The Haines Index is an operational tool for evaluating the potential contribution of dry, unstable air to the initiation and growth of plume-dominated or erratic wildfires. This widely-used empirical index has three variants referred to as "low", "mid" , and "high" that partly account for differences in surface elevation. The index is calculated from temperature and humidity measurements at atmospheric pressure levels that differ for the three variants. A 40-year (1961-2000) climatology of the Haines Index was developed for North America (excluding Alaska and extreme eastern Canada). The climatology is based on gridded (2.5 degrees latitude x 2.5 degrees longitude) temperature and humidity fields for 0000 UTC from the NCEP/NCAR reanalysis. In addition to standard statistical summaries at annual, seasonal, and monthly temporal scales, the persistence of the Haines Index is also considered. The climatology illustrates the large spatial variability in the Haines Index both within and between regions using the different index variants.

To access the climatological maps, please select the:

1. Haines Index variant (low, mid or high)
2. summary period (annual, seasonal, or monthly) for which the statistics were calculated
3. statistical parameter
4. threshold values for the Haines Index

Note that there is a small box to check if you only want to see the statistics for the specific Haines Index region that you selected. If the box is not checked, the analysis for a particular variant will be displayed for all of North America.

Please see the web site for the USDA Forest Service Pacific Wildland Fire Sciences Lab for additional information on how to use the web-based Haines Index climatology.