The National Climate Assessment has some interesting things to say about Hawaii, like this: In Hawai'i, average precipitation, average stream discharge, and stream baseflow have been trending downward for nearly a century, especially in recent decades. I see four NOAA climate regions in the state: Hilo (1950), Honolulu (1905), Kahului (1955), and Lihue (1939).  The start of continuous records is given in parentheses.  Thus, there is only one region (Honolulu) in Hawaii that has records dating back "nearly a century," and precipitation varies widely among the regions.  Precipitation at Hilo averages about 7-fold higher than at Honolulu. There is also a very poor correlation (r2=0.11) between annual precipitation at Honolulu and Hilo, so if you want to try and extend the precipitation record back in time at Hilo using Honolulu as a proxy, the quality of the results will be poor at best. But according to the NCA, "average precipitation...(Read Full Post)