On a perusual of the monthly rainfall charts of Cherrapunjee given one can observe that there are cyclic low rainfall years at Cherrapunjee. The lowest in the above-mentioned years was in 1962 at 6,807.0 mm. The highest rainfall received in the recorded rainfall history was in the year 1974 at 24,555.3 mm. If we compare the annual rainfall of recent years at Cherrapunjee with the average annual rainfall of the place in the last 33 years (1973 - 2005) that is 12,028.6 mm, it is evident that there is no such thing as the rainfall has diminished much these recent years. Rev. Fr. Christopher Becker SDS (Germany) writing about Cherrapunjee of those days between 1890-1915 says "the rainfall at home is about sixty centimetres per year, but the average rainfall at Cherrapunjee during the last thirty years has been nearly twelve metres (488" - i.e. 12512 mm). There were several years when the rainfall was more than fifteen metres". When we analyse the daily rainfall data over recent 23 years, it can be surmised that the intensity of rainfall has increased compensating for any reduction, if any, in the number of rainy days or duration of rainfall. For the common man, if it rains in a drizzle or a normal downpour for a longer period of time or more number of days, it may appear that it has rained much but heavy downpours for short duration or for a fewer days can in fact contribute more rainfall than many days of drizzle or normal rainy days.
In 2004 we had a similar situation. The first pre-monsoon showers normally come by 10th March at Cherrapunjee. In 2004 there was no sign of rain till 9th March. On the 10th there was a mild drizzle to keep the date. March was going dry in the following weeks. Then in the last week we had good showers that took the total rainfall for March to 1,119.6 mm against the average rainfall for March of 304.7 mm. Thus, March 2004 received 367% of the average rainfall for March. And that too, was almost delivered in just one week. This year, May 2006 was going very dry till 26th May 2006. Only 27% of the rainfall for May was received till 26th May 2006. The next five days received 1750.6 mm. That is much more than the average for May, which is 1351.7 mm. A person visiting Cherrapunjee during those days having no rain finds that his perception of Cherrapunjee as raining always is belied. But it is a fact the rains had been abundant for the said months March, 2004 and May 2006. Add to this the fact of lack of correct information. The tourists become an easy prey for the taxi driver who doubles up as guide to enlighten the tourist that these days heavy rainfall has shifted to another place called Mawsynram. Mawsynram is hardly about 15 km aerial distance from Cherrapunjee and both the places are on the edge of the same valley, but being on another parallel range is reached by road from Shillong, which involves a total drive of another about 100 km from Cherrapunjee. It is another matter that almost invariably, when it rains at Mawsynram it rains also at Cherrapunjee because the clouds fly across the Sylhet plains to hit the southern ridges of Khasi Hills. Scientific truth is sacrificed at the altar of business expediency and the myth is kept going on. Often heavy rainfall occurs at night and early mornings. Often times, tourists visiting Cherrapunjee on a day visit from Shillong are not able to experience rainfall at Cherrapunjee during their short duration visit to Cherrapunjee and thus miss out most to experience the magic of the monsoon at Cherrapunjee.
The average annual rainfall around the world is about 1000 mm. One has to appreciate that Cherrapunjee gets more than 12 times the average rainfall of most of the places around the world. Shillong which is just 30 km north of Cherrapunjee by aerial distance falls in a rain shadow area and gets about one sixth of the rainfall at Cherrapunjee. When you drive from Shillong to Cherrapunjee at about half way (30 km from Shillong), you come to Mawjrong village where All India Radio has erected huge masts for broadcasting radio signals. Immediately after the village, as you near Mawkdok suspension bridge where the deep valleys begin, you can notice perceptible change in weather conditions during the monsoon months. It could be bright and sunny till that place and immediately as you cross into the gorge area you drive into clouds or into rain. Sometimes, you can have rainy weather till that place and as you reach Mawkdok you can find that it is bright and sunny on the other side.
During monsoon months thick rain clouds hug the hills from Mawkdok onwards and driving becomes very difficult after dark with zero visibility conditions. All one can do is to keep the white center line on the road in between the wheels to be sure that you are driving on the road instead of flying into the gorge or dashing into the rock walls. Even the white dividing lines are visible only two or three at the most at a time. When PWD-Roads have failed to repaint the dividing lines on the road as they fade from use, while driving in bad weather conditions with poor visibility, one has to stick one's head out to see the edge of the road alongside your vehicle and judge the need to turn the steering so that the vehicle continues to travel on this winding road. Sometime back PWD-Roads had installed 'cat's eye' road markers at some turns in the road. These days few remain. During the monsoon months, we, therefore, recommend that you reach your destination at Cherrapunjee before it is dark.
Usually the monsoon rains recede by the first fortnight of October. November, December, January and February have no or nominal rainfall. The odd rainfall is usually influenced by low-pressure systems over adjacent areas or cyclonic depressions over the Bay of Bengal.