The IEM maintains an ever growing archive of automated airport weather observations from around the world! These observations are typically called 'ASOS' or sometimes 'AWOS' sensors. A more generic term may be METAR data, which is a term that describes the format the data is transmitted as. If you don't get data for a request, please feel free to contact us for help. The IEM also has a one minute interval dataset for Iowa ASOS (2000-) and AWOS (1995-2011) sites. This archive simply provides the as-is collection of historical observations, very little quality control is done. "M" is used to denote missing data.

Here is a python script example that automates the download of data from this interface. A community user has contributed R language version of the python script.

Please be patient with this page as it will take a number of seconds to process your request and provide the result.

Select Network

1) Select Station/Network by clicking on location:

2) Select From Available Data:

Note: Cloud information and raw METAR data is not available for all observations, the IEM continues to backfill this information.

3) Specific Date Range (If needed):

Note: There is up to an hour delay for observations to appear within this service. A process runs at approximately 20 minutes after the hour to copy over the previous hour's worth of data in the backend database behind this service.

Start Date:
End Date:

4) Timezone of Observation Times:

The following options are available for how the observation time is presented.

5) Download Options:

Data Format:

Include Latitude + Longitude?

6) Limit Report Types

New! This attempts to filter the downloaded data to only include those reports you want. In the future, this will deliniate between routine and special obs. Select the report types to include.

7) Finally, get Data:

Download Variable Description
ASOS User's Guide has detailed information about these data variables. The value "M" represents either value that was reported as missing or a value that was set to missing after meeting some general quality control check, or a value that was never reported by the sensor. The METAR format makes it difficult to determine which of the three cases may have happened.

three or four character site identifier
timestamp of the observation
Air Temperature in Fahrenheit, typically @ 2 meters
Dew Point Temperature in Fahrenheit, typically @ 2 meters
Relative Humidity in %
Wind Direction in degrees from north
Wind Speed in knots
One hour precipitation for the period from the observation time to the time of the previous hourly precipitation reset. This varies slightly by site. Values are in inches. This value may or may not contain frozen precipitation melted by some device on the sensor or estimated by some other means. Unfortunately, we do not know of an authoritative database denoting which station has which sensor.
Pressure altimeter in inches
Sea Level Pressure in millibar
Visibility in miles
Wind Gust in knots
Sky Level 1 Coverage
Sky Level 2 Coverage
Sky Level 3 Coverage
Sky Level 4 Coverage
Sky Level 1 Altitude in feet
Sky Level 2 Altitude in feet
Sky Level 3 Altitude in feet
Sky Level 4 Altitude in feet
Present Weather Codes (space seperated)
unprocessed reported observation in METAR format