The answer would be that when it is near the nearest climate and it could also be when there is a heavey storm coming it's way
10 inches of rainfall
In the eyewall
The heaviest recorded daily rainfall total in UK was at Upwey and Martinstown in Dorset when 279 mm was recorded on 18 July 1955.
The Northeast Facing Hills
Kenya has the heaviest rainfall between approximately March and May, but rainfall is also received notably from October to December. The heaviest rain varies, but may occur at any time of the year as weather is highly unpredictable.
The rain is heaviest in a hurricane near the center of the storm, which is called the eye wall. The eye wall is where the strongest winds and most intense rainfall occur, with rainfall rates reaching several inches per hour.
the time between the heaviest rainfall and the peak discharge
The heaviest rainfall per year is typically found in Mawsynram, a village in the northeastern state of Meghalaya in India. Mawsynram receives an average annual rainfall of around 467.4 inches (11,871 millimeters), making it one of the wettest places on Earth.
The heaviest rainfall in Africa typically occurs in regions near the equator, such as the Congo Basin and parts of West Africa. These areas receive high levels of precipitation due to their proximity to the Intertropical Convergence Zone, which is a belt of low pressure where warm, moist air rises and produces heavy rainfall.
Cherrapunji, located in northeastern India, receives the heaviest rainfall primarily due to its geographical position and the influence of the monsoon winds. It is situated on the windward side of the Khasi Hills, where moisture-laden winds from the Bay of Bengal are forced to rise, leading to intense orographic rainfall. The combination of high elevation and the convergence of various weather patterns contributes to its extraordinary annual rainfall totals.
The heaviest rainfall in Canada occurs along the BC coast, where annual precipitation can sometimes exceed 2500 mm. Ocean Falls, BC, has the greatest annual rainfall of 4145.1 mm
The average rainfall in El Salvador is 72 inches. The heaviest rain will fall in the coastal plain and the wet season begins from May to October.