Climate change adjustment

XRain statistics are based on precipitation measurements covering 2001 to 2020, inclusive. They describe what has happened in the past (historical conditions), but don’t predict what will happen in the future.

Users should use local guidance or IPCC AR6 (Intergovernmental Panel on Climate Change Sixth Assessment Report) projections to adjust precipitation statistics for the effects of climate change. IPCC AR6 predictions may be found at

Seasonal precipitation

The IPCC AR6 value “Total precipitation (PR)” can be used to scale seasonal statistics.

Extreme precipitation

In general, climate change will lead to an increase in the severity and the frequency of extreme precipitation events. By severity, we mean that a 50 year event under climate change conditions will be heavier than a 50 year event under today’s conditions. By frequency, we mean that an event that today occurs once in 50 years will occur more often under climate change conditions.

IPCC AR6 predictions include two variables of interest:

  • Maximum 1-day precipitation (Rx1day)
  • Maximum 5-day precipitation (Rx5day)

If you choose “Annual” as the season, these variables are the maximum 1-day and 5-day precipitation seen in each year.

To extract the percentage change for your location of interest, we recommend downloading the data as NetCDF and interrogating this file in your GIS software.

For more information see chapter 11.4 of IPCC AR6.