It happens all the time, but I never like it.
Weather and light are conspiring right now to create a photograph that I can't possibly get to in time to record it..
Earlier in the day, I was preparing to walk out to the railroad right of way and await the failing of the light on the river. The tripod was packed, lenses cleaned, all was ready... and then the rain squalls moved in in earnest.
So I started in on laundry instead.
Walking back into the living room and looking out just now I realized that the light I was hoping for was there now and would not be in the fifteen minutes that it would take me to run out there and set up the gear.
Overall, it probably would have been a good day to camp out (literally, to avoid being soaked to the bone) and record the range of weather that we can get here in a day.
But you only know these things in hindsight.