NCDC Louisiana year-to-date mean temperatures with five year running mean in red. Louisiana warmed from 1895 to 1950, cooled for 15 years, and then warmed again until the late 1990s. Fifteen of Louisiana’s twenty warmest years occurred before 1960. The warmest year was 1911, when CO2 levels were 300 ppm. Even with USHCN upwards adjustments of recent data and downwards adjustments of past data, Louisiana has not shown any warming.