Question: When was the most rainfall for the city where the State Fair of Oklahoma is held?

full_context: Document 1: Oklahoma City: The city is roughly bisected by the North Canadian River (recently renamed the Oklahoma River inside city limits). The North Canadian once had sufficient flow to flood every year, wreaking destruction on surrounding areas, including the central business district and the original Oklahoma City Zoo. In the 1940s, a dam was built on the river to manage the flood control and reduced its level. In the 1990s, as part of the citywide revitalization project known as MAPS, the city built a series of low-water dams, returning water to the portion of the river flowing near downtown. The city has three large lakes: Lake Hefner and Lake Overholser, in the northwestern quarter of the city; and the largest, Lake Stanley Draper, in the sparsely populated far southeast portion of the city.
Document 2: Oklahoma City: Other major sporting events include Thoroughbred and Quarter horse racing circuits at Remington Park and numerous horse shows and equine events that take place at the state fairgrounds each year. There are numerous golf courses and country clubs spread around the city.
Document 3: State Fair of Texas: The State Fair of Texas is an annual state fair held in Dallas at historic Fair Park. The fair has taken place every year since 1886 except for varying periods during World War I and World War II. It usually begins the last Friday in September and ends 24 days later. While the State Fair of Texas considers quantifying its official attendance figures ``too much of a hassle '', it is still consistently recognized as one of the most highly attended and best state fairs in America as well as Dallas's signature event.
Document 4: Oklahoma: Because of Oklahoma's position between zones of differing prevailing temperature and winds, weather patterns within the state can vary widely over relatively short distances and can change drastically in a short time. As an example, on November 11, 1911, the temperature at Oklahoma City reached 83 °F (28 °C) in the afternoon (the record high for that date), then an Arctic cold front of unprecedented intensity slammed across the state, causing the temperature to crash 66 degrees, down to 17 °F (−8 °C) at midnight (the record low for that date); thus, both the record high and record low for November 11 were set on the same date. This type of phenomenon is also responsible for many of the tornadoes in the area, such as the 1912 Oklahoma tornado outbreak, when a warm front traveled along a stalled cold front, resulting in an average of about one tornado per hour over the course of a day.
Document 5: Oklahoma: During a 10-day run in Oklahoma City, the State Fair of Oklahoma attracts roughly one million people along with the annual Festival of the Arts. Large national pow-wows, various Latin and Asian heritage festivals, and cultural festivals such as the Juneteenth celebrations are held in Oklahoma City each year. The Tulsa State Fair attracts over one million people during its 10-day run, and the city's Mayfest festival entertained more than 375,000 people in four days during 2007. In 2006, Tulsa's Oktoberfest was named one of the top 10 in the world by USA Today and one of the top German food festivals in the nation by Bon Appetit magazine.
Document 6: Oklahoma City: Oklahoma City has a very active severe weather season from March through June, especially during April and May. Being in the center of what is colloquially referred to as Tornado Alley, it is prone to especially frequent and severe tornadoes, as well as very severe hailstorms and occasional derechoes. Tornadoes have occurred in every month of the year and a secondary smaller peak also occurs during autumn, especially October. The Oklahoma City metropolitan area is one of the most tornado-prone major cities in the world, with about 150 tornadoes striking within the city limits since 1890. Since the time weather records have been kept, Oklahoma City has been struck by thirteen violent tornadoes, eleven F/EF4s and two F/EF5. On May 3, 1999 parts of southern Oklahoma City and nearby suburban communities suffered from one of the most powerful tornadoes on record, an F5 on the Fujita scale, with wind speeds estimated by radar at 318 mph (510 km/h). On May 20, 2013, far southwest Oklahoma City, along with Newcastle and Moore, was hit again by a EF5 tornado; it was 0.5 to 1.3 miles (0.80 to 2.09 km) wide and killed 23 people. Less than two weeks later, on May 31, another outbreak affected the Oklahoma City area, including an EF1 and an EF0 within the city and a tornado several miles west of the city that was 2.6 miles (4.2 km) in width, the widest tornado ever recorded.
Document 7: Oklahoma: Norman plays host to the Norman Music Festival, a festival that highlights native Oklahoma bands and musicians. Norman is also host to the Medieval Fair of Norman, which has been held annually since 1976 and was Oklahoma's first medieval fair. The Fair was held first on the south oval of the University of Oklahoma campus and in the third year moved to the Duck Pond in Norman until the Fair became too big and moved to Reaves Park in 2003. The Medieval Fair of Norman is Oklahoma's "largest weekend event and the third largest event in Oklahoma, and was selected by Events Media Network as one of the top 100 events in the nation".
Document 8: Oklahoma: Oklahoma's centennial celebration was named the top event in the United States for 2007 by the American Bus Association, and consisted of multiple celebrations saving with the 100th anniversary of statehood on November 16, 2007. Annual ethnic festivals and events take place throughout the state such as Native American powwows and ceremonial events, and include festivals (as examples) in Scottish, Irish, German, Italian, Vietnamese, Chinese, Czech, Jewish, Arab, Mexican and African-American communities depicting cultural heritage or traditions.
Document 9: Oklahoma City: Oklahoma City is on the I-35 Corridor and is one of the primary travel corridors into neighboring Texas and Mexico. Located in the Frontier Country region of the state, the city's northeast section lies in an ecological region known as the Cross Timbers. The city was founded during the Land Run of 1889, and grew to a population of over 10,000 within hours of its founding. The city was the scene of the April 19, 1995 bombing of the Alfred P. Murrah Federal Building, in which 168 people died. It was the deadliest terror attack in the history of the United States until the attacks of September 11, 2001, and remains the deadliest act of domestic terrorism in U.S. history.
Document 10: Seattle: Among Seattle's prominent annual fairs and festivals are the 24-day Seattle International Film Festival, Northwest Folklife over the Memorial Day weekend, numerous Seafair events throughout July and August (ranging from a Bon Odori celebration to the Seafair Cup hydroplane races), the Bite of Seattle, one of the largest Gay Pride festivals in the United States, and the art and music festival Bumbershoot, which programs music as well as other art and entertainment over the Labor Day weekend. All are typically attended by 100,000 people annually, as are the Seattle Hempfest and two separate Independence Day celebrations.
Document 11: United Kingdom weather records: Duration Level Location Date Highest 5 - min total Approx. 32 mm Preston, Lancashire 10 August 1893 Highest 30 - min total 80 mm Eskdalemuir, Dumfries and Galloway 26 June 1953 Highest 60 - min total 92 mm Maidenhead, Berkshire 12 July 1901 Highest 90 - min total 117 mm Dunsop Valley, Lancashire 8 August 1967 Highest 120 - min total 155 mm Hewenden Reservoir, West Yorkshire 11 June 1956 Highest 155 - min total 169 mm Hampstead, London 14 August 1975 Highest 180 - min total 178 mm Horncastle, Lincolnshire 7 October 1960 Highest 24 - hour total (1800 - 1800) 341.4 mm Honister Pass, Cumbria 5 December 2015 Highest 24 - hour total (0900 - 0900) 279 mm Martinstown, Dorset 18 July 1955 Highest 48 - hour total (0900 - 0900) 405 mm Thirlmere, Cumbria 4 to 5 December 2015 Highest 72 - hour total (0900 - 0900) 456.4 mm Seathwaite, Cumbria 17 to 19 November 2009 Highest 96 - hour total (0900 - 0900) 495 mm Seathwaite, Cumbria 16 to 19 November 2009 Highest Monthly Total 1396.4 mm Crib Goch, Snowdon 1 to 31 December 2015
Document 12: Oklahoma: Oklahoma had 598 incorporated places in 2010, including four cities over 100,000 in population and 43 over 10,000. Two of the fifty largest cities in the United States are located in Oklahoma, Oklahoma City and Tulsa, and 65 percent of Oklahomans live within their metropolitan areas, or spheres of economic and social influence defined by the United States Census Bureau as a metropolitan statistical area. Oklahoma City, the state's capital and largest city, had the largest metropolitan area in the state in 2010, with 1,252,987 people, and the metropolitan area of Tulsa had 937,478 residents. Between 2000 and 2010, the cities that led the state in population growth were Blanchard (172.4%), Elgin (78.2%), Jenks (77.0%), Piedmont (56.7%), Bixby (56.6%), and Owasso (56.3%).
Document 13: Houston: Many annual events celebrate the diverse cultures of Houston. The largest and longest running is the annual Houston Livestock Show and Rodeo, held over 20 days from early to late March, is the largest annual livestock show and rodeo in the world. Another large celebration is the annual night-time Houston Pride Parade, held at the end of June. Other annual events include the Houston Greek Festival, Art Car Parade, the Houston Auto Show, the Houston International Festival, and the Bayou City Art Festival, which is considered to be one of the top five art festivals in the United States.
Document 14: Oklahoma: All of the state frequently experiences temperatures above 100 °F (38 °C) or below 0 °F (−18 °C), though below-zero temperatures are rare in south-central and southeastern Oklahoma. Snowfall ranges from an average of less than 4 inches (10 cm) in the south to just over 20 inches (51 cm) on the border of Colorado in the panhandle. The state is home to the Storm Prediction Center, the National Severe Storms Laboratory, and the Warning Decision Training Branch, all part of the National Weather Service and located in Norman. Oklahoma's highest recorded temperature of 120 °F (49 °C) was recorded at Tipton on June 27, 1994 and the lowest recorded temperature of −31 °F (−35 °C) was recorded at Nowata on February 10, 2011.
Document 15: Oklahoma City: With 19.48 inches of rainfall, May 2015 was by far Oklahoma City's record-wettest month since record keeping began in 1890. Across Oklahoma and Texas generally, there was record flooding in the latter part of the month
ground_truth: May 2015
sub_queries: Where is the State Fair of Oklahoma? Answer: Oklahoma City
When was the most rainfall for Oklahoma City ? Answer: May 2015