The hydronet system began collecting 15-minute rainfall data in July 1994. Currently the data is collected from 70 gages located throughout the Hawaiian islands. The data is stored by month, in comma delimited text files so that they can be easily imported into a spreadsheet. Data is available in both Hawaii Standard Time (HST) as well as in Coordinated Universal Time (UTC). The dataset is updated monthly. The data has not been quality controlled, and therefore is not certified by the National Weather Service. Please see the disclaimer for further details.
Notes on the dataset:
Each file is a *.zip file which contains the data for every hydronet rain gage in that particular month. Software to unzip these files can be downloaded from InfoZip. When the first file is unzipped, it will create one directory for each rain gage. If the data is from April 1998 or later, there will be 70 directories created. For any data previous to this date, 68 directories will be created. In each directory that is created, you will find a single file with the data for that specific rain gage, for whatever month you chose. If more monthly files are downloaded and unzipped, the individual gage files will be placed into their respective directories (i.e. directories will only be created the first time). For example, if you downloaded six months worth of data (six *.zip files) and unzipped them on your computer, you should end up with at least 68 directories, each containing six files.
Each file is a comma delimited text file which should contain 96 rows, while the number of columns correspond to the amount of days there are in a particular month, so the first column is the 1st day of the month, the second column is the 2nd day, etc. The first row is the gage reading for 0000 of that particular day, the second row is the 0015 reading, the third row is the 0030 reading, etc., thru the last row, which is the reading for 2345 of that day. Because the gages use tipping bucket counters, the numbers given are running totals in inches (see "cautions:" below). If a reading was not taken while the gage is active, only a period will appear in the "cell" of the spreadsheet. During periods when the gage is inactive (broken), or data is simply missing due to any number of reasons, m's will appear in the cells.
For each dataset (HST and UTC data), the directories will be named HI02 for gage 02, HI03 for gage 03, up to gage 99 (HI99). Not all numbers from 2 thru 99 are represented. For the HST dataset, the individual files will be named in the following fashion; 2 or 3 character gage number, 4 character year, period, and then 3 character month. For example, a file named 451996.Feb means the file contains the data for gage 45, for February 1996, in HST. The UTC file names follow the same convention except that the months are given numerically, i.e 01 for January, 02 for February, etc. For example, the file named 451996.02means the file contains the data for gage 45, for February, in UTC.
- Because the readings are running totals, you have to sutract successive cells to get the rainfall amount for a particular 15-minute period. Accordingly, to get a 24 hour total, you have to subtract the first reading of that day from the first reading of the following day.
- The individual gage counters go up to 99.99 (inches) and then automatically reset to 00.00 . In addition to these automatic resets, individual counters will be manually reset if any work or maintenance is performed on that particular gage, regardless of the reading at that time.