India's critical wet monsoon season has started

The India Meteorological Department (IMD) has officially declared the onset of the monsoon over the state of Kerala. The monsoon, which usually starts on June 1, is a few days late. But while the onset date is important, the overall forecast is much more crucial.

"Southwest monsoon seasonal rainfall over the country as a whole is most likely to be normal," the IMD said in a press release. "Quantitatively, the monsoon seasonal rainfall over the country as a whole is likely to be 101% of the Long Period Average with a model error of plus or minus 4 percent." The Indian weather agency classifies a monsoon as normal when total rainfall from June through September falls within the range of 96% to 104% of average. From 1961 to 2010, that long period average equates out to 88 cm total, or 34 inches.