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Lake Monroe algae history from satellite

We read Lake Monroe from 401 cloud-free satellite scenes between Apr 14, 2016 – Oct 1, 2026. Here is what the surface water showed.

Clear scenes
401
Typical (median), index
26
Highest reading
230 · Apr 19, 2017
Latest scene
16 · Oct 1, 2026

Algae signal (red-edge index) over time

01002003002017201820192020202120222023202420252026Apr 14, 2016: 20 index (low)May 14, 2016: 25 index (low)Jun 23, 2016: 57 index (low)Jul 13, 2016: 45 index (low)Aug 2, 2016: 39 index (low)Sep 11, 2016: 33 index (low)Oct 1, 2016: 25 index (low)Oct 21, 2016: 11 index (low)Nov 10, 2016: 2.5 index (low)Nov 20, 2016: 8.5 index (low)Nov 30, 2016: 21 index (low)Feb 8, 2017: 48 index (low)Mar 10, 2017: 38 index (low)Mar 30, 2017: 62 index (low)Apr 19, 2017: 230 index (high)May 9, 2017: 75 index (high)Jun 18, 2017: 76 index (low)Aug 17, 2017: 15 index (low)Sep 21, 2017: 13 index (low)Sep 26, 2017: 3.3 index (low)Oct 16, 2017: 6 index (low)Oct 31, 2017: 0.3 index (low)Nov 20, 2017: 1.5 index (low)Nov 25, 2017: 3 index (low)Nov 30, 2017: 0.5 index (low)Dec 10, 2017: 13 index (low)Dec 20, 2017: 5.5 index (low)Dec 30, 2017: 0.5 index (low)Jan 4, 2018: 20 index (low)Jan 9, 2018: 13 index (low)Jan 24, 2018: 13 index (low)Feb 18, 2018: 21 index (low)Feb 28, 2018: 21 index (low)Mar 5, 2018: 25 index (low)Mar 15, 2018: 34 index (low)Mar 25, 2018: 70 index (high)Mar 30, 2018: 66 index (low)Apr 4, 2018: 70 index (high)Apr 9, 2018: 118 index (low)Apr 14, 2018: 138 index (low)Apr 19, 2018: 117 index (low)Apr 24, 2018: 132 index (low)Apr 29, 2018: 169 index (high)May 4, 2018: 222 index (high)May 9, 2018: 163 index (low)May 24, 2018: 63 index (high)Jun 18, 2018: 61 index (low)Jun 23, 2018: 74 index (low)Jun 28, 2018: 68 index (low)Aug 2, 2018: 44 index (low)Aug 7, 2018: 16 index (low)Aug 12, 2018: 18 index (low)Aug 17, 2018: 29 index (low)Aug 27, 2018: 23 index (low)Sep 1, 2018: 40 index (low)Sep 6, 2018: 21 index (low)Sep 11, 2018: 10 index (low)Sep 16, 2018: 18 index (low)Sep 21, 2018: 13 index (low)Sep 26, 2018: 8.5 index (low)Oct 6, 2018: 14 index (low)Oct 16, 2018: 12 index (low)Oct 21, 2018: 9.8 index (low)Oct 31, 2018: 10 index (low)Nov 15, 2018: 28 index (low)Nov 30, 2018: 31 index (low)Dec 5, 2018: 21 index (low)Dec 10, 2018: 30 index (low)Dec 25, 2018: 25 index (low)Dec 30, 2018: 27 index (low)Jan 4, 2019: 25 index (low)Jan 29, 2019: 40 index (low)Feb 8, 2019: 23 index (low)Feb 23, 2019: 26 index (low)Mar 10, 2019: 20 index (low)Mar 25, 2019: 21 index (low)Apr 4, 2019: 34 index (low)Apr 24, 2019: 69 index (high)Apr 29, 2019: 132 index (low)May 19, 2019: 69 index (high)May 24, 2019: 92 index (low)May 29, 2019: 122 index (low)Jun 3, 2019: 143 index (low)Jun 13, 2019: 99 index (high)Jun 18, 2019: 136 index (low)Jun 23, 2019: 124 index (low)Jun 28, 2019: 139 index (low)Jul 3, 2019: 87 index (low)Jul 23, 2019: 27 index (low)Jul 28, 2019: 28 index (low)Aug 12, 2019: 24 index (low)Aug 22, 2019: 22 index (low)Aug 27, 2019: 11 index (low)Sep 11, 2019: 12 index (low)Sep 16, 2019: 21 index (low)Sep 21, 2019: 11 index (low)Oct 11, 2019: 6 index (low)Oct 26, 2019: 11 index (low)Nov 10, 2019: 17 index (low)Nov 20, 2019: 0 index (low)Nov 25, 2019: 20 index (low)Nov 30, 2019: 2.3 index (low)Dec 5, 2019: 14 index (low)Dec 10, 2019: 15 index (low)Dec 15, 2019: 14 index (low)Dec 25, 2019: 24 index (low)Jan 9, 2020: 13 index (low)Jan 14, 2020: 69 index (low)Jan 24, 2020: 12 index (low)Feb 3, 2020: 8.5 index (low)Feb 8, 2020: 28 index (low)Feb 18, 2020: 24 index (low)Feb 23, 2020: 27 index (low)Feb 28, 2020: 20 index (low)Mar 4, 2020: 98 index (high)Mar 14, 2020: 26 index (low)Mar 19, 2020: 26 index (low)Mar 24, 2020: 20 index (low)Mar 29, 2020: 21 index (low)Apr 3, 2020: 20 index (low)Apr 8, 2020: 35 index (low)Apr 13, 2020: 57 index (low)Apr 28, 2020: 55 index (low)May 3, 2020: 32 index (low)May 13, 2020: 98 index (low)Jun 17, 2020: 74 index (low)Jun 22, 2020: 60 index (high)Jul 2, 2020: 94 index (low)Jul 7, 2020: 93 index (low)Jul 12, 2020: 63 index (low)Jul 17, 2020: 79 index (low)Jul 27, 2020: 44 index (low)Aug 1, 2020: 49 index (low)Aug 11, 2020: 41 index (low)Aug 16, 2020: 32 index (low)Aug 26, 2020: 38 index (low)Sep 5, 2020: 9.8 index (low)Sep 25, 2020: 5.3 index (low)Oct 15, 2020: 4.8 index (low)Oct 25, 2020: 3.8 index (low)Oct 30, 2020: 9.5 index (low)Nov 4, 2020: 5.8 index (low)Nov 14, 2020: 11 index (low)Dec 9, 2020: 2.8 index (low)Dec 29, 2020: 4.5 index (low)Jan 8, 2021: 5.5 index (low)Jan 18, 2021: 7.5 index (low)Jan 28, 2021: 17 index (low)Feb 2, 2021: 22 index (low)Feb 7, 2021: 30 index (low)Feb 12, 2021: 23 index (low)Feb 22, 2021: 19 index (low)Feb 27, 2021: 15 index (low)Mar 4, 2021: 17 index (low)Mar 9, 2021: 19 index (low)Mar 14, 2021: 11 index (low)Mar 19, 2021: 35 index (low)Mar 24, 2021: 20 index (low)Apr 8, 2021: 21 index (low)Apr 13, 2021: 35 index (low)Apr 23, 2021: 57 index (low)Apr 28, 2021: 65 index (low)May 3, 2021: 70 index (low)May 8, 2021: 33 index (low)May 23, 2021: 35 index (low)May 28, 2021: 40 index (low)Jun 2, 2021: 96 index (low)Jun 12, 2021: 120 index (low)Jun 27, 2021: 111 index (low)Jul 2, 2021: 98 index (low)Jul 17, 2021: 33 index (low)Jul 22, 2021: 54 index (low)Jul 27, 2021: 45 index (low)Aug 6, 2021: 49 index (low)Aug 21, 2021: 11 index (low)Sep 15, 2021: 18 index (low)Sep 25, 2021: 9.8 index (low)Sep 30, 2021: 9.5 index (low)Oct 5, 2021: 9.8 index (low)Oct 10, 2021: 9.3 index (low)Oct 15, 2021: 3 index (low)Oct 30, 2021: 8 index (low)Nov 9, 2021: 11 index (low)Nov 14, 2021: 3.3 index (low)Nov 24, 2021: 7.3 index (low)Nov 29, 2021: -1.2 index (low)Dec 4, 2021: 3 index (low)Dec 14, 2021: 21 index (low)Dec 19, 2021: 37 index (low)Dec 24, 2021: 4 index (low)Dec 29, 2021: -0.7 index (low)Jan 3, 2022: 12 index (low)Jan 8, 2022: 5 index (low)Jan 13, 2022: 7.3 index (low)Jan 18, 2022: 15 index (low)Feb 12, 2022: 11 index (low)Feb 22, 2022: 22 index (low)Feb 27, 2022: 23 index (low)Mar 4, 2022: 17 index (low)Mar 19, 2022: 39 index (low)Mar 29, 2022: 16 index (low)Apr 3, 2022: 24 index (low)Apr 8, 2022: 33 index (low)May 8, 2022: 60 index (low)May 13, 2022: 21 index (low)May 18, 2022: 28 index (low)May 23, 2022: 84 index (low)Jun 2, 2022: 94 index (low)Jun 7, 2022: 42 index (low)Jul 12, 2022: 101 index (low)Jul 22, 2022: 99 index (low)Jul 27, 2022: 76 index (low)Aug 1, 2022: 51 index (high)Aug 16, 2022: 57 index (low)Aug 21, 2022: 49 index (low)Aug 26, 2022: 51 index (high)Sep 5, 2022: 26 index (low)Sep 10, 2022: 38 index (low)Sep 15, 2022: 20 index (low)Sep 20, 2022: 15 index (low)Sep 30, 2022: 49 index (low)Oct 5, 2022: 5 index (low)Oct 10, 2022: 8.1 index (low)Oct 20, 2022: 2.8 index (low)Oct 25, 2022: 0.3 index (low)Oct 30, 2022: 6.8 index (low)Nov 14, 2022: 9.3 index (low)Nov 29, 2022: -0.5 index (low)Dec 4, 2022: 15 index (low)Dec 9, 2022: 3 index (low)Dec 19, 2022: 1.5 index (low)Dec 24, 2022: 9.5 index (low)Dec 29, 2022: 5.5 index (low)Jan 3, 2023: 6.5 index (low)Jan 8, 2023: 4 index (low)Jan 28, 2023: 13 index (low)Feb 17, 2023: 36 index (low)Feb 22, 2023: 33 index (low)Feb 27, 2023: 43 index (low)Mar 4, 2023: 64 index (low)Mar 9, 2023: 49 index (low)Mar 14, 2023: 45 index (low)Mar 24, 2023: 44 index (low)Mar 29, 2023: 65 index (low)Apr 13, 2023: 93 index (low)Apr 18, 2023: 73 index (low)Apr 23, 2023: 91 index (low)May 3, 2023: 86 index (low)May 8, 2023: 63 index (high)May 13, 2023: 75 index (high)May 18, 2023: 75 index (high)May 28, 2023: 93 index (low)Jun 12, 2023: 151 index (low)Jun 27, 2023: 143 index (low)Jul 22, 2023: 84 index (low)Aug 6, 2023: 49 index (low)Aug 11, 2023: 17 index (low)Aug 16, 2023: 29 index (low)Aug 21, 2023: 52 index (low)Aug 26, 2023: 32 index (low)Aug 31, 2023: 27 index (low)Sep 5, 2023: 14 index (low)Sep 10, 2023: 8.9 index (low)Sep 15, 2023: 12 index (low)Sep 20, 2023: 14 index (low)Oct 5, 2023: 18 index (low)Oct 15, 2023: 6.8 index (low)Oct 20, 2023: 1 index (low)Oct 30, 2023: 2.4 index (low)Nov 9, 2023: 2.5 index (low)Nov 19, 2023: 3.5 index (low)Nov 29, 2023: 15 index (low)Dec 9, 2023: 6.5 index (low)Dec 19, 2023: 21 index (low)Dec 29, 2023: -0.5 index (low)Feb 7, 2024: 52 index (high)Feb 12, 2024: 22 index (low)Feb 22, 2024: 23 index (low)Feb 27, 2024: 8.3 index (low)Mar 8, 2024: 15 index (low)Mar 18, 2024: 20 index (low)Mar 23, 2024: 33 index (low)Apr 7, 2024: 20 index (low)Apr 12, 2024: 52 index (low)Apr 17, 2024: 60 index (low)Apr 22, 2024: -199.6 index (low)May 2, 2024: 63 index (high)May 7, 2024: 81 index (high)May 22, 2024: 133 index (low)May 27, 2024: 103 index (low)Jun 16, 2024: 52 index (high)Jun 26, 2024: 46 index (low)Jul 1, 2024: 96 index (low)Jul 6, 2024: 41 index (low)Jul 26, 2024: 46 index (low)Aug 25, 2024: 63 index (high)Aug 30, 2024: 66 index (low)Sep 24, 2024: 15 index (low)Sep 29, 2024: 15 index (low)Oct 4, 2024: 13 index (low)Oct 14, 2024: 11 index (low)Oct 24, 2024: 1 index (low)Oct 29, 2024: 5.5 index (low)Nov 3, 2024: 10 index (low)Nov 13, 2024: 13 index (low)Nov 18, 2024: 3.5 index (low)Nov 23, 2024: 41 index (low)Nov 28, 2024: 0 index (low)Dec 3, 2024: -1.5 index (low)Dec 8, 2024: 42 index (low)Dec 13, 2024: 4.3 index (low)Dec 23, 2024: 4.8 index (low)Jan 2, 2025: -0.7 index (low)Jan 12, 2025: 21 index (low)Jan 17, 2025: 5.3 index (low)Feb 6, 2025: 16 index (low)Feb 21, 2025: 23 index (low)Feb 26, 2025: 18 index (low)Mar 3, 2025: 17 index (low)Mar 8, 2025: 29 index (low)Mar 13, 2025: 37 index (low)Mar 18, 2025: 34 index (low)Apr 2, 2025: 55 index (low)Apr 7, 2025: 59 index (low)Apr 12, 2025: 41 index (low)Apr 17, 2025: 19 index (low)Apr 27, 2025: 41 index (low)May 2, 2025: 71 index (low)May 9, 2025: 91 index (high)May 17, 2025: 128 index (low)May 22, 2025: 112 index (low)May 29, 2025: 149 index (high)Jun 1, 2025: 117 index (high)Jun 18, 2025: 146 index (high)Jun 26, 2025: 151 index (low)Jul 1, 2025: 145 index (low)Jul 6, 2025: 139 index (low)Jul 11, 2025: 110 index (high)Jul 16, 2025: 91 index (low)Jul 21, 2025: 83 index (low)Jul 26, 2025: 49 index (low)Jul 28, 2025: 25 index (low)Jul 31, 2025: 42 index (low)Aug 5, 2025: 15 index (low)Aug 15, 2025: 17 index (low)Aug 20, 2025: 31 index (low)Sep 6, 2025: 8.8 index (low)Sep 19, 2025: 13 index (low)Sep 24, 2025: 6 index (low)Sep 26, 2025: 10 index (low)Oct 14, 2025: 5 index (low)Oct 16, 2025: 8.8 index (low)Oct 19, 2025: 7 index (low)Oct 24, 2025: 4.3 index (low)Oct 29, 2025: 2 index (low)Nov 3, 2025: 5.3 index (low)Nov 5, 2025: 3.8 index (low)Nov 8, 2025: 3.5 index (low)Nov 13, 2025: 29 index (low)Nov 18, 2025: 0.8 index (low)Nov 25, 2025: 4.8 index (low)Nov 28, 2025: 22 index (low)Dec 3, 2025: 12 index (low)Dec 13, 2025: 31 index (low)Dec 23, 2025: 32 index (low)Dec 28, 2025: 9.3 index (low)Jan 7, 2026: 25 index (low)Jan 22, 2026: 26 index (low)Jan 27, 2026: 19 index (low)Feb 1, 2026: 76 index (high)Feb 6, 2026: 35 index (low)Feb 21, 2026: 31 index (low)Feb 26, 2026: 29 index (low)Mar 8, 2026: 39 index (low)Mar 15, 2026: 53 index (low)Mar 18, 2026: 46 index (low)Mar 28, 2026: 33 index (low)Apr 4, 2026: 60 index (low)Apr 12, 2026: 56 index (low)Apr 17, 2026: 46 index (low)Apr 24, 2026: 67 index (high)Apr 27, 2026: 107 index (low)May 7, 2026: 114 index (low)May 14, 2026: 158 index (low)May 17, 2026: 183 index (low)May 22, 2026: 118 index (low)Jun 11, 2026: 65 index (low)Jun 16, 2026: 145 index (low)Jun 21, 2026: 133 index (low)Jun 23, 2026: 160 index (low)Jun 26, 2026: 126 index (high)Jul 1, 2026: 120 index (low)Jul 11, 2026: 81 index (high)Jul 21, 2026: 96 index (low)Aug 15, 2026: 42 index (low)Aug 22, 2026: 45 index (low)Sep 4, 2026: 42 index (low)Sep 14, 2026: 23 index (low)Sep 19, 2026: 9.3 index (low)Sep 29, 2026: 8 index (low)Oct 1, 2026: 16 index (low)
Algae signal (red-edge index), index. One dot per cloud-free scene; dates are local to the lake.

When it peaks

MonthClear scenesMedian, indexScenes rated high
Jan24130%
Feb32236%
Mar37335%
Apr385713%
May368231%
Jun2911121%
Jul31816%
Aug33329%
Sep36130%
Oct366.90%
Nov355.30%
Dec34110%

By year (median / highest): 2016: 25 / 57 (11 scenes) · 2017: 13 / 230 (17 scenes) · 2018: 27 / 222 (42 scenes) · 2019: 24 / 143 (36 scenes) · 2020: 27 / 98 (39 scenes) · 2021: 20 / 120 (46 scenes) · 2022: 21 / 101 (42 scenes) · 2023: 33 / 151 (42 scenes) · 2024: 22 / 133 (37 scenes) · 2025: 24 / 151 (54 scenes) · 2026: 53 / 183 (35 scenes).

What a satellite can and can’t tell you

Satellites see only the surface layer, only on cloud-free days, and only away from the shoreline. They estimate algae; they do not measure toxins, and they can’t see what the lake bottom is doing. A clear reading is not a safety clearance.

For current conditions and health advisories, check the Florida DEP algal bloom page and the Florida Department of Health. If a person or pet may have been exposed to a bloom, call a doctor, a veterinarian, or Poison Help at 1-800-222-1222.

Source: Sentinel-2 MSI (ESA Copernicus), Red-edge cyanobacteria index (CI-cyano); a scene counts as a bloom when the index is above 50 and stays high relative to turbidity (bloom rule v1 (2026-10)). Snapshot exported Oct 9, 2026.

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