June 17

Alerts Endpoint: New European Alerts and Polygon Support

It’s been a busy few weeks with the public beta of the new conditions endpoint, improvements to the forecast API, and recent enhancements to the global radar map layer. We’re continuing this trend with significant upgrades to our alerts endpoint by adding support for European alerts and alert polygons!

European Alerts

Alerts across Europe are now part of our alerts API. We have integrated weather warnings from Meteoalarm into the API and they are now available for all AerisWeather API users. European alerts will also be added to the alerts layer within the AerisWeather Mapping Platform in the coming weeks.

Accessing the new European alerts is as simple as querying the alerts endpoint for European locations:

Query by City, Country

Return active alerts for Paris, France:

Or use the two-letter country abbreviation:

Query by Latitude/Longitude

Queries can be made using latitude, longitude, which is perfect for mobile users:

Alerts are now available for the following countries:

Austria - ATFrance - FRLuxembourg - LUSerbia - RS
Belgium - BEGermany - DEMalta - MTSlovakia - SK
Bosnia - BAGreece - GRMoldova - MDSlovenia - SI
Canada - CAHungary - HUMontenegro - MESpain - ES
Croatia - HRIceland - ISNetherlands - NLSweden - SE
Cyprus - CYIreland - IENorway - NOSwitzerland - CH
Czechia - CZIsrael - ILPoland - PLUnited Kingdom - UK
Denmark - DKItaly - ITPortugal - PTUnited States - US
Estonia - EELatvia - LVRepublic of North Macedonia - MK
Finland - FILithuania - LTRomania - RO

Differences between EU & US / Canada Alerts

Within the United States and Canada, alerts are disseminated as warnings, watches, advisories, and statements. Per the NWS, these are described as follows:

  • Warning – A warning is issued when hazardous weather or hydrologic event is occurring, imminent or likely. A warning means weather conditions pose a threat to life or property. People in the path of the storm need to take protective action.
  • Advisory – An advisory is issued when hazardous weather or hydrologic event is occurring, imminent, or likely. Advisories are for less serious conditions than warnings, that cause significant inconvenience, and if caution is not exercised, could lead to situations that may threaten life or property.
  • Watch – A watch is when the risk of hazardous weather or hydrologic event has increased significantly, but its occurrence, location, or timing is still uncertain. It is intended to provide enough lead time, so those who need to set their plans in motion can do so. A watch means that hazardous weather is possible. People should have a plan of action in case a storm threatens, and they should listen for later information and possible warnings, especially when planning travel or outdoor activities.

However, European alerts are all issued as weather warnings with different severity levels: moderate, severe, and extreme/critical. According to MeteoAlarm:

  • Moderate: The weather is potentially dangerous. The weather phenomena that have been forecast are not unusual, but be attentive if you intend to practice activities exposed to meteorological risks. Keep informed about the expected meteorological conditions and do not take any avoidable risk.
  • Severe: The weather is dangerous. Unusual meteorological phenomena have been forecast. Damage and casualties are likely to happen. Be very vigilant and keep regularly informed about the detailed expected meteorological conditions. Be aware of the risks that might be unavoidable. Follow any advice given by your authorities.
  • Extreme: The weather is very dangerous. Exceptionally intense meteorological phenomena have been forecast. Major damage and accidents are likely, in many cases, with a threat to life and limb, over a wide area. Keep frequently informed about detailed expected meteorological conditions and risks. Follow orders and any advice given by your authorities under all circumstances, be prepared for extraordinary measures.

New alert type codes are utilized for the European Alerts due to the differences in how European alerts are issued. These new alert codes are similar to:

, which stands for Moderate Thunderstorms.

The complete list of weather alert types and their associated codes are available within our alert types documentation.

Again, the European alerts are available for all AerisWeather API users!

Alert Polygons

An often requested feature has been the ability to return the polygon(s) for an alert via the alerts API output. This functionality is now available for the US, Canada, and Europe!

For example, to have the alerts API return the alert polygons, use the   query parameter.

The above will return any alerts for Minneapolis, MN, along with their associated polygons. The returned polygons will be a GeoJSON object, of either a polygon or a multi-polygon within the  attribute of the alerts API output.

To have the entire API result returned as GeoJson add the  parameter:

Alert Polygons within the United States

Alerts within Europe are issued for zones as defined by MeteoAlarm. Within Canada, warnings are issued for Canadian Location Codes (CLCs), as issued by Environment Canada. Within the US, alerts are issued for weather zones, counties/parishes (AKA FIPs), and fire zones.

Additionally, some US alerts contain small polygons rather than entire counties or zones. These are included when only a portion of the county or weather zone will be affected. They are most commonly included with short-fuse warnings, such as severe thunderstorm and tornado warnings. The alerts API will continue to return the small polygon with US alerts when applicable even without the  parameter.

When using , the alerts API will return the small polygon when available. Otherwise, it will return the polygon(s) for the corresponding county, weather zone, or fire zone the alert is issued for.

The new enhanced polygon support is available for AerisWeather Premium users.

Polygons and Bandwidth

The size of the API response and bandwidth may significantly increase when requesting polygons within the alerts API output. In the US, the API response may be several hundred times in size, especially along coastlines and mountainous areas where polygons contain considerably more line segments and vertices. Due to the significant increase in API response size when requesting polygons, the API will limit the response to a maximum of 50 alerts per API query.

Alerts via Observation Station IDs

Another common request is for the ability to query alerts by an observation station ID, such as an Airport Code, ICAO, or even a Personal Weather Station ID. With this update, the alerts API now supports this capability.

To query alerts for the Minneapolis-St Paul International Airport (KMSP)

Or to query by PWSweather station ID:

Furthermore, this improvement means you can query alerts by any of our supported place formats!

Start Integrating our Alerts API Today!

We have made some significant upgrades to the Alerts API, with European alerts and improved querying capabilities for all AerisWeather API users. Alert polygon support available for AerisWeather API Premium users. Not currently a user? Then check out our free developer trial.

Check out the improved alerts and tell us how you are using it!


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