A common misconception about shooting portraits is that going outdoors to shoot on a “beautiful” day will result in “beautiful” photos. This is not necessarily the truth. What we call a beautiful day usually consists of a cloudless blue sky and prominent sunlight. This is great for the sky and if you are shooting landscapes or textures it might make for a useful shooting scenario.
But harsh, direct sunlight is not very flattering to the human face. It casts dark shadow on even the smallest imperfection of the skin, highlighting bumps, scars, wrinkles, etc. You can look in the mirror in the relatively dim tungsten lighting of your bathroom vanity and think you look just fine but exposed under the intense, hard light of the sun your features will come out looking significantly more distorted.
You’ll get much better results waiting until a nice, thick cloud-cover rolls into town. On an overcast day, the clouds function to scatter the sun’s rays, providing an even, non-directional source of light. This eliminates the shadows that exaggerate facial imperfections while retaining most of the exposure-friendly brightness of daylight. And as long as you choose a suitable background and avoid getting the cloudy gray sky in your frame nobody will suspect you shot such “beautiful” photos on such an “ugly” day.