Lenticular or dish-shapes clouds low in the atmosphere indicate strengthening winds and moisture laden air. The appearance of lenticular clouds generally mean that a storm will be approaching in the next 6-24 hours.
High, wispy cirrus clouds can be a signal of condensing moisture and these clouds very often increase in the sky before a weather event. Cirrus clouds can mean bad weather is coming within 24-36 hours. Cirrus clouds are often followed by lower clouds that will bring precipitation your way. Once those lower clouds arrive you may only have 6 or so hours before rain begins to fall. When these high clouds cover the sky they create a “milky” sky. This milky sky combined with strong winds is a strong signal that a storm is headed towards you.
Thunder Clouds or ‘Cumulonimbus clouds’ (anvil shaped) are clearly a sign of changing weather. You’ll have to determine wind direction to see if those thunder clouds are headed your way. In the mountains, in the summertime, it is very normal for thunderclouds to build via daytime heating and orographic lifting and drop precipitation and lighting on mountains at around 2-5pm in the afternoon.
Moon or sun ring
A ring around the sun during the day or the moon at night indicates that there is moisture in the air, creating that ring. That moisture is cirrostratus clouds that are often associated with warm weather fronts. These rings often signal a storm approaching within 72 hours.
Red sky in the morning
If you can see the western horizon at sunrise and you see red clouds in the sunrise, this is a very simple way of knowing that there are clouds headed your way. These clouds could be bringing rain upon your day.