Best Time to Dive in Catalina Island
Plan for June to October once the water has warmed to 20 °C from 16. The marine life holds steady all year, so the weather picks the month.
- Best time
- Jun–Oct
- Water
- 15–21 °C
- Visibility
- 15–30 m
- Dived from
- shore diving and day boat
- Tidal range
- 1.1–2.2 m
- Species logged
- 17
Worth knowing: 39% of days see seas over 1 m.
Where it is
111 km across · coastline from Natural Earth 10m
Diving in Catalina Island — 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 | Moderate | Excellent | Excellent | Excellent | Excellent | Excellent | Moderate | Poor |
| Water temp (°C) | 15 | 15 | 15 | 16 | 17 | 19 | 20 | 21 | 21 | 20 | 18 | 16 |
| Visibility (m) | 15–25 | 15–25 | 15–25 | 15–25 | 15–25 | 15–25 | 15–25 | 15–25 | 15–25 | 15–25 | 20–30 | 15–25 |
| Marine life | Peak | Peak | Peak | Peak | Peak | Peak | Peak | Peak | Peak | Peak | Peak | Peak |
| Best time | Peak | Peak | Peak | Peak | Peak |
Long-term averages, 2016–2025. Visibility is estimated from satellite chlorophyll-a. Water temperature is the surface mean; it is cooler at depth.
The Catalina Island diving season
May · Shoulder season
1 month- Water temperature
- 17–17 °C
- Visibility
- 15–25 m
- Rain
- 2 days a month
Diving conditionsIt rains less. The sea is rougher.
Marine lifeCalifornia sea lion (near-guaranteed), Sardine (near-guaranteed), Ocean sunfish (near-guaranteed) peak at Catalina Island in these months.
June to October · Peak season
5 months- Water temperature
- 19–21 °C
- Visibility
- 15–25 m
- Rain
- 1 days a month
Diving conditionsSeas stay mostly calm. The wind eases. It rains less.
Marine lifeCalifornia sea lion (near-guaranteed), Sardine (near-guaranteed), Ocean sunfish (near-guaranteed), Shortfin mako (likely) peak at Catalina Island in these months.
November · Shoulder season
1 month- Water temperature
- 18–18 °C
- Visibility
- 20–30 m
- Rain
- 3 days a month
Diving conditionsSeas stay mostly calm.
Marine lifeCalifornia sea lion (near-guaranteed), Sardine (near-guaranteed), Ocean sunfish (near-guaranteed), Blue shark (likely) peak at Catalina Island in these months.
December to April · Off season
5 months- Water temperature
- 15–16 °C
- Visibility
- 15–25 m
- Rain
- 5 days a month
Diving conditionsExpect some swell. The wind is up. It rains more.
Marine lifeCalifornia sea lion (near-guaranteed), Sardine (near-guaranteed), Ocean sunfish (near-guaranteed), Blue shark (likely) peak at Catalina Island in these months.
- Spring tides run 2.2 m against 1.1 m on neaps, so currents build around the full and new moon.
- Water temperature is satellite sea-surface temperature, so expect it cooler below the thermocline.
- Visibility is estimated from satellite chlorophyll-a.
Catalina Island water temperature and weather
9,149 underwater observation records · 32 surveyed years of ocean data · 10 years of sea temperature
Water & weather
Catalina Island 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
Seas top 1.0 m on 39% of days. Enough to cancel a shore entry
Gusts over 40 km/h, about where a day boat stays in port
1 of them bring heavy rain
| Month | Swell | Gusts over 40 km/h | Wet days | Heavy rain | Air | Daylight |
|---|---|---|---|---|---|---|
| January | 1.9 m | 5% | 6 | 2 | 17 °C | 10.0 h |
| February | 2.0 m | 5% | 5 | 1 | 17 °C | 10.8 h |
| March | 2.0 m | 7% | 7 | 1 | 17 °C | 11.8 h |
| April | 1.6 m | 3% | 2 | 0 | 18 °C | 12.8 h |
| May | 1.4 m | 1% | 2 | 0 | 19 °C | 13.7 h |
| June | 1.2 m | 0% | 1 | 0 | 21 °C | 14.2 h |
| July | 1.0 m | 0% | 0 | 0 | 22 °C | 14.0 h |
| August | 1.1 m | 0% | 1 | 0 | 24 °C | 13.2 h |
| September | 1.2 m | 0% | 2 | 0 | 24 °C | 12.2 h |
| October | 1.3 m | 1% | 2 | 0 | 23 °C | 11.1 h |
| November | 1.4 m | 2% | 3 | 1 | 20 °C | 10.2 h |
| December | 1.6 m | 3% | 5 | 2 | 18 °C | 9.8 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: Excellent | July week 1: Excellent | August week 1: Excellent | September week 1: Excellent | October week 1: Excellent | November week 1: Moderate | December week 1: Moderate |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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: Excellent | July week 2: Excellent | August week 2: Excellent | September week 2: Excellent | October week 2: Excellent | November week 2: Poor | December week 2: Moderate |
| Week 3 | January week 3: Poor | February week 3: Poor | March week 3: Poor | April week 3: Moderate | May week 3: Moderate | June week 3: Excellent | July week 3: Excellent | August week 3: Excellent | September week 3: Excellent | October week 3: Excellent | November week 3: Moderate | December week 3: Poor |
| Week 4 | January week 4: Moderate | February week 4: Poor | March week 4: Poor | April week 4: Moderate | May week 4: Good | June week 4: Excellent | July week 4: Excellent | August week 4: Excellent | September week 4: Excellent | October week 4: Good | November week 4: Good | December week 4: Poor |
January, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 16 °C | 2.2 m | 18 km/h | 21% |
| Week 2 | Poor | 15 °C | 2.1 m | 17 km/h | 20% |
| Week 3 | Poor | 15 °C | 1.6 m | 17 km/h | 19% |
| Week 4 | Moderate | 15 °C | 1.5 m | 18 km/h | 17% |
February, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 15 °C | 1.8 m | 18 km/h | 18% |
| Week 2 | Poor | 15 °C | 2.0 m | 18 km/h | 16% |
| Week 3 | Poor | 15 °C | 2.1 m | 20 km/h | 14% |
| Week 4 | Poor | 15 °C | 2.2 m | 20 km/h | 20% |
March, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 15 °C | 2.1 m | 21 km/h | 26% |
| Week 2 | Poor | 15 °C | 1.9 m | 22 km/h | 28% |
| Week 3 | Poor | 15 °C | 2.0 m | 22 km/h | 22% |
| Week 4 | Poor | 15 °C | 2.0 m | 22 km/h | 14% |
April, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 15 °C | 2.0 m | 21 km/h | 13% |
| Week 2 | Poor | 16 °C | 1.7 m | 21 km/h | 11% |
| Week 3 | Moderate | 16 °C | 1.5 m | 22 km/h | 6% |
| Week 4 | Moderate | 16 °C | 1.4 m | 22 km/h | 6% |
May, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 17 °C | 1.5 m | 21 km/h | 7% |
| Week 2 | Poor | 17 °C | 1.5 m | 21 km/h | 6% |
| Week 3 | Moderate | 17 °C | 1.3 m | 21 km/h | 6% |
| Week 4 | Good | 17 °C | 1.1 m | 20 km/h | 6% |
June, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 18 °C | 1.1 m | 19 km/h | 6% |
| Week 2 | Excellent | 18 °C | 1.2 m | 19 km/h | 4% |
| Week 3 | Excellent | 19 °C | 1.2 m | 20 km/h | 2% |
| Week 4 | Excellent | 19 °C | 1.2 m | 19 km/h | 1% |
July, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 20 °C | 1.1 m | 19 km/h | 0% |
| Week 2 | Excellent | 20 °C | 1.0 m | 19 km/h | 0% |
| Week 3 | Excellent | 21 °C | 1.0 m | 19 km/h | 0% |
| Week 4 | Excellent | 21 °C | 1.1 m | 20 km/h | 1% |
August, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 21 °C | 1.2 m | 20 km/h | 2% |
| Week 2 | Excellent | 21 °C | 1.1 m | 20 km/h | 2% |
| Week 3 | Excellent | 21 °C | 1.1 m | 20 km/h | 2% |
| Week 4 | Excellent | 22 °C | 1.0 m | 20 km/h | 2% |
September, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 22 °C | 1.1 m | 20 km/h | 3% |
| Week 2 | Excellent | 21 °C | 1.2 m | 20 km/h | 6% |
| Week 3 | Excellent | 21 °C | 1.1 m | 20 km/h | 6% |
| Week 4 | Excellent | 21 °C | 1.1 m | 19 km/h | 5% |
October, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 20 °C | 1.2 m | 18 km/h | 5% |
| Week 2 | Excellent | 20 °C | 1.3 m | 18 km/h | 5% |
| Week 3 | Excellent | 20 °C | 1.3 m | 18 km/h | 5% |
| Week 4 | Good | 19 °C | 1.5 m | 17 km/h | 4% |
November, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 19 °C | 1.6 m | 17 km/h | 5% |
| Week 2 | Poor | 18 °C | 1.5 m | 17 km/h | 9% |
| Week 3 | Moderate | 18 °C | 1.4 m | 17 km/h | 11% |
| Week 4 | Good | 17 °C | 1.2 m | 16 km/h | 11% |
December, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 17 °C | 1.2 m | 15 km/h | 11% |
| Week 2 | Moderate | 17 °C | 1.3 m | 15 km/h | 9% |
| Week 3 | Poor | 16 °C | 1.6 m | 16 km/h | 13% |
| Week 4 | Poor | 16 °C | 1.9 m | 18 km/h | 22% |
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: 7 mm | February: 7 mm | March: 7 mm | April: 7 mm | May: 7 mm | June: 5 mm + | July: 5 mm + | August: 5 mm + | September: 5 mm + | October: 5 mm + | November: 7 mm | December: 7 mm |
- Nov–May7 mm semi-dry
- Jun–Oct5 mm with hood and gloves
Swell through the year
The rough end of each month — nine days in ten come in under it.
Amber is over 1.0 m.
Tides
Tropical storms
No tropical storm has come within 250 km in 30 years of records. Swell and wind set the season, not cyclones.
- 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
Catalina Island marine life — what you'll see diving
| Species | When | Observed window | Reliability | Evidence | Records |
|---|---|---|---|---|---|
| California sea lion | All year | Near-guaranteed | 1765 | ||
| Sardine | All year | Near-guaranteed | 848 | ||
| Common dolphin | All year | Near-guaranteed | 1075 | ||
| Bottlenose dolphin | All year | Near-guaranteed | 635 | ||
| Ocean sunfish | All year | Near-guaranteed | 151 | ||
| Humpback whale | All year | Near-guaranteed | 2574 | ||
| Blue whale | May–Jul | Near-guaranteed | 366 | ||
| Grey whale | Feb–Mar | Near-guaranteed | 784 | ||
| Minke whale | All year | Near-guaranteed | 124 | ||
| Harbour seal | All year | Likely | 327 | ||
| Green turtle | All year | Likely | 151 | ||
| Shortfin mako | Jun–Jul | Likely | 42 | ||
| Orca | Dec–Jan | Likely | 166 | ||
| Bryde's whale | Sep | Hit-or-miss | 9 | ||
| Blue shark | Jan, Jul, Nov | Likely | 58 | ||
| Sperm whale | Dec–Jan, Jun | Hit-or-miss | 31 | ||
| Common thresher | Apr, Nov | Hit-or-miss | 27 |
- 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 Catalina Island — common questions
- When is the best time to dive Catalina Island?
- Plan for June to October once the water has warmed to 20 °C from 16. The marine life holds steady all year, so the weather picks the month.
- When is the diving season in Catalina Island?
- The diving season in Catalina Island runs June to October.
- Is the diving in Catalina Island good for beginners?
- Yes. It suits Open Water divers, so it works for a first trip after certification.
- How warm is the water in Catalina Island?
- Between 15 and 21 °C at the surface across the year, coldest in February and warmest in August. It runs cooler below the thermocline.
- What wetsuit do I need in Catalina Island?
- A 7 mm semi-dry covers the coldest water of the year. In the warmest months a 5 mm with hood and gloves is enough.
- What is the visibility like in Catalina Island?
- 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 Catalina Island?
- The most consistently recorded species are California sea lion (near-guaranteed), Sardine (near-guaranteed) and Common dolphin (near-guaranteed), from 9,149 records within 60 km.
- Does Catalina Island get tropical storms?
- No. None has passed within 250 km in 30 years of records.
- Is there current in Catalina Island?
- The tide rises and falls 2.2 m around the full and new moon, against 1.1 m in between. How much of that becomes current depends on the shape of the channel.
- When should I avoid Catalina Island?
- January–March are the weakest months for conditions.
- How do you dive Catalina Island?
- Mostly from the shore and day boats. Trips run through the season, Jun–Oct.