Historic rainfall and flooding from Hurricane Milton

Southwest Florida Water Management District (SWFWMD)
Hurricane Milton Post-Storm Resource, October 17, 2024

Many rivers in the Tampa Bay region have been severely impacted by flooding from Hurricane Milton. The only flood records higher than what we are experiencing now were in the early 1930s.

The region received above average rainfall in its rainy season of June through September, 2024, and its lakes, streams, ponds, wetlands and aquifer levels were already full before Hurricane Milton brought a tremendous amount of rain to the region.

Preliminary data shows Hurricane Milton brought 10-15 inches of rainfall, with pockets of 18 inches in some areas. See the graphic for preliminary data from Oct. 9 and 10, 2024.

Water flows across land and through waterbodies as it moves toward a common body of water, such as a stream, river, lake or coast. When those bodies of water have already reached capacity, there’s nowhere for the water to go, except to flood the land, which can continue for days and weeks following a storm event such as Hurricane Milton.

Places that haven't flooded in decades are now inundated with water.
Some areas that didn't receive as much rainfall are still filling up, as water continues to move across the land.

It will take time for the floodwaters in many of these areas to recede from the historic flooding our region is experiencing due to historic rainfall.

Hydrologic Conditions – Rainfall Overviews

National Weather Service Data (as of Oct. 17, 2024)

According to the US National Weather Service Tampa Bay Florida, much of the region is receiving well above normal rainfall this year. In fact, Tampa has already set a New Yearly Rainfall record at 77.41 inches through Oct. 15 breaking the old record of 76.57 inches set in 1957, which was for the entire calendar year. The rainfall total (30.66 inches) for January through Oct. 15, 2023, was 46.75 inches less than that timeframe for 2024.

According to the US National Weather Service Tampa Bay Florida, their Tampa station has received nearly 33 inches of rain above the normal amount from Jan. 1 through Oct. 15 of this year.

According to the US National Weather Service Tampa Bay Florida, their Lakeland Linder station has received more than 20 inches of rain above the normal amount from Jan. 1 through Oct. 15 of this year.

According to the US National Weather Service Tampa Bay Florida, rainfall amounts are more than double the amounts for last year from Jan. 1 through Oct. 15, 2024 even triple at their Sarasota-Bradenton station.

District Regional Summer Rainfall by Inches

The District has a network of 171 total near-real time rain gauges that collect rainfall data.

According to the Southwest Florida Water Management District, the region has received almost 9 inches above average rainfall for June through October 2024 by the first half of October alone.

The Tampa Bay Region (Hillsborough, Pasco, Pinellas and Polk counties) had about 5.5 inches above average rainfall in June through September 2024 before Hurricane Milton brought a tremendous amount of rain to the region.

The District’s Southern Region (Charlotte, DeSoto, Hardee, Highlands, Manatee and Sarasota counties) had more than 6 inches above average rainfall in June through September 2024 before Hurricane Milton brought a tremendous amount of rain to the region.

The District’s Northern Region (Citrus, Hernando, Lake, Levy, Marion and Sumter counties) had nearly 3 inches above average rainfall in June through September 2024 before Hurricane Milton brought a tremendous amount of rain to the region.

District Regional October Data

According to the Southwest Florida Water Management District, the region has received three times its monthly rainfall average for October 2024 in the first half of the month alone, according to preliminary data.

The Tampa Bay Region (Hillsborough, Pasco, Pinellas and Polk counties) received nearly four times its monthly rainfall average for October in the first half of the month alone according to preliminary data from the Southwest Florida Water Management District.

The District’s Southern Region (Charlotte, DeSoto, Hardee, Highlands, Manatee and Sarasota counties) received more than two times its monthly rainfall average for October 2024 in the first half of the month alone according to preliminary data from the Southwest Florida Water Management District.

The District’s Northern Region (Citrus, Hernando, Lake, Levy, Marion and Sumter counties) received more than 2.5 times its monthly rainfall average for October 2024 in the first half of the month alone, according to preliminary data from the Southwest Florida Water Management District.

District Structures

The Southwest Florida Water Management District does not have the ability to control water on all rivers and water bodies throughout its 16-county region.

It can control water flows in some areas through 84 structures it maintains and operates. These structures help provide flood protection, manage lake water levels and prevent salt water from flowing up freshwater streams and creeks.

Before Hurricane Milton arrived, the District lowered water levels on all structures it operates to make room to accommodate as much water as possible.

These water bodies were full due to above average rainfall received this rainy season of June through September, but the District did all it could to move out water where it has structures.

Learn more about the structures in each county at
https://www.swfwmd.state.fl.us/about/newsroom/district-water-control-structures.

Withlacoochee River/Green Swamp

The Withlacoochee River is experiencing historical flooding. The Withlacoochee River begins in the Green Swamp, which received record rainfall. Some areas of the Green Swamp received close to 16 inches of rain.

Above average rainfall this summer had already saturated soils and filled wetlands and swamps that are no longer able to store additional rainfall.
The Withlacoochee River naturally floods when its watershed is saturated and continues to receive high rainfall.

The Green Swamp lies between Tampa and Orlando in 560,000 acres of Florida backcountry and includes portions of Polk, Lake, Sumter, Hernando and Pasco counties.

It is an area of ecological and hydrologic importance because of its ability to store surface water and slow floodwaters.

In addition to the Withlacoochee River, the Hillsborough, Ocklawaha and Peace rivers all emerge from the Green Swamp. The Hillsborough River is also seeing record highs near Zephyrhills.