numpy datetime and timedelta
Datetimes and Timedeltas — NumPy
https://docs.scipy.org/doc/numpy/reference/arrays.datetime.html
Tips
How can I make a python numpy arange of datetime - Stack Overflow
https://stackoverflow.com/questions/12137277/how-can-i-make-a-python-numpy-arange-of-datetime
find closest time from array
MetPy Mondays `#137
https://www.unidata.ucar.edu/blogs/developer/entry/metpy-mondays-137-finding-grib
code:python
times = np.array( ... )
desired_time = datetime.utcnow() + timedelta(hours=12)
delta_times = times - desired_time
idx_min = np.argmin(np.abs(delta_times))
timesidx_min