Beginning around June each year, the rainy season starts. It ends by the time December comes around. But it rains every month on Guam, and it can rain in the dry season and we can go for days with no rain in the rainy season.
A rainy July means : bring your umbrella at every Liberation Day parade.
The fiestas of Agat (all three of them), Barrigada, Talofofo, Mangilao, Yoña, Umatac and a few others can all get drenched because they occur during Fanuchånan. Sometimes the lukao (procession) is cancelled.
Fanuchånan comes from FAN + UCHÅN + AN. Fan+word+an = place of, or time of.
AVERAGE MONTHLY RAINFALL ON GUAM
Source : http://ns.gov.gu/climate.html
The year 2004 was one of our wettest. That year, June had 38 inches of rain, and August had 37.3 inches. Fotgon!