But today is cold with sleeting drips of rain. The light is flat and gray, but that's only a deterrent for a unimaginative sketcher!
Gray, flat light brings out subtle colors. Golds almost glow against grayed shadows. All of the oak tree leaves have turned brown, but on a gray day they show up in rich oranges and golds.
I used a very limited palette for this little rainy day sketch. The gray depths of the shadow are painted in cobalt blue, quinacridone red and touches of burnt sienna. I added a few wisps of tall pine trees in pthalocyanine green and azo yellow. The bright gold of the leaves are quinacridone gold, with touches of quinacridone red and cadmium yellow. A little wax crayon was used to preserve some of the whites, but on a rainy day, whites are dulled, with a bluish tinge. A bit of white gouache was better than the paper for these dulled flat whites.
Remember, flat light always means limited color and values. You don't get the sparkle of a sunny day. It's a muted, but still rich palette.
So the next day your sketching plans are ruined because of rain, look out your window and paint whatever you see. There is always something to paint for the imaginative sketcher!
What have you painted out your windows that you wouldn't have noticed otherwise?