USA NPN National Phenology Network

Taking the Pulse of Our Planet

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Image of grass, mostly green, showing flowers.

Red brome transforms native ecosystems and rangelands across the western US.

Image credit:
Scott Goetz

Red Brome Forecast

Red brome is an invasive grass that negatively impacts rangelands and native desert plant and animal communities in the western US. This annual grass increases fire risk and intensity in ecosystems that are not adapted to fire. 

Red brome flowering six day forecast

Red Brome Flowering 6-day Forecast

Red Brome Senescence 6-day Forecast

Red Brome Senescence 6-day Forecast

Pheno Forecast maps predict key life cycle stages in invasive and pest species, to improve management efficacy. The red brome Pheno Forecast is based on growing degree day and daylength thresholds for triggering flowering and senescence. (Senescence refers to the end of the annual cycle when the grass is no longer green.) These maps are updated daily and available 6 days in the future.

Help us improve these maps! Our Pheno Forecast map products are in development, and we seek input on their performance in your area. Visit our brome reporting page and let us know when you see flowering and senescence. We also welcome your feedback on the maps; you can share thoughts on the right sidebar of this page. 

Species Background

Red brome (Bromus rubens) was introduced from the Mediterranean region to the western US in 1880. The presence of red brome dramatically alters ecosystems, degrades rangelands and increases fire risk. 

Forecast Details

Field of red brome (grass) with ripe seedheads

We forecast flowering and senescence in red brome based on growing degree days and daylength. The forecasts can support ranchers in timing grazing after grasses have grown enough to provide good forage, but prior to unpalatable flowering and seeding stages. This practice reduces the development of new seeds and subsequent spread of the species. The forecasts also support the interpretation of satellite imagery of grassland green up.


GDD threshold*

Base temp

Start date

GDD method

Model origin





Dec 1

Simple average


Prevéy et al. in prep




Jan 1

Simple average


Prevéy et al, in prep

*The accumulations in this model are adjusted based on daylength.

This product was created with the support of the US Geological Survey Fort Collins Science Center (Cooperative Agreement #G22AC00322).

More information on map development and re-use policy. Raster layers for red brome maps can be downloaded by using the USA-NPN Geoserver Request Builder

Explore the forecast in our Visualization Tool.

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