DataSet.tmean(over='time', align='right', window=None)

tmean: Calculate the temporal mean of all variables.

Useful for: monthly mean, annual/yearly mean, seasonal mean, daily mean, daily climatology, monthly climatology, seasonal climatology

  • over (str or list) – Time periods to average over. Options are ‘year’, ‘month’, ‘day’. This operates in a similar way to the groupby method in pandas or the tidyverse in R.

  • align (str) – This determines whether the output time is at the left, centre or right hand side of the time window. Options are “left”, “centre” and “right”

  • window (int) – This determines the number of time steps to calculate the mean over to calculate over, on a non-rolling basis. This is useful if you need to calculate the mean every 5 days, for example.


If you want to calculate mean over all time steps. Do the following:

>>> ds.tmean()

If you want to calculate the mean for each year in a dataset, do this:

>>> ds.tmean("year")

If you want to calculate the mean for each month in each year in a dataset, do this:

>>> ds.tmean(["year", "month"])

This method will also let you easily calculate climatologies. So, if you wanted to calculate a monthly climatological mean, you would do this:

>>> ds.tmean( "month")

A daily climatological mean would be the following:

>>> ds.tmean( "day")