How much rain has actually fallen on metro Seattle — the last day, week, month and season, each against what is normal for that same stretch of the calendar — plus growing degree days, the frost window, and how dry the ground is underneath it all.
Daily precipitation and temperature are NOAA/NCEI nClimGrid-Daily area averages, by county. A rolling window’s normal is prorated across the months it spans — a 30-day window ending mid-September is part September and part August — so “% of normal” compares like with like rather than against a whole calendar month. Growing degree days accumulate from 1 January at base 50 °F. The frost window is derived from monthly normal lows, so it is month resolution, not a date. Drought is the Palmer index from NOAA’s Climate at a Glance.