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The U.S. government is closed. This site will not be updated; however, NOAA websites and social media channels necessary to protect lives and property will be maintained. To learn more, visit commerce.gov. 

For the latest forecasts and critical weather information, visit weather.gov.

Lake Erie Harmful Algal Bloom Forecast

NOAA provides forecasts for seasonal blooms of cyanobacteria (blue-green algae) in Lake Erie, typically from July to October when warmer water creates favorable bloom conditions. Western Lake Erie has been plagued by an increase of HABs intensity over the past decade. These blooms consist of cyanobacteria or blue-green algae, which are capable of producing toxins that pose a risk to human and animal health, foul coastlines, and impact communities and businesses that depend on the lake. A combination of satellite image (for bloom location and extent), a forecasting and mixing model provide information on the current status of the bloom, forecasted position both at the surface and at depth, and toxicity from field samples. See individual products and our FAQs for more information. For our Lake Erie Hypoxia forecast click here.

Forecast Products

Download Latest Forecast Bulletin
Access Archived Forecast Bulletin for the Bloom Season

The cyanobacteria bloom is present in western Lake Erie but cloud cover or winds above 9.0 mph prevent determining the area. No recent toxin data currently available for western Lake Erie. Due to a lapse in federal funding, we are suspending manual forecast updates for the Lake Erie HAB Forecast until new appropriations are enacted. We will continue to provide automated forecasts and satellite imagery on our website, as we are able, during the lapse in appropriations. -NCCOS HAB Forecasting Team, 01 Oct. 2025
The past few days of imagery can be seen at the HAB monitoring site. The Lake Erie Forecast is operated by the National Centers for Coastal Ocean Science. Contact hab@noaa.gov for technical Questions. Last Updated: 2025-11-11 05 PM EST

Observed Bloom Position

(from most recent satellite image)

Current satellite imagery from the Ocean Land Color Imager (OLCI) and true color imagery showing bloom location and extent.
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Forecasted Bloom Position

(from modeling)

Forecasted extent and position of the bloom for a minimum of 96 hours, based on a combination of a hydrodynamic modeled currents and satellite imagery for initial bloom location.
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Vertical Mixing Forecast

Forecast of the potential for mixing over the next at least 96 hours, to determine the likelihood that the bloom is at the surface or subsurface.
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HAB Alerts

HABs in Lake Erie pose a risk to human and animal health, foul coastlines, and negatively impact communities and businesses. Sign up to receive Lake Erie HAB updates via email.

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2025 Western Lake Erie Projections

The early season projection estimates bloom severity based on Maumee River discharge and modeled phosphorus loads. It is issued weekly from May until the seasonal forecast is announced.

2025 Lake Erie Seasonal Forecast Event

The official seasonal forecast for Lake Erie was announced on June 26, 2025 during a live webinar hosted in collaboration with Ohio Sea Grant. A recording of the event can be found here.

Western Lake Erie Bloom Severity Index (SI)

Following the 2024 Microcystis bloom, we reprocessed the satellite remote sensing time series used to monitor the severity and impacts of annually occurring cyanobacteria (Microcystis) HABs. The satellite reprocessing included new calibrations and improved algorithms, generating a more consistent data set for HAB monitoring in Lake Erie. You can find more information about the updated time series here. In addition, Ohio Sea Grant hosted a webinar on the time series update (recorded presentation here).

The new time series was used to re-evaluate the historical cyanobacteria bloom severity index (SI) for Lake Erie. The SI is based on the quantity (biomass) of the bloom over a sustained 30 day period and is scaled to the minimum observed bloom biomass (2005) and maximum observed bloom biomass (2011) to date. More information about the SI can be found in Stumpf et al. 2016.

Please find the updated Lake Erie SI time series here. When using this data, please use the following attribution:
The Lake Erie Severity Index (SI) is derived from NOAA’s National Centers for Coastal Ocean Science HAB Monitoring Program.

Additional Resources
For other data on Lake Erie HABs, visit one of these websites:

For safety information on these blooms, visit the Ohio EPA website.