This is from data downloaded for all of 2015 from MesoWest at the Hilo airport. Barometer is trustworthy because for safety reasons the airport barometer must be regularly calibrated.
Each day was broken out as separate data in Hawaii Standard Time. Since each data point is not always taken at the same exact time, each days’ data was then interpolated using a cubic spline so the data points could be lined up and averaged together. The result was multiplied by 0.67 to make the average match that from Willis’ Manua Loa data.