Based on 5 years of measurements of integrated water vapor (IWV), surface mixing ratio (MR), and rain rate, we investigate the relationship between the water vapor field evolution and the precipitation lifecycle. We show that in 76% of the cases the IWV reaches a maximum before the peak of precipitation, with the precipitation peak occurring on average 20 min after the IWV maximum. This delay can be related to the fall time of the precipitation. We also show that the moister the atmosphere, the greater the precipitation rates and the longer the delay. Unlike the IWV, the MR reaches a maximum after the precipitation peak in 60% of the cases, highlighting the interest of IWV compared to surface MR only. This paper and the discussions within it open a pathway to complementary studies and applications for heavy precipitation prediction.