Table S2.

Linear trend in the relative fire weather season length and number of days of high fire potential (exceeding the 95th percentile of observations) per 37 y averaged over western forests from 1979 to 2015

MetricgridMETNo ACC gridMETERA–INo ACC ERA–INN1No ACC NN1
Trend in fire weather season length (percent) per 37 years
 KBDI50.0%*20.7%80.6**37.3%*13.7%–4.2%
 FFDI37.1%*7.9%57.8%**34.3%**19.5%*0.5%
 FWI33.6%*9.3%57.7%**41.3%**25.1%**11.7%
 ERC45.1%**38.4%**45.3%**40.5%**19.5%**16.6%*
 MEAN41.4%*19.1%60.4%**38.3%**19.5%*5.8%
Trend in number of days with high fire potential per 37 years
 KBDI12.7*4.926.0**10.011.3–2.9
 FFDI15.1**3.219.8**8.0*4.3–4.2
 FWI11.7*2.917.1**11.2**6.4*2.7
 ERC28.4**20.0**32.2**24.1**10.7*2.6
 MEAN17.0**7.823.8**13.3**8.2*–0.3
  • Columns labeled as “No ACC” indicate that these variables have been recalculated after subtraction of the CMIP5 ensemble-mean trends in temperature and vapor pressure. Trends are shown using the gridded meteorological dataset (gridMET) (50), ERA-INTERIM (ERA-I), and NCEP–NCAR (NN1). Asterisks indicate significant trends at the (*) 95% and (**) 99% levels. Significance was evaluated using a single-tailed test for trends.