Siyam-siyam or (literally nine-nine) is a term used for the annual prolonged rains brought about by the southwest monsoon or habagat weather system in the western parts of the Philippines during the months of May to September.<ref name = "ref1">Graciano P. Yumul Jr; Susan R. Espinueva. Unconventional dry spell. Inquirer.net - Opinion, August 5, 2007. Accessed on May 28, 2008.</ref> The siyam-siyam is said to have arrived when everything in the environment looks gray and misty, and the rain pours intermittently several times a day.<ref>Ely Oyzon. Philippines Vacation 2007 Chapter 16. Ely's Insight and Reflection, December 15, 2007. Accessed on May 29, 2008.</ref>
It is believed that the prolonged rains brought about by the habagat pours continuously for nine days and nine nights, hence the term Nine-nine, translated in Filipino as Siyam-siyam.<ref>Editorial. Monsoon Tourism. The Manila Times Internet Edition - OPINION, August 19, 2007. Accessed on May 29, 2008.</ref> A popular expression in the Philippine vernacular is "baka abutin ng siyam-siyam", used when something is taking too much time to finish, that it might take months until the siyam-siyam arrives.
Climate change has drastically affected the weather in the Philippines, even causing the delay of the arrival of the siyam-siyam in July 2007.<ref name = "ref1">Graciano P. Yumul Jr; Susan R. Espinueva. Unconventional dry spell. Inquirer.net - Opinion, August 5, 2007. Accessed on May 28, 2008.</ref> In the 2006 Germanwatch Climate Risk Index, the Philippines topped the list of the countries most affected by extreme weather events and climate change.<ref>Sven Harmeling, Global Climate Risk Index 2008 (PDF File, Full-text). Germanwatch:December 2007. ISBN 978-3-939846-21-5. Accessed on May 29, 2008.</ref>