In July 2015, we released an improved version of our daily (D2) and monthly (M3) precipitation grids. One of the improvements involved post-processing the grids so that the daily grid values summed to the monthly values. We recently discovered that a few of those grids did not undergo this post-processing. They have now been fixed. We recommend that the affected grids be re-downloaded at your convenience. They are:

Daily grids: June 1-30, 2015

Monthly grids: December 2015 - April 2016

What differences can be expected? The daily grids will change little east of the Rockies, but there may be changes, mainly in drier areas, from the Rockies westward. The opposite can be expected from the monthly grids; they will change very little from the Rockies westward, but there may be changes in drier areas east of the Rockies. Only precipitation grids are affected.