I am curious if others have noticed an issue with datetime64 at the beginning of 1970. First: In [144]: (np.datetime64('1970-01-01') - np.datetime64('1969-12-31')) Out[144]: numpy.timedelta64(1,'D') OK this look fine, they are one day apart. But look at this: In [145]: (np.datetime64('1970-01-01 00') - np.datetime64('1969-12-31 00')) Out[145]: numpy.timedelta64(31,'h') Hmmm, seems like there are 7 extra hours? Am I missing something? I don't see this at any other year. This discontinuity makes it hard to use the datetime64 object without special adjustment in ones code. I assume this a bug? Thanks, Bob ps I'm using the most recent anaconda release on mac os x 10.6.8 which includes numpy 1.7.0. pss It would be most handy if datetime64 had a constructor of the form np.datetime64(year,month,day,hour,min,sec) where these inputs were numpy arrays and the output would have the same shape as the input arrays (but be of type datetime64). The hour,min,sec would be optional. Scalar inputs would be broadcast to the size of the array inputs, etc. Maybe this is a topic for another post.