Excessive Rainfall and Potential Tropical Cyclone in the South; Severe Thunderstorms in the Midwest

Excessive rainfall may produce locally considerable flash flooding over parts of the northwestern Gulf Coast, lower Mississippi River Valley, and Deep South through Thursday. Potential Tropical Cyclone One is forecast to become a tropical storm (Arthur) as it moves along or just off the northwestern Gulf coast through Wednesday. An outbreak of severe weather is forecast in the Midwest Wednesday. Read More >

Hazardous Weather Conditions

Extreme Heat Warning in effect from June 18, 12:00 PM CDT until June 18, 08:00 PM CDT

Current conditions at

San Marcos, San Marcos Municipal Airport (KHYI)

Lat: 29.89°NLon: 97.86°WElev: 597ft.

Fair

74°F

23°C

Humidity	97%
Wind Speed	E 3 mph
Barometer	29.79 in (1008.1 mb)
Dewpoint	73°F (23°C)
Visibility	10.00 mi
Last update	17 Jun 12:56 am CDT

More Information:

Local Forecast Office More Local Wx 3 Day History Hourly Weather Forecast

Extended Forecast for

4 Miles SSW San Marcos TX

Extreme Heat Warning June 18, 12:00pm until June 18, 08:00pm

Click here for hazard details and duration

Extreme Heat Warning

Overnight
Low: 73 °F
Mostly Cloudy
Wednesday
High: 91 °F
Decreasing
Clouds
Wednesday Night
Low: 77 °F
Increasing
Clouds
Thursday
High: 96 °F
Decreasing
Clouds
Thursday Night
Low: 79 °F
Partly Cloudy
Juneteenth
High: 93 °F
Mostly Cloudy
then Slight
Chance
T-storms
Friday Night
Low: 77 °F
Chance
T-storms
Saturday
High: 91 °F
Chance
Showers then
Chance
T-storms
Saturday Night
Low: 77 °F
Slight Chance
T-storms

Detailed Forecast

Overnight

Mostly clear early, then becoming mostly cloudy, with a low around 73. Calm wind.

Wednesday

Mostly cloudy, then gradually becoming sunny, with a high near 91. Heat index values as high as 103. Calm wind becoming south southeast around 5 mph in the afternoon.

Wednesday Night

Increasing clouds, with a low around 77. South wind 5 to 10 mph.

Thursday

Mostly cloudy, then gradually becoming sunny, with a high near 96. Heat index values as high as 115. South wind 5 to 15 mph, with gusts as high as 20 mph.

Thursday Night

Partly cloudy, with a low around 79. South southeast wind 5 to 15 mph, with gusts as high as 20 mph.

Juneteenth

A 20 percent chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 93. East southeast wind 5 to 10 mph.

Friday Night

A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 77. South southeast wind 5 to 10 mph.

Saturday

A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 91. South southeast wind 5 to 10 mph.

Saturday Night

A 20 percent chance of showers and thunderstorms before 1am. Partly cloudy, with a low around 77. South southeast wind around 10 mph.

Sunday

Mostly sunny, with a high near 93.