The name of Namtok Chet Sao Noi is from the story of the people in the area. For along time, seven ladies tourist drowned together in this waterfall. (Namtok=waterfall, Chet=seven, Sao Noi=young lady) and another story believed that it came from a village’s name “Ban Sao Noi” (Pronounce shortly) and it became “Ban Sao Noi” until present.
On September 5, 1978 (B.E.2521) Nakhon Ratchasima Regional Forestry Office surveyed the area around Namtok Chet Sao Noi for setting to be a forest park with the area 0.72 sq.km, moreover supplemented surveying an area of Dong Phaya Yen National Reserved Forest about 0.78 sq.km, so including the total area 1.50 sq.km approximately.
The Royal forest department surveyed Muak Lek stream, which born from Khao Yai forest, Pak Chong district, Nakhon Ratchasima province, confluence with Pasak river at Wang Muang sub-district, Muak Lek district, Sara Buri province, due to it is the waterway flowing through the upper part of the plateau at Sara Buri province pass the complex not rather heigh mountain range so it caused of short level waterfalls, but the beautiful of the nature is different, it seems to be a man- made dam with stream all round year.
So the Royal forest department declared to be Namtok Chet Sao Noi Forest Park on May 21, 1980, cover the area of Muak Lek, Pak Chong sub-district and in the Dong Phaya Yen and Thap Kwang-Muak Lek National Reserved Forests with the area about 0.86 sq.km.
Afterwards Dr.Plodprasop Surasawadi who is the head of the Royal forest department visited Namtok Chet Sao Noi forest park on June 2002, then he saw the development of forest park, composed with the amount of the tourists were increasing and a lot so he had a policy that should be expanded the area for carrying the tourists, also increased surveying with the research in the ecological data and the foundation data on the general management, all those for the evaluation of possibility to determine the area and planing to be a national park.
National Park office considered and approved to determine this area to be a national park with approximately area 28.06 sq.km. And the order number 2177/2546 on November 10, 2003 to Mr.Sompong Kornthong, the head of Namtok Chet Sao Noi forest park had the duty to control and manage this area after became the national park.
The most area of Namtok Chet Sao Noi National Park is ruggedly mountainous alternate with the plateau. The area rather dry with the shallow soil surface, height above msl is 180-402 m. The highest peak of the area is on the Chokchai Phatthana with 402 m above msl , next is the mountain range which is in the central of the area and Ban Dong Namcha mountain range 386, 359 m above msl following. The foothills are on the East and the North side, which near Khlong Muak Lek, there is a stream flows all year and tributary to Pasak river at Wang Muang district while the central area with streamlet flow through is Huai Laeng which has the stream in only rainy season.
The climate predicted from the data of rain found the area of the national park in Central of Thailand is on the influent of monsoon, on May-October has the influent of Southwest monsoon wind, induced humidity from the sea and the ocean and the caused of rainy season. On November-February has the influent of Northeast monsoon wind, lead the coldness from the North of Asia, bring to the winter. Whereas the summer is in February-April.
A data of rain in the period of 10 year (B.E.2536-2545) measures the average of rain amount all year about 1,191 ml. August is the month with the highest peak of rain amount on day period about 46 ml. September has the most of average rain amount about 232 ml.
A temperature data in the period of 10 year (B.E.2536-2545), the average temperature all year about 26 degree Celsius, maximum average temperature is 31 degree Celsius and minimum is 21 degree Celsius, dropping to 17 degree Celsius in January and soaring to 34 degree Celsius in April.