This paper describes forest fires and weather in Alaska, North America and Sakha, Eastern part or Far East Siberia. Mean air temperature change from 1830 in Yakutsk, Sakha clearly showed that there is a temperature rise. Especially, temperature rise from 1980's is remarkable in Yakutsk. On the other hand, precipitation trend from 1890 shows that precipitation is gradually decreasing from 1980's. Forest fire histories from 1956 in Alaska and Sakha show that average burnt area become larger and larger from 1990's. This is because boreal forest is now very flammable due to higher air temperature and lower precipitation conditions.