A flood watch is in effect for much of New Hampshire with the forecast calling for heavy rainfall and a chance of persistent thunderstorms. A watch means conditions are favorable for flooding, while a warning means flooding is imminent or already occurring. National Weather Service A map showing rainfall forecast for New Hampshire through Thursday, July 30, 2026. Excessive rain runoff may result in flooding of rivers, creeks, streams and other low-lying areas that are prone to flooding. Thunderstorms are possible after 2 p.m. for central New Hampshire, with wind gusts as high as 20 mph.