The phrase "temperature index" refers to a numerical scale or measurement that helps to assess or indicate how hot or cold something is. Full definition
The broad general agreement about trends in surface temperature indices is sufficient for our purposes. (judithcurry.com)
Growth increases and decreases appear in our sample above specific temperature index values (temperature thresholds), which occurred more frequently in the late 20th century. (deepclimate.org)
The annual cycle and spatial patterns of extreme temperature indices are generally well reproduced in both models but the magnitude varies. (pacificclimate.org)