Heavy rainfall continues to batter India's west coast — Gujarat, Maharashtra, Kerala, Goa and parts of Tamil Nadu have received huge amounts of rain in the past week. The Avalanche region in the Nilgiris on Thursday set a record for the highest amount of rainfall received in a 24-hour period.

An analysis of IMD data for the past five years shows that several areas received an 'Excess' (20-59% more rainfall than normal) or 'Large Excess' (60% or more rainfall than normal) in the same or similar period -- June to the end of August first week. As can be seen in the chart below, Madhya Maharashtra division received 65% more rainfall than average.

However, an interesting aspect is that the all-India average for the period between June 1 (expected onset of the Southwest Monsoon) and August 7 is 5% below average. This means that though many regions received excess rainfall, several didn't, even within the same region.

For example, though Madhya Maharashtra received excess rainfall, Vidarbha and Marathwada got below normal rainfall. Similarly, despite heavy rains in parts of Tamil Nadu, the State as a whole received 30% less rainfall than normal.

One of the reasons for the lower average despite heavy rains over the past week is that the onset of the monsoon was delayed this year. The country missed out on days of rainfall initially; hence the heavy rain has just played catch-up on the cumulative rainfall several regions should have received till date.

The graph below shows that 13 out of 36 sub-divisions had an excess or large excess of rainfall between August 1 and August 7. However, this number dropped to four between June 1 and August 7.

It should also be noted that in the 1-week time period, 15 sub-divisions registered a deficit or large deficit of rainfall.

The maps below make it clearer. The first map below shows the rainfall from August 1-7. As it can be seen, while the west coast has received huge amounts of rain, several other parts have received deficient rainfall in the corresponding period.

The second map shows the cumulative rainfall from the start of the monsoon to August 7. Here, we see that considering the longer time span, several regions have received only normal rainfall.