We are now entering the time of year when I become obsessed with daylight gains, an obsession I’ll hold on to through at least February. While January is long and cold it hits a few cool milestones that can brighten up the season.

This weekend for example, we hit perihelion, the day when the earth was closest to the sun. Relatedly, we hit the point where we are gaining daylight in both the morning and the evening. We started gaining back evening light in early December (about 2 weeks before the solstice), but at a slower rate than we were losing morning light. At the solstice this reversed: we kept losing morning light but at a slower rate than we gained evening light. Now we are gaining both evening and morning light, so our overall light gain becomes more noticeable. At least in the Boston area, this means Monday is the first day we gain a full extra minute of sunlight in one day. By the end of January, we’ll be gaining over 2 minutes a day.

A meteorologist on Facebook put up this graphic that shows how much daylight each region of the country can expect to gain total during January:

Obviously the regions that had the shortest days to begin with will gain the fastest, but it’s interesting to see where the cutoffs are.

Overall if you want to track your own daylight gains, this site is the one I use. It gives me some nice data to hold on to as we continue to slog through winter.