water temperature in key west

Water Temperature in Key West: Year-Round Guide

The Florida Keys, a stunning archipelago stretching off the southern tip of Florida, is renowned for its year-round warm waters. This guide provides a detailed overview of the water temperatures in the Florida Keys, with a specific focus on Key West, helping you plan the perfect aquatic adventure.

Monthly Water Temperature Overview

January – February: Winter Warmth

  • Temperature Range: 70-74°F (21-23°C)
  • Despite being winter, Key West waters remain comfortably warm, making it ideal for a refreshing swim or snorkeling.

March – April: Spring Awakening

  • Temperature Range: 74-78°F (23-26°C)
  • As spring arrives, water temperatures rise, making it perfect for divers and snorkelers to explore the vibrant marine life.

May – June: Pre-Summer Splash

  • Temperature Range: 78-82°F (26-28°C)
  • With the approach of summer, water temperatures climb, creating excellent conditions for kayaking and paddleboarding.

July – August: Summer Serenity

  • Temperature Range: 82-87°F (28-31°C)
  • Peak summer months offer the warmest waters, ideal for diving into crystal-clear seas and exploring coral reefs.

September – October: Fall Bliss

  • Temperature Range: 80-84°F (27-29°C)
  • Even in fall, the waters remain warm and inviting, perfect for continued aquatic activities.

November – December: Tropical Winter Retreat

  • Temperature Range: 74-78°F (23-26°C)
  • As the year ends, the water temperatures cool slightly but remain warm enough for enjoyable swimming and snorkeling.

Why is Key West Warm Year-Round?

Key West benefits from its geographical location and the Gulf Stream, a powerful warm ocean current originating in the Gulf of Mexico. This current maintains consistently higher temperatures, preventing extreme fluctuations and ensuring warm waters throughout the year. The tropical savanna climate also contributes to mild winters and hot summers, making Key West an aquatic paradise all year.

Best Time to Visit

For the best experience, visit between March and May when water temperatures range from 75-82°F (24-28°C). This period offers clear skies and pleasant weather without the higher humidity and rainfall typical of the summer months. However, if you prefer even warmer waters and don’t mind occasional rain, the summer months (June to August) are also excellent.

Key Insights from Competitors

  • SeaTemperature.org highlights the warmest and coldest months for water temperatures in Key West, with August reaching around 86.5°F (30.3°C) and January dropping to 73.6°F (23.1°C)​.
  • CurrentResults.com provides long-term average temperatures, emphasizing that Key West’s waters are suitable for swimming year-round​​.
  • Sunset Watersports offers a practical month-to-month guide, noting the strategic influence of the Gulf Stream in maintaining warm water temperatures throughout the year​​.


Whether you’re planning a winter escape or a summer adventure, the Florida Keys, particularly Key West, offer warm and inviting waters year-round. Use this guide to choose the best time for your visit and make the most of the stunning aquatic environment.

FAQs About Water Temperature in Key West

1. What is the average water temperature in Key West throughout the year?

The average annual water temperature in Key West is around 79°F (26°C). The temperatures range from a low of about 70°F (21°C) in January to a high of 87°F (31°C) in July and August​​.

2. When is the water warmest in Key West?

The water is warmest in Key West during the summer months of July and August, with temperatures averaging around 87°F (31°C)​​.

3. When is the water coldest in Key West?

The coldest water temperatures in Key West occur in January, with averages around 70°F (21°C)​​.

4. Is the water in Key West warm enough for swimming year-round?

Yes, the water in Key West is warm enough for swimming year-round, even during the coldest months, when temperatures rarely drop below 70°F (21°C)​​.

5. What causes the warm water temperatures in Key West?

The warm water temperatures in Key West are primarily due to its tropical savanna climate and the influence of the Gulf Stream. This warm ocean current helps maintain higher water temperatures throughout the year​.

6. What is the best time to visit Key West for warm water and clear skies?

The best time to visit Key West for warm water and clear skies is between March and May. During these months, water temperatures range from 75-82°F (24-28°C), and the weather is generally pleasant with less humidity and rainfall compared to the summer months​.

7. Are there any safety concerns related to water temperatures in Key West?

Generally, there are no safety concerns related to water temperatures in Key West as the waters remain warm and comfortable for swimming and other activities year-round. However, visitors should always be aware of local weather conditions, especially during hurricane season from June to November​.

8. How do water temperatures in Key West compare to other parts of Florida?

Key West typically has warmer water temperatures compared to many different parts of Florida, especially during the winter months, due to its southernmost location and the influence of the Gulf Stream​​.

9. Can I enjoy water sports in Key West year-round?

Yes, the warm water temperatures in Key West allow for water sports such as snorkeling, diving, kayaking, and paddleboarding to be enjoyed year-round​.

10. How accurate do various sources provide the water temperature measurements?

Water temperature measurements provided by multiple sources are typically based on long-term averages and data collected by organizations such as the National Oceanographic Data Center. These measurements are generally accurate but can vary slightly due to local weather conditions and specific locations within the Key West area​.

Evie Carrick Evie Carrick

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