USA · Key Largo
Best Time to Dive in Key Largo, Florida Keys
25.01°N 80.38°W
Go August to September for goliath grouper. 22% of years see a tropical storm pass within 250 km then — March to July is calmer, but the animals have gone. The full season runs February to July.
- Best time
- Aug–Sep
- Water
- 24–31 °C
- Visibility
- 15–30 m
- Season runs
- Feb–Jul
- Dived from
- day boat and shore diving
- Tidal range
- 0.5–0.8 m
- Species logged
- 15
Worth knowing: 22% of years see a tropical storm pass within 250 km.
Where it is
111 km across · coastline from Natural Earth 10m
Diving in Key Largo, Florida Keys — monthly breakdown
A year of scuba diving conditions at a glance. Hover a month to isolate it.
| January | February | March | April | May | June | July | August | September | October | November | December | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Conditions | Poor | Poor | Poor | Poor | Poor | Poor | Poor | Excellent | Excellent | Poor | Poor | Poor |
| Water temp (°C) | 24 | 25 | 25 | 26 | 28 | 29 | 30 | 31 | 30 | 29 | 27 | 25 |
| Visibility (m) | 15–25 | 20–30 | 20–30 | 20–30 | 20–30 | 20–30 | 20–30 | 20–30 | 15–25 | 15–25 | 20–30 | 20–30 |
| Marine life | Steady | Steady | Steady | Steady | Steady | Steady | Steady | Peak | Peak | Steady | Steady | Steady |
| Best time | Peak | Peak |
Excellent Good Moderate PoorPeak season Aug–Sep
Long-term averages, 2016–2025. Visibility is estimated from satellite chlorophyll-a. Water temperature is the surface mean; it is cooler at depth.
The Key Largo, Florida Keys diving season
August to September · Peak season
2 monthsJFMAMJJASOND
- Water temperature
- 30–31 °C
- Visibility
- 20–30 m
- Rain
- 18 days a month
Diving conditionsIt rains more. The sea is calmer.
Marine lifeGoliath grouper (near-guaranteed) peaks at Key Largo, Florida Keys in these months.
October to July · Off season
10 monthsJFMAMJJASOND
- Water temperature
- 24–30 °C
- Visibility
- 20–30 m
- Rain
- 10 days a month
Diving conditionsThe sea is rougher. The wind is up.
Marine lifeGoliath grouper (near-guaranteed), Great hammerhead (hit-or-miss) peak at Key Largo, Florida Keys in these months.
- Water temperature is satellite sea-surface temperature, so expect it cooler below the thermocline.
- Visibility is estimated from satellite chlorophyll-a.
Florida Keys water temperature and weather
5,648 underwater observation records · 32 surveyed years of ocean data · 10 years of sea temperature
Water & weather
Key Largo, Florida Keys water temperature by month
The dashed line is the monthly average. Eight days in ten fall inside the band.
10th to 90th percentile rangemonthly mean
3
rough days a month
Seas top 1.5 m on 9% of days. Enough to cancel a day boat
2
blowy days a month
Gusts over 40 km/h, about where a day boat stays in port
11
wet days a month
2 of them bring heavy rain
| Month | Swell | Gusts over 40 km/h | Wet days | Heavy rain | Air | Daylight |
|---|---|---|---|---|---|---|
| January | 1.4 m | 14% | 7 | 2 | 24 °C | 10.6 h |
| February | 1.4 m | 9% | 6 | 1 | 24 °C | 11.2 h |
| March | 1.6 m | 10% | 5 | 1 | 25 °C | 11.8 h |
| April | 1.6 m | 4% | 7 | 2 | 26 °C | 12.6 h |
| May | 1.1 m | 4% | 11 | 3 | 27 °C | 13.2 h |
| June | 1.1 m | 1% | 17 | 4 | 29 °C | 13.5 h |
| July | 1.0 m | 0% | 16 | 2 | 30 °C | 13.4 h |
| August | 1.1 m | 2% | 18 | 3 | 30 °C | 12.9 h |
| September | 1.0 m | 6% | 19 | 4 | 29 °C | 12.1 h |
| October | 1.6 m | 8% | 16 | 4 | 28 °C | 11.4 h |
| November | 1.7 m | 12% | 10 | 2 | 26 °C | 10.8 h |
| December | 1.7 m | 12% | 8 | 2 | 25 °C | 10.5 h |
Swell is the rough end of the month: nine days in ten come in under it. Sea temperature covers 10 years, waves 4.
Pick your week
48 weeks from the daily record. Darker is better, against this site's own year. Pick a month for the detail.
| Week 1 | January week 1: Poor | February week 1: Poor | March week 1: Poor | April week 1: Poor | May week 1: Poor | June week 1: Poor | July week 1: Poor | August week 1: Good | September week 1: Excellent | October week 1: Moderate | November week 1: Moderate | December week 1: Poor |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Week 2 | January week 2: Poor | February week 2: Poor | March week 2: Poor | April week 2: Poor | May week 2: Poor | June week 2: Poor | July week 2: Poor | August week 2: Good | September week 2: Good | October week 2: Poor | November week 2: Moderate | December week 2: Poor |
| Week 3 | January week 3: Poor | February week 3: Poor | March week 3: Poor | April week 3: Poor | May week 3: Poor | June week 3: Poor | July week 3: Poor | August week 3: Good | September week 3: Good | October week 3: Moderate | November week 3: Poor | December week 3: Moderate |
| Week 4 | January week 4: Poor | February week 4: Poor | March week 4: Poor | April week 4: Poor | May week 4: Poor | June week 4: Poor | July week 4: Poor | August week 4: Excellent | September week 4: Excellent | October week 4: Moderate | November week 4: Poor | December week 4: Poor |
Excellent Good Moderate PoorBest week to go: fourth of August
January, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 25 °C | 1.3 m | 29 km/h | 23% |
| Week 2 | Poor | 24 °C | 1.4 m | 31 km/h | 27% |
| Week 3 | Poor | 24 °C | 1.5 m | 31 km/h | 24% |
| Week 4 | Poor | 24 °C | 1.6 m | 30 km/h | 20% |
February, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 24 °C | 1.5 m | 29 km/h | 17% |
| Week 2 | Poor | 24 °C | 1.5 m | 29 km/h | 18% |
| Week 3 | Poor | 25 °C | 1.4 m | 29 km/h | 22% |
| Week 4 | Poor | 25 °C | 1.3 m | 28 km/h | 19% |
March, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 25 °C | 1.2 m | 29 km/h | 12% |
| Week 2 | Poor | 25 °C | 1.5 m | 29 km/h | 14% |
| Week 3 | Poor | 25 °C | 1.6 m | 29 km/h | 19% |
| Week 4 | Poor | 25 °C | 1.7 m | 28 km/h | 17% |
April, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 26 °C | 1.7 m | 28 km/h | 19% |
| Week 2 | Poor | 26 °C | 1.5 m | 29 km/h | 23% |
| Week 3 | Poor | 26 °C | 1.5 m | 29 km/h | 24% |
| Week 4 | Poor | 27 °C | 1.6 m | 28 km/h | 25% |
May, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 27 °C | 1.3 m | 27 km/h | 26% |
| Week 2 | Poor | 27 °C | 1.2 m | 26 km/h | 35% |
| Week 3 | Poor | 28 °C | 1.1 m | 25 km/h | 41% |
| Week 4 | Poor | 28 °C | 1.2 m | 24 km/h | 39% |
June, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 29 °C | 1.2 m | 24 km/h | 51% |
| Week 2 | Poor | 29 °C | 1.1 m | 24 km/h | 61% |
| Week 3 | Poor | 29 °C | 1.1 m | 22 km/h | 55% |
| Week 4 | Poor | 29 °C | 1.0 m | 21 km/h | 51% |
July, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 30 °C | 0.9 m | 20 km/h | 48% |
| Week 2 | Poor | 30 °C | 0.9 m | 21 km/h | 48% |
| Week 3 | Poor | 30 °C | 1.0 m | 22 km/h | 52% |
| Week 4 | Poor | 30 °C | 1.1 m | 22 km/h | 55% |
August, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Good | 30 °C | 1.1 m | 22 km/h | 54% |
| Week 2 | Good | 31 °C | 1.0 m | 21 km/h | 50% |
| Week 3 | Good | 31 °C | 1.0 m | 22 km/h | 55% |
| Week 4 | Excellent | 30 °C | 1.1 m | 23 km/h | 67% |
September, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 30 °C | 1.0 m | 23 km/h | 66% |
| Week 2 | Good | 30 °C | 0.8 m | 20 km/h | 61% |
| Week 3 | Good | 30 °C | 0.8 m | 20 km/h | 63% |
| Week 4 | Excellent | 30 °C | 1.4 m | 23 km/h | 63% |
October, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 29 °C | 1.6 m | 26 km/h | 60% |
| Week 2 | Poor | 29 °C | 1.2 m | 27 km/h | 58% |
| Week 3 | Moderate | 29 °C | 1.5 m | 29 km/h | 50% |
| Week 4 | Moderate | 28 °C | 1.8 m | 30 km/h | 40% |
November, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 27 °C | 1.9 m | 30 km/h | 38% |
| Week 2 | Moderate | 27 °C | 1.9 m | 29 km/h | 38% |
| Week 3 | Poor | 27 °C | 1.4 m | 27 km/h | 32% |
| Week 4 | Poor | 26 °C | 1.4 m | 27 km/h | 23% |
December, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 26 °C | 1.4 m | 27 km/h | 18% |
| Week 2 | Poor | 26 °C | 2.0 m | 29 km/h | 27% |
| Week 3 | Moderate | 25 °C | 2.0 m | 30 km/h | 31% |
| Week 4 | Poor | 25 °C | 1.6 m | 29 km/h | 24% |
10 years of daily records, averaged into weeks.
Gear & storms
What to wear
Off the coldest water of each month, not the average — that is what the suit has to cope with.
| January | February | March | April | May | June | July | August | September | October | November | December | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Suit | January: 5 mm | February: 5 mm | March: 3 mm | April: 3 mm | May: 3 mm | June: skin | July: skin | August: skin | September: skin | October: skin | November: 3 mm | December: 5 mm |
- Dec–Feb5 mm full suit
- Mar–May3 mm full suit
- Jun–Octskin or 3 mm shorty
- Nov3 mm full suit
Swell through the year
The rough end of each month — nine days in ten come in under it.
Amber is over 1.5 m.
Tides
Tropical storms
7 of the last 30 Septembers saw a tropical storm pass within 250 km. Anything has been recorded Jul–Nov.
Share of the last 30 years with a storm that month.
- NOAASea surface temperature, from OISST and MUR
- ERA5Wind, waves, rain and air temperature, via Open-Meteo
- OBISMarine species records within 60 km
- IBTrACSTropical cyclone tracks, 1996 to 2025
Key Largo, Florida Keys marine life — what you'll see diving
| Species | When | Observed window | Reliability | Evidence | Records |
|---|---|---|---|---|---|
| Manatee | Jan–Feb | Near-guaranteed | 2183 | ||
| Nurse shark | All year | Near-guaranteed | 668 | ||
| Southern stingray | Feb–Apr | Near-guaranteed | 597 | ||
| Nassau grouper | Jun–Aug | Near-guaranteed | 208 | ||
| Spotted eagle ray | All year | Near-guaranteed | 141 | ||
| Bottlenose dolphin | Jan–Mar | Near-guaranteed | 921 | ||
| Goliath grouper | All year | Near-guaranteed | 204 | ||
| Green turtle | Dec–Feb | Likely | 120 | ||
| Lemon shark | Feb, Apr | Hit-or-miss | 189 | ||
| Bull shark | Mar | Hit-or-miss | 58 | ||
| Silky shark | Feb | Hit-or-miss | 20 | ||
| Loggerhead turtle | Apr, Jun, Dec | Likely | 76 | ||
| Great hammerhead | Feb | Hit-or-miss | 8 | ||
| Yellowfin tuna | Jan–Feb, May | Hit-or-miss | 148 | ||
| Hawksbill turtle | Feb–Mar, May, Nov | Likely | 19 |
Peak Present No survey data
- Observed window
- Months with records. Peak is where most of them fall.
- Reliability
- Near-guaranteed in 60% of surveyed years or more
- Likely 30% to 60%
- Hit-or-miss under 30%
- Evidence
- Years it was seen, out of the years anyone surveyed.
- Records
- OBIS sightings within 60 km.
These are sightings people logged, not a full survey of the reef. A species missing from a month may just mean nobody recorded one.
Diving Key Largo, Florida Keys — common questions
- When is the best time to dive Key Largo, Florida Keys?
- Go August to September for goliath grouper. 22% of years see a tropical storm pass within 250 km then — March to July is calmer, but the animals have gone. The full season runs February to July.
- When is the diving season in Key Largo, Florida Keys?
- Conditions are good February to July, but most divers come August to September for the marine life.
- Is the diving in Key Largo, Florida Keys good for beginners?
- Yes. It suits Open Water divers, so it works for a first trip after certification.
- How warm is the water in Key Largo, Florida Keys?
- Between 24 and 31 °C at the surface across the year, coldest in January and warmest in August. It runs cooler below the thermocline.
- What wetsuit do I need in Key Largo, Florida Keys?
- A 5 mm full suit covers the coldest water of the year. In the warmest months a skin or 3 mm shorty is enough.
- What is the visibility like in Key Largo, Florida Keys?
- Roughly 15 to 30 m depending on the month. That is estimated from satellite chlorophyll-a rather than measured in the water.
- What will I see diving Key Largo, Florida Keys?
- The most consistently recorded species are Manatee (near-guaranteed), Nurse shark (near-guaranteed) and Southern stingray (near-guaranteed), from 5,648 records within 60 km.
- Does Key Largo, Florida Keys get tropical storms?
- Yes. Over 30 years of records a storm passed within 250 km in Jul–Nov, most often in September at 7 of 30 years.
- Is there current in Key Largo, Florida Keys?
- The tide rises and falls 0.8 m around the full and new moon, against 0.5 m in between. How much of that becomes current depends on the shape of the channel.
- When should I avoid Key Largo, Florida Keys?
- October–July are the weakest months for conditions.
- How do you dive Key Largo, Florida Keys?
- Mostly from day boats and the shore. Trips run through the season, Feb–Jul.