National Weather Service Forecast for: Johnstown CO
Issued by: National Weather Service Denver-Boulder, CO
Updated: 12:46 am MDT Jun 22, 2026
 
Overnight

Overnight: Mostly clear, with a low around 55. Calm wind.
Mostly Clear

 Monday

Monday: A 30 percent chance of showers and thunderstorms, mainly after 2pm. Mostly sunny, with a high near 90. Calm wind becoming east southeast 5 to 7 mph in the morning.
Mostly Sunny
then Chance
T-storms
 Monday
Night
Monday Night: A 20 percent chance of showers and thunderstorms before 8pm. Partly cloudy, with a low around 57. East wind 5 to 9 mph becoming south southwest after midnight. Winds could gust as high as 15 mph.
Slight Chance
T-storms then
Mostly Clear
 Tuesday

Tuesday: Sunny, with a high near 85. Breezy, with a north wind 11 to 17 mph becoming east northeast in the afternoon. Winds could gust as high as 28 mph.
Sunny and
Breezy then
Sunny
 Tuesday
Night
Tuesday Night: A chance of showers and thunderstorms before midnight, then a slight chance of showers. Mostly cloudy, with a low around 57. East wind 9 to 14 mph becoming light east southeast after midnight. Winds could gust as high as 22 mph. Chance of precipitation is 40%.
Chance
T-storms then
Slight Chance
Showers
 Wednesday

Wednesday: A 40 percent chance of showers and thunderstorms after noon. Partly sunny, with a high near 84.
Mostly Sunny
then Chance
T-storms
 Wednesday
Night
Wednesday Night: Showers likely and possibly a thunderstorm before midnight, then a chance of showers. Mostly cloudy, with a low around 56. Chance of precipitation is 70%.
Showers
Likely then
Chance
Showers
 Thursday

Thursday: A chance of showers and thunderstorms after noon. Mostly cloudy, with a high near 83.
Mostly Cloudy
then Chance
T-storms
 Thursday
Night
Thursday Night: A chance of showers and thunderstorms before midnight. Mostly cloudy, with a low around 56.
Chance
T-storms then
Mostly Cloudy
Lo 55 °F Hi 90 °F Lo 57 °F Hi 85 °F Lo 57 °F Hi 84 °F Lo 56 °F Hi 83 °F Lo 56 °F

 

Overnight
 
 Mostly clear, with a low around 55. Calm wind.
Monday
 
 A 30 percent chance of showers and thunderstorms, mainly after 2pm. Mostly sunny, with a high near 90. Calm wind becoming east southeast 5 to 7 mph in the morning.
Monday Night
 
 A 20 percent chance of showers and thunderstorms before 8pm. Partly cloudy, with a low around 57. East wind 5 to 9 mph becoming south southwest after midnight. Winds could gust as high as 15 mph.
Tuesday
 
 Sunny, with a high near 85. Breezy, with a north wind 11 to 17 mph becoming east northeast in the afternoon. Winds could gust as high as 28 mph.
Tuesday Night
 
 A chance of showers and thunderstorms before midnight, then a slight chance of showers. Mostly cloudy, with a low around 57. East wind 9 to 14 mph becoming light east southeast after midnight. Winds could gust as high as 22 mph. Chance of precipitation is 40%.
Wednesday
 
 A 40 percent chance of showers and thunderstorms after noon. Partly sunny, with a high near 84.
Wednesday Night
 
 Showers likely and possibly a thunderstorm before midnight, then a chance of showers. Mostly cloudy, with a low around 56. Chance of precipitation is 70%.
Thursday
 
 A chance of showers and thunderstorms after noon. Mostly cloudy, with a high near 83.
Thursday Night
 
 A chance of showers and thunderstorms before midnight. Mostly cloudy, with a low around 56.
Friday
 
 A slight chance of showers and thunderstorms after noon. Mostly sunny, with a high near 91.
Friday Night
 
 Partly cloudy, with a low around 58.
Saturday
 
 Sunny and hot, with a high near 98. Breezy.
Saturday Night
 
 Mostly clear, with a low around 59. Breezy.
Sunday
 
 Sunny, with a high near 93. Breezy.

 

Forecast from NOAA-NWS for Johnstown CO.