For those of you who would like to know the low or high temperature or the rainfall history during the previous 24 hour period, you should click on the TABLE button for the gauge in your area. For example if one clicks on TABLE for the Iowa River near Iowa City (Burlington street bridge) you will see columns labeled with the date and time (columns 3 and 4) and columns labeled /PC (precipitation) or /TA (temperature).
Note that most, but not all stations measure rainfall.