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Places in the World that have Reported 40”+ (1016 mm) of Rainfall within 24-hours<

By: Christopher C. Burt, 9:47 PM GMT on October 17, 2013

Places in the World that have Reported 40”+ (1016 mm) of Rainfall within 24-hours

The recent amazing rainfall total of 32.44” (824 mm) from Izu Oshima Island on October 15th, has prompted me to look at what places in the world have measured 24-hour rainfalls of 40” (1016 mm) or more. There seems to some debate as to whether Japan has ever measured such and the list of such places is a short one.

It has been reported that the 824 mm rainfall on Izu Oshima that fell on the calendar day of October 15th was the 3rd greatest 24-hour rainfall on record for Japan (at least measured at an official JMA site). The two heavier falls being 851.1 mm (33.51”) at Yanase, Kochi Prefecture on July 19, 2011 and 844 mm (33.23”) at Takeshi, Nara Prefecture on August 1, 1982. However, I believe Izu Oshima may have actually received as much as 850 mm (33.46”) in a 24-hour period of October 14-15. There have been heavier 24-hour (and calendar day) rainfalls in Japan according to scientific literature (ref: ‘The Climate of Japan’ edited by Elichiro Fukui, Elsevier publications, 1977). In this book the following are listed as Japan’s greatest 24-hour precipitation events:

1109.2 mm (43.67”) Saigo, Nagasaki Prefecture July 25-26, 1957

1011 mm (39.80”) Mt. Odaigahara, Nara Prefecture Sept. 14, 1923

997.4 mm (39.27”) Hase, Nagasaki Prefecture July 25-26, 1957

976.2 mm (38.43”) Zenki, Nara Prefecture Sept. 13, 1954

963.9 mm (37.95”) Mt. Odaigahara, Nara Prefecture July 29, 1946

The storm of July 25-26, 1957 was a result of a tropical storm colliding with what is known as a ‘Bai-u’ : a cold front draped over Japan with deep moist tropical air overrunning it and resulting in tremendous precipitation amounts. This is similar as to what occurred last Tuesday in Japan. Flooding from the 1957 event resulted in the deaths of almost 1000 people.

There is also a report of an even greater rainfall of 1138 mm (44.80”) in 24 hours at a site called ‘Hiso’ in Tokushima Prefecture on September 11-12, 1976 but I can not find any scientific references to this event nor any information about the site itself. Maximiliano Herrera has looked at official JMA data for nearby sites and it seems to be a dubious figure (as do the other sites listed in Dr. Fukui’s book).

Below is a list of all the places in the world that have reportedly received at least 40” (1016 mm) of precipitation in a single 24-hour period. It should be noted that some of these are of questionable veracity (especially those I’ve marked with an asterisk ‘*’). Also, the exact amounts vary from source to source. For most weather sites, accurately measuring such prodigious rainfalls over such a short time span is problematical. Places that ‘regularly’ see such rainfall, like on Reunion Island in the Indian Ocean, have special recording gauges to accommodate such rainfalls but most sites do not.

A photograph of Cilaos on Reunion Island off the coast of Africa in the Indian Ocean. This site may be where the heaviest 24-hour rainfall ever measured on earth occurred (73.62”/1870 mm) during a tropical storm on March 15-16, 1952. The figure, however, is not acknowledged by Meteo France which maintains climate data for the island. Photo from Wikicommons.

For example, the 43” reported from Alvin, Texas during Tropical Storm Claudette on July 25-26, 1979 was measured by a resident, Paul Davison, at his home using a household rain gauge. He actually reported a 45” storm total of which 43” fell between noon July 25th and noon July 26th. The NWS office sent a team to the Alvin area where they made a ‘bucket’ survey (measuring how much water had filled various containers, like empty oil drums, garbage cans, etc.) to compare to Mr. Davison’s measurements. Apparently the team came away convinced they were accurate and official enough to constitute a new national record for the U.S.

Results of the bucket survey made by the NWS team in July 1979 from the greater Houston, Texas area. A location in the suburb of Alvin reported 43” (1092 mm) over one 24-hour period during the storm. Map from ‘Weatherwise’ magazine August 1980 issue.

In any case, here for better or worse, is the most complete list of locations having reported 40” + 24-hour rainfalls that I can put together so far:

NOTE: The Cherrapunji figure of 49.07” on June 15-16, 1995 is derived from a two-day total of 2493 mm (98.15”) on June 15-16, 1995. The WMO is currently investigating this figure as a possible world record for a two-day measurement. What the maximum in 24 hours might have been has not yet been disclosed.

REFERENCES Most of the Chinese and Taiwan figures come from ‘Monsoons over China’ by Ding Yihui, Kluwer Academic Publishers, 1994. The Reunion rainfalls come from BAMS Dec. 1997, BAMS May 2009 and Monthly Weather Review Jan. 1950 ‘World’s Greatest Observed Point Rainfalls’ and MWR Feb. 1965 ‘Indian and Taiwan Rainfalls set New Records’ both articles by J.L.H. Paulhus. For the Alvin, Texas data see ‘Weatherwise’ magazine Aug. 1980 ‘An Apparent new Record for Extreme Rainfall’ by Jerry D. Hill. Japanese rainfall statistics from 'The Climate of Japan' by E. Fukui, Elsevier Publications, 1977.

Christopher C. Burt
Weather Historian

Precipitation Records Extreme Weather

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Chris -
I met Gary P. Nunn once, the fellow who wrote "London Home Sick Blues".
He lives at Marble Falls, Texas . I asked him if he was home when it rained 18 inches in 6 hours. He yes, his eyes got very big, and he said , "When that rain comes you better be on high ground".
I had a feeling, that Jamaica would have been on the list. Thanks Christopher!
The Bellenden Ker figure should be considered as an estimate only. In more detail:

1947 mm was reported in the 48 hours to 0900 5 January 1979. There was no observation at 0900 4 January 1979. (0900 is the standard daily rainfall measurement time in Australia).

960 mm was reported in the 24 hours ending at 1500 4 January 1979.

A 24-hour reading of 1140 mm has been quoted in some sources, including those used as the basis for the list above. This appears to have been derived by adding an 18-hour total for the period ending at 0900 on the 4th, estimated by temporal interpolation from the 960 mm figure above, to the measured 370 mm in the 6-hour period 0900-1500 on the 3rd. There is no real physical basis to this estimate (which is based on the implicit assumption that the rainfall rate was essentially constant through the 1500-1500 period) and I do not believe it can be given any standing.

The 48-hour reading implies that the 24-hour rainfall ending at 0900 must have been at least 973.5 mm on either the 4th or the 5th, which is in excess of the Australian daily record (907 mm at Crohamhurst in February 1893). However, it is possible that this was exceeded in 1999 (see below)

1870 mm was reported in the 48 hours to 0900 13 February 1999. This is less than the 1979 total, but it is possible that one of the 24-hour totals contained therein is higher than the highest 24-hour total from the 1979 event.

In essence, the conclusions from this are that the 1140 is an estimate, that the highest actually measured for an unrestricted 24-hour period was 960mm, and that the highest for a standard day ending at 0900 is 907mm (at Crohamhurst). The Crohamhurst figure is the figure recognised by the Bureau as the Australian daily record, which means we have the slightly bizarre situation that the two-day record is more than double the one-day record.

Personally, I think a reasonable estimate of the rainfall at Bellenden Ker on 4 January 1979 is around 1300mm, given that at other sites in the region about 2/3 of the two-day total for 4-5 January fell on the 4th. However, that can only be an estimate.

(It's an interesting site - it's at a TV tower on top of a ~1500m mountain which is accessed via a cable lift. Unsurprisingly, this means a lot of missed observations in extreme weather).

Those Japanese data is unverified and not in the JMA database, besides being completely different from data from nearby stations which recorded little or no rain on the same days.

There is almost no chance this data can be correct.

Anyway, the official record for the Reunion is the one which you placed in second place, with 1825mm.

The Cilaos record is contested and as for today, not official according to Meteo France.

The Amini Divi data is completely false , resulted on a wrong transmission, as for the last two which have been dismissed.

Also the Australia station should be taken out. There are MILLIONS of estimated figures allover the world which should be included than if we talk about "guess"and not measured numbers.

So that of China has never been minimally verified.
The list should be done brand new, since there are more wrong than correct data.

The Amin Divi data is unreliable.
There was a clear problem with the transmission of data which reported 1168mm and 16C of temperature (which is obviously IMPOSSIBLE) instead the 26C which was the temperature recorded few miles away in the nearby stoll of the Lakhadives which recorded 165.8mm on the same day.
The storm in '79 in SW Texas that gave Alvin, Texas 43", also got my apartment in Pasadena, TX, some water inside. Alvin is on very flat land, and it really got a Frog-Choker that day. Mr. K
I thought the definition of Bai-Yu (Chinese Mei-Yu.. called the "Plum rains") was a reliable period of heavy rains in early summer when the plums were well set. I am interested in this phenomenon but don't know much about it besides that it happens often enough to have gotten a name in both places.

Modification. I missed the July 25-26 date on first read of the post. THis is perhaps the tail end of the Bai-Yu season so Burt's sentence is valid. Other Mei-Yu and Bai-Yu comment is still solicited.

brings back memories of the 944 mm of rain we received here in Mumbai on 26th July 2005. Perhaps the highest any major city has ever received.
Quoting 8. Vebz25:
brings back memories of the 944 mm of rain we received here in Mumbai on 26th July 2005. Perhaps the highest any major city has ever received.

That ammount was recorded at the Santacruz Airport not at Mumbai downtown, which recorded a negligible ammount compared to the Airport.
Also, most of that ammount, was concentred in just baout 12 hours.
Technically it was not a deluge on a city , but on the area of its international airport.
The official record for Colaba Observatory in 24 hours is 575.6mm on 5 July 1974.
weatherhistorian has created a new entry.
See also the inventory of the most intense short-term rainfalls in the world on the website Géoclimat.org  !!!
This reminds me of the 620 mm recorded in Islamabad in July 2001 over a period of 12 hours. However, I have always wondered about the amount of rainfall recorded in a rain gauge near the hills which recorded 417 mm of rainfall on the same day but this amount excludes the most intense 6 hour period of the event during which this station has no data.
For comparison, Islamabad (Head office) recorded 532 mm during its most intense 6 hr period.
link: http://www.wmo.int/pages/prog/www/DPS/TC-DPFS-2002 /Papers-Posters/Topic3-NaeemShah.pdf