Check your highest recorded temps for Seattle and lowest recorded temps for Seattle. I live here and I can say they are totally wrong. Che
Check your highest and your lowest recorded temps for each month for Seattle. I live here and I can say that many of your numbers are totally wrong. You have about 80 degrees F as the highest recorded and 27 F as the lowest. The actual figures are more like 103 degrees F (July 29, 2009) and 0 degrees F (sometime around 1950 I think.)
I have seen other mistakes too. Nice job making your site look modern but please double-check your data.