Weather Blog

Historically wet autumn? Not quite, but close

Historically wet autumn? Not quite, but close

So much for a dry El Nino autumn....

Instead, the autumn of 2012 is working its way up the charts among the wettest on record. It's still got a ways to go, but then again, the month of December still has a ways to go as well.

Below are two charts I've compiled for Seattle (at Sea-Tac Airport) showing the amount of accumulated rain between October and December (what I'm going to call autumn even through the actual season is shifted 10 days earlier). Right now we're not in the Top 20 but with more rain in the forecast, if December reaches close to its normal rainfall of about 5", we'll move into the Top 10.

I've also put together the wettest years on record at Sea-Tac. This feat, I believe, is more impressive because we essentially did this in 10 months, not 12 with no rain in August and barely any rain in September (0.03"). Our wettest year of 1950 (55.14") averaged 4.60" of rain per month, while if you take where we are as of Thursday (43.47") and divide by 10, you get 4.35" per month. If we add 3 more inches to December, that rises to about 4.64" per 10 months.

(This chart is now updated through Dec. 31)

Top 25 wettest October-to-Decembers at Seattle's Sea-Tac Airport:

     Year    Oct     Nov     Dec     Total

  1. 1955    6.60    8.96    9.50    25.06
  2. 2006    1.55    15.63   7.30    24.48
  3. 1998    3.48    11.62   8.98    24.08
  4. 1950    7.21    7.98    7.14    22.33
  5. 1996    5.54    5.23    11.20   21.97
  6. 2012    6.71    8.28    6.85    21.84
  7. 1995    3.93    10.40   6.37    20.70
  8. 1963    5.06    9.69    5.79    20.54
  9. 1975    7.75    5.07    7.66    20.48
  10. 1990    5.79    10.71   3.63    20.13
  11. 1973    3.31    7.99    8.33    19.63
  12. 2003    8.96    6.77    3.88    19.61
  13. 1958    3.99    8.07    7.15    19.21
  14. 2010    5.24    5.05    8.69    18.98
  15. 1968    4.32    5.86    8.55    18.73
  16. 1962    4.16    9.34    5.22    18.72
  17. 1947    8.95    3.62    6.02    18.59
  18. 2001    3.13    9.26    5.89    18.28
  19. 1966    2.92    6.85    8.31    18.08
  20. 1959    2.67    8.14    6.83    17.64
  21. 1953    4.43    7.22    5.92    17.57
  22. 1994    3.51    5.79    8.15    17.45
  23. 2009    5.54    8.96    2.75    17.25
  24. 1979    3.38    1.94    11.85   17.17
  25. 1999    2.26    9.60    5.06    16.92
  26. Avg:    3.48    6.47    5.35    15.30

How about for the entire year? We're in the Top 10 so far: (Average: 37.41")

            Year    Annual

  1. 1950    55.14
  2. 1996    51.69
  3. 1968    50.15
  4. 1953    49.42
  5. 2006    48.42
  6. 1972    48.36
  7. 2012    48.26
  8. 2010    46.99
  9. 1955    46.61
  10. 1959    46.52