Extreme value statistics are used primarily to quantify the stochastic behavior of a process at unusually large (or small) values. Particularly, such analyses usually require estimation of the probability of events that are more extreme than any previously observed. Many fields have begun to use extreme value theory and some have been using it for a very long time including meteorology, hydrology, finance and ocean wave modeling to name just a few.
The Extremes Toolkit (extRemes) is an interactive program for analyzing extreme value data using the R statistical
programming language. A graphical user interface is provided (using the tcltk package), so a knowledge of R is not
necessarily required. Included from this website is a tutorial that explains how the toolkit can
be used to treat weather and climate extremes in a realistic manner (e.g., taking into account diurnal and annual cycles,
trends, physically-based covariates).