Weather can be sunny, stormy, dreary or unpredictable but then so, too, can your mood. The way you feel on any given day may actually be intricately tied to the weather forecast in ways science is only beginning to understand.
Many people are now aware that spending time outdoors on a sunny day, and allowing the sun to shine on your bare skin, is necessary for your body to produce vitamin D, which also plays a role in serotonin production.
A sunny day can make you feel inexplicably happy, but only if you can frolic outdoors.