Temperature related variables

Heating degree days


Figure 10 - Heating degree days for Scottish regions each year from 1961 to 2003, with smoothed curves to show a running average.

Table 6 - The changes in heating degree days (HDD) between 1961 to 2003. Values in bold show that we are 95% confident (statistically) that the change is part of a measurable trend.


North Scotland East Scotland West Scotland Scotland
Heating degree days -9.2% -10.7% -11.3% -10.2%


Regional trends


  • Typical figures at the start of the 1961 to 2004 period were about 3200 HDD a year for North and East Scotland, and 2900 HDD a year for West Scotland.
  • In all areas of Scotland, the number of heating degree days has reduced and this appears to be part of a clear downward trend.
  • These trends are consistent with the temperature trends we have already described.

Spatial trends


  • The pattern within the HDD map is similar to that for average temperatures with the southerly, coastal and lower lying areas showing the greatest change.
  • There are areas in the Shetlands and the Outer Hebrides showing large reductions.

Future Trends


  • In the UKCIP02 scenarios, heating degree days are expected to reduce by 15% to 40 % by the 2080s. Changes are expected to be greatest in southern and eastern Scotland.
  • The pattern of change we see from analysing different variables is consistent with this. However, the changes so far (10.2% for Scotland as a whole) are not as great as those expected for the future.

Figure 11 - Pattern of change in heating degree days (as a percentage), from 1961 to 2003.