Algae & red tide, month by month around the world

Blooms that close beaches and clear the water of fish for a few weeks; not the Caribbean weed.

This is a warning page, not a recommendation. Algae & red tide covers 10 destinations on SeasonMap; the months below are the ones in which the risk window is open — most weeks in them pass quietly, and the score beside each place is still the ordinary climate score, hazard and all.

← All seasonsThe world's calendar

When it is on

Number of destinations with algae & red tide on in that month. Windows move a little each year.

Algae & red tide in January

  1. Naples, Florida 🇺🇸 United StatesRed tide risk · 1 Sep – 28 Feb (usually)Blooms of Karenia brevis drift onto this coast most often between autumn and late winter.91
  2. Sarasota 🇺🇸 United StatesRed tide · 1 Sep – 1 Mar (usually)Blooms of Karenia brevis drift inshore in some years, killing fish and putting an irritant in the air along the beach.85
  3. Tampa 🇺🇸 United StatesRed tide season · 1 Sep – 28 Feb (usually)Karenia brevis blooms usually start offshore in the autumn and drift onto the Gulf beaches, killing fish and leaving an aerosol that has people coughing on the sand.84
  4. Clearwater 🇺🇸 United StatesRed tide · 1 Aug – 28 Feb (usually)Blooms drift in most often from late summer into winter, killing fish and putting an irritant in the air that makes the beach unpleasant within minutes.81

What's on around the world in January →

Algae & red tide in February

  1. Sarasota 🇺🇸 United StatesRed tide · 1 Sep – 1 Mar (usually)Blooms of Karenia brevis drift inshore in some years, killing fish and putting an irritant in the air along the beach.92
  2. Tampa 🇺🇸 United StatesRed tide season · 1 Sep – 28 Feb (usually)Karenia brevis blooms usually start offshore in the autumn and drift onto the Gulf beaches, killing fish and leaving an aerosol that has people coughing on the sand.90
  3. Clearwater 🇺🇸 United StatesRed tide · 1 Aug – 28 Feb (usually)Blooms drift in most often from late summer into winter, killing fish and putting an irritant in the air that makes the beach unpleasant within minutes.89
  4. Naples, Florida 🇺🇸 United StatesRed tide risk · 1 Sep – 28 Feb (usually)Blooms of Karenia brevis drift onto this coast most often between autumn and late winter.88
  5. Boracay 🇵🇭 PhilippinesGreen algae on White Beach · 15 Feb – 31 May (usually)A fringe of green weed, locally lumot, grows along the shallows in the hot months and is raked off each morning.70

What's on around the world in February →

Algae & red tide in March

  1. Sarasota 🇺🇸 United StatesRed tide · 1 Sep – 1 Mar (usually)Blooms of Karenia brevis drift inshore in some years, killing fish and putting an irritant in the air along the beach.90
  2. Boracay 🇵🇭 PhilippinesGreen algae on White Beach · 15 Feb – 31 May (usually)A fringe of green weed, locally lumot, grows along the shallows in the hot months and is raked off each morning.74

What's on around the world in March →

Algae & red tide in April

  1. Boracay 🇵🇭 PhilippinesGreen algae on White Beach · 15 Feb – 31 May (usually)A fringe of green weed, locally lumot, grows along the shallows in the hot months and is raked off each morning.72

What's on around the world in April →

Algae & red tide in May

  1. Qingdao 🇨🇳 ChinaGreen algae bloom · 20 May – 15 Aug (usually)Ulva drifts up the Yellow Sea most summers, peaks around June and comes ashore in a green mat that the city clears with diggers.92
  2. Austin 🇺🇸 United StatesBlue-green algae on the lake · 15 May – 31 Oct (usually)The city posts warnings for toxic cyanobacteria on Lady Bird Lake through the warm months.69
  3. Boracay 🇵🇭 PhilippinesGreen algae on White Beach · 15 Feb – 31 May (usually)A fringe of green weed, locally lumot, grows along the shallows in the hot months and is raked off each morning.63

What's on around the world in May →

Algae & red tide in June

  1. Rimini 🇮🇹 ItalyMucilage and algal blooms · 15 Jun – 31 Aug (usually)The northern Adriatic is shallow and warm and in some summers it produces mucilage, a brown gel that clings to swimmers and shuts the water for a few days.86
  2. Qingdao 🇨🇳 ChinaGreen algae bloom · 20 May – 15 Aug (usually)Ulva drifts up the Yellow Sea most summers, peaks around June and comes ashore in a green mat that the city clears with diggers.78
  3. Austin 🇺🇸 United StatesBlue-green algae on the lake · 15 May – 31 Oct (usually)The city posts warnings for toxic cyanobacteria on Lady Bird Lake through the warm months.59

What's on around the world in June →

Algae & red tide in July

  1. Sopot 🇵🇱 PolandBlue-green algae closures · 5 Jul – 31 Aug (usually)A hot, still fortnight turns the shallow Bay of Gdańsk soupy and the sanitary inspectorate closes beaches to swimming — sometimes for days, sometimes most of August.87
  2. Rimini 🇮🇹 ItalyMucilage and algal blooms · 15 Jun – 31 Aug (usually)The northern Adriatic is shallow and warm and in some summers it produces mucilage, a brown gel that clings to swimmers and shuts the water for a few days.79
  3. Qingdao 🇨🇳 ChinaGreen algae bloom · 20 May – 15 Aug (usually)Ulva drifts up the Yellow Sea most summers, peaks around June and comes ashore in a green mat that the city clears with diggers.56
  4. Austin 🇺🇸 United StatesBlue-green algae on the lake · 15 May – 31 Oct (usually)The city posts warnings for toxic cyanobacteria on Lady Bird Lake through the warm months.49

What's on around the world in July →

Algae & red tide in August

  1. Sopot 🇵🇱 PolandBlue-green algae closures · 5 Jul – 31 Aug (usually)A hot, still fortnight turns the shallow Bay of Gdańsk soupy and the sanitary inspectorate closes beaches to swimming — sometimes for days, sometimes most of August.92
  2. Rimini 🇮🇹 ItalyMucilage and algal blooms · 15 Jun – 31 Aug (usually)The northern Adriatic is shallow and warm and in some summers it produces mucilage, a brown gel that clings to swimmers and shuts the water for a few days.79
  3. Qingdao 🇨🇳 ChinaGreen algae bloom · 20 May – 15 Aug (usually)Ulva drifts up the Yellow Sea most summers, peaks around June and comes ashore in a green mat that the city clears with diggers.53
  4. Clearwater 🇺🇸 United StatesRed tide · 1 Aug – 28 Feb (usually)Blooms drift in most often from late summer into winter, killing fish and putting an irritant in the air that makes the beach unpleasant within minutes.52
  5. Pensacola 🇺🇸 United StatesRed tide risk · 1 Aug – 15 Dec (usually)Karenia brevis blooms drift along the Gulf coast in late summer and autumn in some years, killing fish and putting an irritant in the air along the shore.51
  6. Austin 🇺🇸 United StatesBlue-green algae on the lake · 15 May – 31 Oct (usually)The city posts warnings for toxic cyanobacteria on Lady Bird Lake through the warm months.47

What's on around the world in August →

Algae & red tide in September

  1. Austin 🇺🇸 United StatesBlue-green algae on the lake · 15 May – 31 Oct (usually)The city posts warnings for toxic cyanobacteria on Lady Bird Lake through the warm months.66
  2. Pensacola 🇺🇸 United StatesRed tide risk · 1 Aug – 15 Dec (usually)Karenia brevis blooms drift along the Gulf coast in late summer and autumn in some years, killing fish and putting an irritant in the air along the shore.62
  3. Clearwater 🇺🇸 United StatesRed tide · 1 Aug – 28 Feb (usually)Blooms drift in most often from late summer into winter, killing fish and putting an irritant in the air that makes the beach unpleasant within minutes.59
  4. Sarasota 🇺🇸 United StatesRed tide · 1 Sep – 1 Mar (usually)Blooms of Karenia brevis drift inshore in some years, killing fish and putting an irritant in the air along the beach.58
  5. Tampa 🇺🇸 United StatesRed tide season · 1 Sep – 28 Feb (usually)Karenia brevis blooms usually start offshore in the autumn and drift onto the Gulf beaches, killing fish and leaving an aerosol that has people coughing on the sand.57
  6. Naples, Florida 🇺🇸 United StatesRed tide risk · 1 Sep – 28 Feb (usually)Blooms of Karenia brevis drift onto this coast most often between autumn and late winter.55

What's on around the world in September →

Algae & red tide in October

  1. Austin 🇺🇸 United StatesBlue-green algae on the lake · 15 May – 31 Oct (usually)The city posts warnings for toxic cyanobacteria on Lady Bird Lake through the warm months.81
  2. Pensacola 🇺🇸 United StatesRed tide risk · 1 Aug – 15 Dec (usually)Karenia brevis blooms drift along the Gulf coast in late summer and autumn in some years, killing fish and putting an irritant in the air along the shore.80
  3. Tampa 🇺🇸 United StatesRed tide season · 1 Sep – 28 Feb (usually)Karenia brevis blooms usually start offshore in the autumn and drift onto the Gulf beaches, killing fish and leaving an aerosol that has people coughing on the sand.70
  4. Sarasota 🇺🇸 United StatesRed tide · 1 Sep – 1 Mar (usually)Blooms of Karenia brevis drift inshore in some years, killing fish and putting an irritant in the air along the beach.70
  5. Clearwater 🇺🇸 United StatesRed tide · 1 Aug – 28 Feb (usually)Blooms drift in most often from late summer into winter, killing fish and putting an irritant in the air that makes the beach unpleasant within minutes.69
  6. Naples, Florida 🇺🇸 United StatesRed tide risk · 1 Sep – 28 Feb (usually)Blooms of Karenia brevis drift onto this coast most often between autumn and late winter.66

What's on around the world in October →

Algae & red tide in November

  1. Pensacola 🇺🇸 United StatesRed tide risk · 1 Aug – 15 Dec (usually)Karenia brevis blooms drift along the Gulf coast in late summer and autumn in some years, killing fish and putting an irritant in the air along the shore.88
  2. Clearwater 🇺🇸 United StatesRed tide · 1 Aug – 28 Feb (usually)Blooms drift in most often from late summer into winter, killing fish and putting an irritant in the air that makes the beach unpleasant within minutes.85
  3. Tampa 🇺🇸 United StatesRed tide season · 1 Sep – 28 Feb (usually)Karenia brevis blooms usually start offshore in the autumn and drift onto the Gulf beaches, killing fish and leaving an aerosol that has people coughing on the sand.82
  4. Sarasota 🇺🇸 United StatesRed tide · 1 Sep – 1 Mar (usually)Blooms of Karenia brevis drift inshore in some years, killing fish and putting an irritant in the air along the beach.82
  5. Naples, Florida 🇺🇸 United StatesRed tide risk · 1 Sep – 28 Feb (usually)Blooms of Karenia brevis drift onto this coast most often between autumn and late winter.78

What's on around the world in November →

Algae & red tide in December

  1. Sarasota 🇺🇸 United StatesRed tide · 1 Sep – 1 Mar (usually)Blooms of Karenia brevis drift inshore in some years, killing fish and putting an irritant in the air along the beach.88
  2. Tampa 🇺🇸 United StatesRed tide season · 1 Sep – 28 Feb (usually)Karenia brevis blooms usually start offshore in the autumn and drift onto the Gulf beaches, killing fish and leaving an aerosol that has people coughing on the sand.87
  3. Naples, Florida 🇺🇸 United StatesRed tide risk · 1 Sep – 28 Feb (usually)Blooms of Karenia brevis drift onto this coast most often between autumn and late winter.84
  4. Clearwater 🇺🇸 United StatesRed tide · 1 Aug – 28 Feb (usually)Blooms drift in most often from late summer into winter, killing fish and putting an irritant in the air that makes the beach unpleasant within minutes.84
  5. Pensacola 🇺🇸 United StatesRed tide risk · 1 Aug – 15 Dec (usually)Karenia brevis blooms drift along the Gulf coast in late summer and autumn in some years, killing fish and putting an irritant in the air along the shore.74

What's on around the world in December →