The heatmapTiles endpoint provides pollen-related heatmaps through tile overlay. A tile overlay is a collection of image tiles that can be displayed on top of Google Maps. Each image tile is 256 x 256 pixels.

The tile overlay is a grid assembled from a collection of tiles, each assigned (X,Y) coordinates. The tile with coordinates (0,0) is always at the northwest corner of the map. The X values increase from west to east, while the Y values increase from north to south.

The zoom level determines how large or small the contents of a map appear in a map view. The tile grid size is determined by scaling the X and Y coordinates exponentially by the zoom level.

gridSizeX = XzoomLevel
gridSizeY = YzoomLevel

For example, at a zoom level of 2, the world map is represented using a 4 x 4 matrix, for a total of 16 tiles.

The following image shows a TREE_UPI heatmap of the entire world, sectioned into tiles that can be accessed at a zoom level of 2.

A heatmap of the entire world as a 4 by 4 grid.

See Map and Tile coordinates for additional details.

You can request current pollen heatmap tiles using the heatmapTiles endpoint by sending an HTTP GET request to:


About the heatmap endpoint

All parameters listed below are required for a successful request:

  • KEY: Your application's API key. This key identifies your application for purposes of quota management. Learn how to get a key.
  • TYPE: The type of heatmap to return. See allowed values.
  • Z: Zoom level that determines how large or small the contents of a map appear in a map view. Allowed values are 0-16, where a value of 0 displays the entire world in a single tile.
  • X,Y: The tile coordinates relatively to the north east corner (0,0). X values increase from west to east and Y values increase from north to south. Coordinates must be valid for the specified zoom level. For example, if you set the zoom level to 2 and request a tile at coordinates (10,10), the API returns an error.

Example heatmap request

The image above shows a TREE_UPI heatmap with a zoom level of 2, along with the coordinates of each tile. The following example uses the heatmapTiles endpoint to request the tile at coordinates (2,1):


The tile appears as an image that can be overlaid on a map:

An example of a heatmap tile using the TREE_UPI map.

For more information on overlaying tiles on top of the default map, see Overlay Map Types.