Area burned variability in the province of Ontario, Canada, was inferred from 25 tree ring width chronologies covering A.D. 1781--1982 and distributed largely across the Boreal Shield. The area burned estimates account for 39.5% of the variance in the actual area burned recorded from 1917 to 1981 and were verified using a split sample calibration-verification scheme. The reconstruction showed that a positive trend in area burned from circa 1970--1981 was preceded by three decades during which area burned was amongst the lowest during the past 200 years. The area burned exhibited a trend toward increasing variance during the past century, recently reaching magnitudes similar to those seen prior to 1850. Signal analyses further identified the presence of two prominent periodic components in area burned that related to decade-to-decade variations. This will help to place the recent increase in area burned in a context relative to the long-term history of the province.