San Antonio does get rain often, but it is rare for it to rain for more than three days straight.

And once heavy rain starts, flooding can occur in less than half a day, submerging roads.

This time, a flood advisory has been issued for the entire area due to rain forecasts from Thursday night through Friday.

There are over 150 areas in Bexar County known as 'low water crossings.' These can quickly become submerged when it rains heavily.

Even if they appear shallow, the current can be strong enough to sweep vehicles away.

One common point of confusion is the difference between a flood 'advisory' and a 'warning.' A warning means that a dangerous situation is already occurring.

In contrast, an advisory like this one means that conditions are favorable for flooding. It indicates that flooding could happen at any time.

Last year, in June 2025, a sudden downpour resulted in the deaths of 13 people.

Most of these individuals were swept away while driving, illustrating how dangerous the assumption of "this should be fine" can be.

There are certain areas to avoid. The intersection of US 281 and Basse Road frequently floods due to overflow from Olmos Basin.

Near Pinn Road and Highway 151, water rises quickly due to Leon Creek.

The area around Interstate 35 and Seguin Road is dangerous because of Salado Creek, and the section of Old Grissom Road and Culebra often sees road closures.

Dreamland Drive is also a frequent problem area. In 2019, a bus was trapped in water, requiring a rescue operation.

This rain is affecting more than just the roads. Schools are also impacted.

North East, Northside, and Judson ISD are experiencing delays in bus operations or changes to some routes.

Southwest ISD is facing similar issues. Schertz-Cibolo-Universal ISD has even decided to close schools.

The flood warning has now been expanded to include Bexar, Comal, Guadalupe, and Medina counties.

The weather service reports that rain and heavy showers will continue throughout the day. There is a particular need for caution due to the potential for flash flooding, where water can rise suddenly.

There are also forecasts for possible hail and strong winds. On rainy days, it's better to avoid travel than to take risks.

On a positive note, it's the weekend. After the rain passes, the weather is expected to clear up. Morning temperatures will be in the 50s, and daytime highs will drop to the 70s, leading to some of the most pleasant weather in May.