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Documentation for /json/spcoutlook.py
This service provides access to the Storm Prediction Center's Convective Outlook products. This service is a nasty bit of confusion for the three or four different modes that it can be run in. Those modes being:
- Provide the current day X outlook for a given point (current=1 param).
- Provide all day X outlooks for a given point.
- Provide the day X outlook for a given point and given valid time (time param).
- Provide the most recent X number of outlooks for each threshold level for a given lat/lon point (last param).
There are examples below or feel free to yell at daryl for big a mess this is.
Changelog
- 2026-03-22: Add a new field to the JSON response called conditional, which will indicate the CIG1-3 or legacy SIGN for current queries.
- 2026-03-06: Sadly, the recently changed time parameter handling created additional service ambiguity. There is now an additional boolean parameter called current, which when enabled causes the service to ignore the time parameter and instead return the current outlook for the given day.
- 2026-03-03: The ill conceived support for time being now or current was removed.
- 2026-02-26: Renamed top level metadata generation_time to generated_at for better consistency across IEM services.
Example Usage
Get all the day 1 outlooks for Pierre, South Dakota. First in JSON, then CSV, and finally Excel.
https://mesonet.agron.iastate.edu/json/spcoutlook.py?lat=44.368&lon=-100.336&day=1 https://mesonet.agron.iastate.edu/json/spcoutlook.py?lat=44.368&lon=-100.336&day=1&fmt=csv https://mesonet.agron.iastate.edu/json/spcoutlook.py?lat=44.368&lon=-100.336&day=1&fmt=excel
Provide the day 1 outlook for Pierre, SD valid at 8 UTC on 3 Aug 2024
Provide the most recent outlook for each categorical threshold for day 2 for Washington, DC
https://mesonet.agron.iastate.edu/json/spcoutlook.py?lat=38.907&lon=-77.037&day=2&last=1
Return the last outlook of each threshold for day 4 for Washington, DC
Provide the current day 2 outlook for Washington, DC
https://mesonet.agron.iastate.edu/json/spcoutlook.py?lat=38.907&lon=-77.037&day=2¤t=1
Provide the day 2 outlook that was valid at 20 UTC on 6 March 2026. This is returning the day 2 forecast made on 5 March 2026.
CGI Arguments
The following table lists the CGI arguments that are accepted by this service. A HTTP GET request is required. Fields of type Multi-Params or CSV value can accept either a comma separated list or multiple parameter and value combinations. For example, ?foo=1&foo=2 is equivalent to ?foo=1,2.
| Field | Type | Description |
|---|---|---|
| callback | string or null | Legacy JSON-P style callback. It is likely best to not depend on this usage. The IEM website has a permissive CORS. |
| current | boolean | Return the currently valid outlook for the given day and category. The time parameter is ignored when this is enabled. |
| fmt | string | The format to return data in, either json, excel, or csv |
| lat | number | Latitude (decimal degrees) of point of interest |
| lon | number | Longitude (decimal degrees) of point of interest |
| last | integer | Limit to last N outlooks, 0 for all |
| day | integer | Day to query for, 1-8 |
| time | string or null | Optional specification for a valid timestamp to query outlooks for. |
| cat | string | A label for the category of the outlook type. Valid values are: ANY SEVERE, CATEGORICAL, CRITICAL FIRE WEATHER AREA, DRY THUNDERSTORM CRITICAL FIRE WEATHER AREA, FIRE WEATHER CATEGORICAL, HAIL, TORNADO, WIND |