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99th percentile of daily maximum temperature (warmest day of the season)

An expression of change in extreme temperature used in UKCP09. The UKCP09 projections provide information on the 99th percentile of daily maximum temperature on a seasonal basis, assumed to represent the warmest day of each season.

In detail

UKCP09 projects changes in climate extremes that are based on the 99th percentile. Assuming each season is 100 days long, the 99th percentile roughly corresponds to 1 day per season. Hence, this variable can be thought of as the change in the temperature of the warmest day of each season, and changes are provided in probabilistic terms by UKCP09 over land areas.

  • A complete list of climate variables for which probabilistic projections are available is given in Table 1.1 of the UKCP09 Climate change projections report. Some additional information about temperature is given in Box 1.2.

  • Information is also available on observed temperature. The UKCP09 Observed trends report provides details of recent trends in mean, maximum and minimum temperature, as well as days of air frost. The UKCP09 Extremes atlas provides details about daily extremes, heatwaves and coldwaves.