Current status of heat unit / day degree accumulation from Jan 1 through May 2. For comparison, graph shows 2009 and 2007. As patrons recall, 2009 was a "late" year for many PNW crop harvests (similar, but not quite as late as 2008). For our purpose here, the 2007 figures are shown, as that year had relatively normal timing for most ag crops in the PNW. All figures are calculated using the same double sine,min/max temps formula. Your WxCafé™ will update in another month or so. For our Abbotsford patrons: values are similar to Bellingham. How to use this chart -- A typical PNW day at 70-75F will yield approx. 10-15 DD units. Divide the chart DD difference between years for your location by 12 to estimate how many days 'ahead' you are relative to previous years..