Spring
Today is the first day where the sun is in the sky more than 50% of the day. This happens before the equinox because of refraction effects of the earth's atmosphere and, I suppose, because the sun is not a point source of light.
That and seeing Sirius so far to the west in the night sky are my first firm signs of spring and the promise that despite our miserable weather for the past couple of months, warmth and green and sunshine are coming soon.