Engineering 101: Precipitation

A few months ago, I posted about the Rainfall Intensity and some of the information you will need to generate an intensity-duration-frequency curve.  I want to provide a little more rainfall data, including some links to precipitation data.

I referenced the FHWA HEC-12 Document that walks you through both Eastern and Western calculations using HYDRO35 and NOAA Atlas 2.

Since I am in Illinois, we tend to use the rainfall data established by the Illinois State Water Survey.

Rainfall Frequency Atlas of the Midwest

Huff, Floyd A., and James R. Angel, 1992 ISWS B-71 NTIS#: PB93-164606

Frequency Distributions and Hydroclimatic Characteristics of Heavy Rainstorms in Illinois
Huff, Floyd A., and James R. Angel, 1989 ISWS B-70 NTIS#: PB89-203988

Time Distributions of Heavy Rainstorms in Illinois
Huff, Floyd A., 1990 ISWS C-173 NTIS#: PB90-253253

This is where the Huff Distribution found in the Hydraflow Precipitation Distributions for use in the SCS methods. 


Neighboring Indiana has a great site for their rainfall data – “Rainfall Frequency for Indiana

I would love to add your rainfall data.


MCA:  Fixed the Rainfall Link for Indiana


  1. Tony Kinder says:

    While I am a Tennessee engineer, the site I prefer for Tennessee (and I would have thought for several other states as well) would be the Hydrometeorological Design Studies Center – Precipitation Frequency Data Server (PFDS). It may be found at:
    It is an outstanding site that I would strongly recommend. I would be curious about other people’s thoughts about this site.

  2. Matt Keiser says:


    Please check your link for the Indiana rainfalls. Its broken and a 404 error from DNR is shown.

    Matt Keiser

  3. Matt – Thanks – I fixed the post to point here: