Difference Between Partly Cloudy and Mostly Sunny

Partly Cloudy vs Mostly Sunny

If you have seen a weatherman predict the weather of a particular area on TV, you must have seen him describe it as partly cloudy or mostly sunny. This makes you wonder if he is saying or talking about the same weather in two different ways as partly cloudy also implies mostly sunny conditions, isn’t it? It is often the difference between being a pessimist and an optimist, as one person calls a glass half filled with water as half empty while another person who is an optimist treats the glass as half-full. The weather prediction makes use of terms like partly sunny, partly cloudy, mostly sunny, and mostly cloudy that makes people more confused. This article attempts to clear this confusion.

Whether a weatherman makes use of the phrase partly cloudy or mostly sunny, there is no need for any confusion as there is a definition of all such terms as far as National Weather Services is concerned. When partly cloudy is used, it means that there may be a 30-70% cloud cover in the sky. When people hear the phrase partly cloudy, they tend to perceive clouds rather than the sun, and even if the cloud covers may be just 30% leaving the skies open and sunny, people think negatively as it being a cloudy day. Partly sunny is used by weathermen in a similar way, but used to be applied during daytime, emphasizing sunshine. But people tend to think more of sun than clouds even if the weatherman uses partly sunny to describe the weather during day time. To be precise, mostly sunny means less than 10% cloud cover, while mostly cloudy means more than 90% of skies covered by clouds.


So, partly cloudy is mostly sunny while partly sunny is mostly cloudy. If we speak in a continuum, to speak of weather conditions from least cloud cover to most cloudy conditions, the terminology used by weathermen is sunny, mostly sunny, partly cloudy, partly sunny, mostly cloudy, and finally cloudy. If you hear sunny weather, you can expect clear skies with warm and sunny conditions with less than 10% of cloud cover in patches. On the other hand, cloudy weather conditions refer to dark and dull weather conditions with sky covered with cloud all over and sun peeping out at some places from behind the cloud cover.