospheric Administration predicted that there would be 12 to 17 named storms this year, a “near-normal” amount. On Aug. 10, NOAA officials revised their estimate upward, to 14 to 21 storms.

There were 14 named storms last year, after two extremely busy Atlantic hurricane seasons in which forecasters ran out of names and had to resort to backup lists. (A record 30 named storms took place in 2020.)

This year features an El Niño pattern, which arrived in June. The intermittent climate phenomenon can have wide-ranging effects on weather around the world, and it typically impedes the number of Atlantic hurricanes.

In the Atlantic, El Niño increases the amount of wind shear, or the change in wind speed and direction from the ocean or land surface into the atmosphere. Hurricanes need a calm environment to form, and the instability caused by increased wind shear makes those conditions less likely. (El Niño has the opposite effect in the Pacific, reducing the amount of wind shear.)

At the same time, this year’s heightened sea surface temperatures pose a number of threats, including the ability to supercharge storms.

That unusual confluence of factors has made solid storm predictions more difficult.

“Stuff just doesn’t feel right,” said Phil Klotzbach, a hurricane researcher at Colorado State University, after NOAA released its updated forecast in August. “There’s just a lot of kind of screwy things that we haven’t seen before.”

There is solid consensus among scientists that hurricanes are becoming more powerful because of climate change. Although there might not be more named storms overall, the likelihood of major hurricanes is increasing.

Climate change is also affecting the amount of rain that storms can produce. In a warming world, the air can hold more moisture, which means a named storm can hold and produce more rainfall, like Hurricane Harvey did in Texas in 2017, when some areas received more than 40 inches of rain in less than 48 hours.

Researchers have also found that storms have slowed down, sitting over areas for longer, over the past few decades.

When a storm slows down over water, the amount of moisture the storm can absorb increases. When the storm slows over land, the amount of rain that falls over a single location increases; in 2019, for example, Hurricane Dorian slowed to a crawl over the northwestern Bahamas, resulting in a total rainfall of 22.84 inches in Hope Town during the storm.

Other potential effects of climate change include greater storm surge, rapid intensification and a broader reach of tropical systems.

This article originally appeared in The New York Times.