Red tide damages oxygen levels in the water which affects marine life. If one consumes fish or shellfish that has been affected by red tide, there will be tingling in the lips, tongue and face. There could also be difficulty breathing, dizziness and vomiting. The symptoms usually appear within 30-60 minutes after ingestion. The preferred basic treatment is to induce vomiting by administering warm salt water (from a clean source) and seek the attention of a doctor immediately. The best way to know if red tide is in effect for Banderas Bay is to do a simple Google search: red tide in PV (and the month and year you are inquiring about). The local papers will report it.
Typically, rainy season starts in June and ends the middle of October. June is the warmest month but September is the most humid. The rain showers are usually hard and fast.
In general, the best weather starts towards the middle of October and goes through the end of June. During this time, the sun shines, there is little to no rain, little to no humidity. The average daily temperature is around 86°. June is the hottest month and when the rainy season starts. September is the most humid month. The rains come and go quickly but they can be furious. Most welcome the rain to cool down the temps.