Almost any time of the year is good to visit Ninh Binh. Like in all the north Vietnam, May to October in Ninh Binh is hot, humid and with high rainfall.
The region can be especially vulnerable to typhoons during September. November to April months tend to be cooler and dry. However, the rainy season is also when the rice fields are at their best vivid green, so there’s really a reason to visit all year round!