IMD expects above-normal heatwave days through May, after a dry February

On March 1 the India Meteorological Department released its outlook for the coming three months and it was not encouraging. The department expects above-normal heatwave days during the March to May period, with isolated heatwaves already flagged for parts of Gujarat and Andhra Pradesh in March itself.

The forecast arrives after a dry February. The IMD's own seasonal bulletin attributes part of the current spell to deficient rainfall over parts of the country, which leaves less soil moisture and fewer clouds to hold heat back during the afternoon.

• Heatwave days for March to May are forecast to be above the seasonal normal.
• Isolated heatwave conditions are likely over some parts of Gujarat and Andhra Pradesh during March.
• Maximum temperatures are expected to be above normal on 3 to 15 days across most of the country during March.
• February rainfall deficits form part of the background to the forecast.

What actually counts as a heatwave

The threshold matters, because a heatwave is not simply a hot day. Under the department's criteria a heatwave is declared when the maximum crosses 40 degrees Celsius in the plains, with lower cut-offs for coastal and hill stations, and a severe heatwave requires the maximum to run well beyond that. Counting days against those thresholds is how the seasonal forecast is expressed.