The possibility of thunderstorms is back in the weather forecast for the next couple of days.

The National Weather Service says cold temperatures in the upper atmosphere is creating unstable weather conditions and an increased chance of rain and possibly thunderstorms and snow on Big Island summits today and Tuesday.

Forecasters say the Big Island could get heavy showers tonight and the chance of thunderstorms will spread to other islands today and Tuesday.

Honolulu’s forecast calls for mostly cloudy skies with scattered showers. Monday should be mostly cloudy with windward and mauka showers in the morning and the chance of heavy showers and thunderstorms in the afternoon through Tuesday.