Blog

Why Do Florida Properties Overwater Most in the Fall?

Because October Sets a Schedule December Doesn't Need

14 min read Irrigation Managers

By Jon Peters, Founder and General Manager, Irrigation Managers. Nationally Certified Crop Adviser with 33 years in irrigation technology and agronomy.

As of September 30, 2026. SFWMD's year-round landscape watering rules are in effect across Southwest Florida. The Lee and Collier water shortage warning was lifted June 4. NOAA has an El Niño Advisory in place heading into the dry season.

On June 4, 2026, the South Florida Water Management District lifted the water shortage warning it had placed on Lee and Collier counties back in February. The Lower West Coast had picked up 4.46 inches of rain since May 15, more than 140 percent of normal, and Lower Tamiami Aquifer levels rose about three feet.[^1]

That was the rainy season doing its job. According to the National Weather Service, it runs May 15 to October 15 in Southwest Florida.[^2] Two weeks from now, it ends.

What happens next is predictable. The rain stops, the turf starts to look a little tired, and someone turns the controller back up. In October, that's the right call. By December it's the wrong one, and on most properties nobody comes back to turn it down.

That's the fall overwatering problem. It isn't a mistake anyone makes on purpose. It's a schedule that was right for six weeks and then kept running all winter.

Key Takeaways

  • The Southwest Florida rainy season ends around October 15,[^2] and lawn irrigation need rises when it does. In Fort Myers, UF/IFAS puts October's net irrigation requirement at 3.0 inches, higher than any month from June through September.[^3]
  • Then need falls fast. Fort Myers drops from 3.0 inches in October to 1.8 inches in December and January, a 40 percent decline,[^3] while schedules set in October often stay put.
  • University of Florida guidance cited by SWFWMD calls for winter watering every 10 to 14 days.[^4] A two-day-a-week schedule, the legal maximum in many areas,[^5] runs about three to four times that often.
  • Overwatering "greatly increases disease susceptibility and thatch buildup and leads to a shorter root system," according to UF/IFAS.[^6]
  • A very strong El Niño is likely this winter,[^7] and strong El Niño dry seasons have historically brought well above average rainfall to Florida.[^8] That could push actual irrigation need even lower.

What Actually Changes in Southwest Florida in the Fall?

Rain stops doing most of the work in mid-October, so irrigation need jumps briefly, then falls through November and December as temperatures and evapotranspiration drop.

UF/IFAS has calculated the long-term monthly net irrigation requirement for Florida lawns by city. Here is Fort Myers:[^3]

Month Net irrigation requirement (inches) What's happening
July 2.4 Rainy season carries most of the load
August 2.4 Rainy season
September 2.2 Rainy season, tapering
October 3.0 Rain stops mid-month; need jumps
November 2.4 Cooler, shorter days
December 1.8 40% below October
January 1.8 Winter low

Definition, net irrigation requirement: The net irrigation requirement is the amount of water a landscape needs from irrigation after subtracting the rainfall that actually reaches and stays in the root zone. It is plant water use minus effective rainfall.

Definition, evapotranspiration (ET): Evapotranspiration is the total water a landscape loses to evaporation from the soil and transpiration through plant leaves. It is the standard way to estimate how much water plants need, and it falls in Florida's cooler months.

Look at the shape of that table. October is a spike, not a new normal. A property that raises its schedule to meet October and leaves it there is programmed for a month that ends on October 31.

Why Does the Schedule Get Stuck in October?

Because "set it and forget it" is the default on most properties, and in Florida the legal watering days quietly become the schedule, whether the plants need them or not.

SFWMD's year-round landscape irrigation rule limits watering to two or three days a week depending on local ordinance, with no watering between 10 a.m. and 4 p.m.[^5] Those rules set a ceiling. On a lot of properties they've become the floor. If the ordinance allows Wednesday and Saturday, the controller runs Wednesday and Saturday, all year.

Here's the arithmetic for winter:

  • Two days a week is about 8 to 9 irrigation days a month.
  • UF guidance for December through February, as published by the Southwest Florida Water Management District, is "one-half to three-quarters of an inch of water every 10–14 days,"[^4] or about 2 to 3 irrigation days a month.

That's roughly three to four times as many watering days as the guidance calls for, before you count runtime per event. On a three-day-a-week ordinance the gap is wider.

Nobody on the property is doing anything against the rules. That's why it goes unnoticed.

What Does Winter Overwatering Do to a Florida Landscape?

It weakens turf rather than helping it: shallower roots, more thatch, more disease and more weeds, which then look like a reason to water more.

UF/IFAS puts it directly: overwatering "greatly increases disease susceptibility and thatch buildup and leads to a shorter root system, which reduces the turf's overall stress tolerance and ability to survive with less water." The same publication links overwatering to dollarweed and sedges.[^6] SWFWMD's own guidance warns that "overwatering in the winter can encourage pests and disease in your lawn."[^4]

Leaf wetness is part of the mechanism. NC State Extension notes that for brown patch, a Rhizoctonia leaf disease, "the turfgrass leaves must be continuously wet for at least 10 to 12 hours" for infection, and recommends watering just before sunrise rather than in the late afternoon or evening.[^9] Cool, humid winter nights plus extra irrigation keep leaves wet longer.

This is the quiet version of the failure. Nothing floods. The turf just thins out over the winter, weeds move in, and in March the landscape committee asks why the property looks worse after a season of watering on every allowed day.

What Does El Niño Mean for This Dry Season?

It likely means more winter rain than usual in Florida, which lowers irrigation need further and makes a fixed schedule even more wasteful.

On September 10, NOAA's Climate Prediction Center gave a very strong El Niño better than 90 percent odds for fall and winter 2026-27.[^7] According to NWS Melbourne, during strong El Niños such as 1982-83 and 1997-98, "storminess is greatly increased over Florida," leading to "well above average rainfall and perhaps widespread flooding."[^8]

That's a historical pattern, not a guarantee. But it points the same direction as the calendar. A schedule that doesn't respond to rain and ET this winter will be further off than usual.

A rain sensor helps on the days it rains. It doesn't help on the dry, cool days in between, when plants simply need less. That adjustment has to come from the schedule itself.

Before October 15: know your number

The rain is about to stop, and your controller is about to get turned up. The properties that come through the winter looking best won't be the ones that picked the right number of minutes. They'll be the ones with a water use analysis baseline: measured water need, peak demand and seasonal adjustment for every zone, so the schedule steps down as the season does.

Request a water use analysis for your Southwest Florida property →

What Does a Correct Fall Step-Down Look Like?

It raises irrigation briefly when the rain stops, then brings it down in stages through November and December based on ET, not on the calendar of allowed days.

  1. Establish the baseline before you change anything. Know what each zone applied during the rainy season and what it needs going into dry season.
  2. Check uniformity zone by zone. The Irrigation Association's analysis of more than 6,800 audits found average distribution uniformity of about 50 percent,[^10] and EPA sets 65 percent as the commercial minimum.[^11] Poor uniformity is why dry spots push schedules up for the whole zone.
  3. Repair before you re-water. Storm season and mowing leave broken, tilted and buried heads. Fix them before adding runtime.
  4. Step up in October, on ET. Meet the October jump, but set the date you'll step back down.
  5. Step down in November and again in December. Fort Myers need falls 40 percent from October to December.[^3] Your runtimes and days should fall with it.
  6. Use fewer, deeper waterings. Apply one-half to three-quarters of an inch when the turf needs it,[^4][^6] rather than light runs on every allowed day.
  7. Water before sunrise. Keep leaf-wet hours short.[^9]
  8. Watch the turf for real stress signs. UF/IFAS lists folded leaf blades, a blue-gray tint and footprints that stay visible.[^6] Water when you see them, not because it's Wednesday.
  9. Report against the baseline monthly. What isn't measured is an opinion at the next board meeting.

You can look up ET and rainfall for your property with the free ET and rainfall lookup tool on irrmgmt.com.

Who Is Most Exposed Right Now?

HOAs, condominium associations, commercial and institutional campuses, parks and small community golf courses with large turf areas and many zones.

Exposure scales with zone count. Every zone is its own microclimate: full sun, shade under oaks, a berm, a retention pond edge, heat off a parking lot. A single program across 80 zones is wrong in 79 different ways at once, and a program that doesn't change with the season is wrong in all of them for four months straight.

If your property has 50 or more zones and a remote-capable controller, this fall is a genuine decision point.

What Should Florida Property Managers Do in the Next 30 Days?

  • ☐ Pull rainy-season runtimes and water use from the controller and meter.
  • ☐ Walk the property after the last big rains and log broken, tilted and buried heads by zone.
  • ☐ Decide your October increase and put a step-down date on the calendar for November and December.
  • ☐ Move start times before sunrise if any zones run late in the day.
  • ☐ Confirm your local watering days under the SFWMD year-round rule, and treat them as a maximum.
  • ☐ Look up current ET for your site and compare it to your schedule.
  • ☐ Get it into the budget conversation. HOAs and commercial properties: 2027 budgets are being drafted now, in Q4. Florida cities and counties started fiscal year 2027 on October 1,[^12] so this is the time to plan for next year's cycle.

[FOUNDER PARAGRAPH: REQUIRED BEFORE PUBLISH. One or two paragraphs in Jon's words, from his own experience. Do not invent. Suggested prompts for a 15-minute call:

  • What does he typically find in a Florida HOA's controller in January? (Schedules unchanged since fall? Watering every allowed day?)
  • A Southwest Florida property (anonymized is fine) where stepping down in winter improved turf, not just water use.
  • His view as a CCA on why St. Augustinegrass declines under winter overwatering.]

How Irrigation Managers Handles the Florida Fall Transition

Irrigation Managers is a remote irrigation management firm built on agronomy, not plumbing, led by a nationally Certified Crop Adviser with 33 years in irrigation technology and agronomic principles. We work directly with property owners and as a white-label partner to landscape maintenance contractors across Florida.

Our framework is Analyze → Implement → Manage:

  • Analyze: a water use analysis establishing baseline need, peak demand and seasonal adjustment for every site.
  • Implement: system configuration, controller programming and base scheduling built from measured uniformity, plant demand and the legal watering window.
  • Manage: 24/7 proactive monitoring, fault and alert routing, ongoing optimization including seasonal step-downs, and branded report cards comparing performance to your baseline.

The goal is consistent, healthy turf and plantings across every zone, all year. Many clients also cut water waste by 50 percent or more along the way. That's the bonus, not the pitch.

Guided programs start as low as $1 per zone per month. Full irrigation management, including monitoring and reporting, starts as low as $5 per zone per month.

The rain stops around October 15. Your landscape's need drops 40 percent by December. The schedule should move with both.

Request a Water Use Analysis →

Frequently Asked Questions

How often should I water my lawn in Southwest Florida in the winter? Less often than in summer. UF guidance published by the Southwest Florida Water Management District recommends one-half to three-quarters of an inch of water every 10 to 14 days in December, January and February. Watering on every allowed day under a two-day-a-week rule works out to about three to four times that frequency. Water when turf shows stress (folded blades, a blue-gray tint, footprints that stay visible), always before sunrise, and within your local watering days.

When does the rainy season end in Southwest Florida? The National Weather Service puts the Southwest Florida rainy season at May 15 to October 15. After mid-October, rain stops meeting most of a landscape's water needs, so irrigation need rises for a few weeks. It then falls through November and December as temperatures and evapotranspiration drop.

What are the watering restrictions in Lee and Collier counties right now? As of September 30, 2026, SFWMD's year-round landscape irrigation rule applies: two or three days a week depending on local ordinance, with no watering between 10 a.m. and 4 p.m. The water shortage warning for Lee and Collier counties was lifted June 4, 2026. A Modified Phase II order remains for private Mid-Hawthorn Aquifer wells in northeastern Cape Coral. Check SFWMD and your local government for current rules before changing schedules.

Why is my lawn getting worse in winter when we water every day we're allowed? Because more water isn't what winter turf needs. UF/IFAS says overwatering increases disease susceptibility and thatch and shortens roots, and it encourages dollarweed and sedges. Uniformity also plays a role: average distribution uniformity in landscape systems is about 50 percent, so dry spots push the schedule up for the whole zone while the rest stays too wet. The fix is fewer, deeper waterings before sunrise, based on ET, plus repairs and uniformity improvements.

Does El Niño change how I should water this winter? It may. NOAA gave a very strong El Niño better than 90 percent odds for winter 2026-27 as of September 10, 2026. Historically, strong El Niños have brought well above average dry-season rainfall to Florida, according to NWS Melbourne. That's not a guarantee, but it means a schedule that doesn't respond to rain and ET could overwater even more than usual this winter.

What size property benefits from a water use analysis? Properties with 50 or more zones and a remote-capable controller, such as HOAs, condominium associations, commercial campuses, parks and community golf courses, benefit most, because differences between zones add up across the site. Irrigation Managers' guided programs start as low as $1 per zone per month, and full irrigation management starts as low as $5 per zone per month.

References

[^1]: South Florida Water Management District, SFWMD Rescinds Water Shortage Warning for Lee and Collier Counties, June 4, 2026. https://sfwmd.gov/news-events/news/sfwmd-rescinds-water-shortage-warning-lee-and-collier-counties

[^2]: National Weather Service Tampa Bay, Rainy Season. https://weather.gov/tbw/rainyseason

[^3]: Consuelo C. Romero, Bernard Cardenas and Michael D. Dukes, Net Irrigation Requirements for Florida Turfgrass Lawns: Part 3, Theoretical Irrigation Requirements (AE482), UF/IFAS Extension, revised August 2024, Table 4. https://ask.ifas.ufl.edu/publication/AE482

[^4]: Southwest Florida Water Management District, Overwatering in Winter Can Encourage Pests and Disease, WaterMatters Magazine, July 19, 2018. https://www.swfwmd.state.fl.us/blog/watermatters-magazine/45/skip-week-watering-healthier-lawn

[^5]: South Florida Water Management District, Landscape Watering Restrictions, updated June 4, 2026. https://www.sfwmd.gov/community-residents/landscape-irrigation

[^6]: Laurie E. Trenholm, J. Bryan Unruh and John L. Cisar, Watering Your Florida Lawn (ENH9/LH025), UF/IFAS Extension, January 31, 2017. https://ask.ifas.ufl.edu/publication/LH025

[^7]: NOAA Climate Prediction Center, ENSO Diagnostic Discussion, issued September 10, 2026. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml

[^8]: National Weather Service Melbourne, Florida Dry Season Rainfall and El Niño-Southern Oscillation (ENSO), September 24, 2016. https://www.weather.gov/mlb/enso_florida_rainfall

[^9]: Lee Butler and Jim Kerns, Brown Patch in Turf, NC State Extension, reviewed December 16, 2019. https://content.ces.ncsu.edu/brown-patch-in-turf

[^10]: Brent Mecham, Using Distribution Uniformity to Evaluate the Quality of a Sprinkler System, Irrigation Association, 2004. https://www.irrigation.org/IA/FileUploads/IA/Resources/TechnicalPapers/2004/UsingDistributionUniformityToEvaluateTheQualityOfASprinklerSystem.pdf

[^11]: U.S. EPA WaterSense, WaterSense at Work, Section 5.3: Irrigation, 2023. https://www.epa.gov/system/files/documents/2023-05/ws-commercial-watersense-at-work_Section_5.3_Irrigation.pdf

[^12]: Florida Statutes, Section 218.33(1): "Each local governmental entity shall begin its fiscal year on October 1 of each year and end it on September 30." http://www.leg.state.fl.us/statutes/index.cfm?App_mode=Display_Statute&URL=0200-0299/0218/Sections/0218.33.html