Heavy rain with thunderstorms this afternoon and evening KOAA Weather and last updated 2021-05-17 08:05:44-04 Todayâs Forecast: We're going to see a very active afternoon and evening across southern Colorado as strong to severe storms move out of the mountains and across the plains. Light rain overnight will continue through the early morning in areas like Fremont and El Paso Counties, but most of the region will start cloudy, foggy, and cool. Storms will develop this afternoon over the southern mountains around and just after lunch, growing stronger through the mid-afternoon to the end of the day. Storms will move east across the plains overnight, spreading out with heavy rain and a few severe threats.