National Weather Service Forecast for: McKinney TX
Issued by: National Weather Service Dallas/Fort Worth, TX
Updated: 1:26 am CDT Aug 20, 2026
 
Overnight

Overnight: Mostly clear, with a low around 82. South southwest wind around 10 mph.
Mostly Clear

 Thursday

Thursday: Sunny and hot, with a high near 105. Heat index values as high as 111. West southwest wind 5 to 10 mph.
Hot

 Thursday
Night
Thursday Night: A 20 percent chance of showers and thunderstorms before 10pm. Partly cloudy, with a low around 81. South southeast wind around 5 mph.
Slight Chance
T-storms then
Partly Cloudy
 Friday

Friday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny and hot, with a high near 105. Heat index values as high as 112. South wind around 5 mph becoming west southwest in the morning.
Sunny then
Slight Chance
T-storms
 Friday
Night
Friday Night: A 10 percent chance of showers and thunderstorms before 10pm. Mostly clear, with a low around 81. South wind around 5 mph.
Slight Chance
T-storms then
Mostly Clear
 Saturday

Saturday: Sunny and hot, with a high near 105. South southwest wind around 5 mph.
Hot

 Saturday
Night
Saturday Night: Mostly clear, with a low around 80. South wind around 5 mph.
Mostly Clear

 Sunday

Sunday: Sunny and hot, with a high near 105. South wind around 5 mph.
Hot

 Sunday
Night
Sunday Night: Mostly clear, with a low around 81. South southeast wind 5 to 10 mph.
Mostly Clear
Lo 82 °F Hi 105 °F Lo 81 °F Hi 105 °F Lo 81 °F Hi 105 °F Lo 80 °F Hi 105 °F Lo 81 °F

Extreme Heat Warning
 

Overnight
 
 Mostly clear, with a low around 82. South southwest wind around 10 mph.
Thursday
 
 Sunny and hot, with a high near 105. Heat index values as high as 111. West southwest wind 5 to 10 mph.
Thursday Night
 
 A 20 percent chance of showers and thunderstorms before 10pm. Partly cloudy, with a low around 81. South southeast wind around 5 mph.
Friday
 
 A 20 percent chance of showers and thunderstorms after 1pm. Sunny and hot, with a high near 105. Heat index values as high as 112. South wind around 5 mph becoming west southwest in the morning.
Friday Night
 
 A 10 percent chance of showers and thunderstorms before 10pm. Mostly clear, with a low around 81. South wind around 5 mph.
Saturday
 
 Sunny and hot, with a high near 105. South southwest wind around 5 mph.
Saturday Night
 
 Mostly clear, with a low around 80. South wind around 5 mph.
Sunday
 
 Sunny and hot, with a high near 105. South wind around 5 mph.
Sunday Night
 
 Mostly clear, with a low around 81. South southeast wind 5 to 10 mph.
Monday
 
 Sunny and hot, with a high near 104.
Monday Night
 
 Mostly clear, with a low around 81.
Tuesday
 
 Sunny and hot, with a high near 104.
Tuesday Night
 
 Mostly clear, with a low around 81.
Wednesday
 
 Sunny and hot, with a high near 102.

 

Forecast from NOAA-NWS for McKinney TX.