Month-specific sea-surface temperature · New Zealand

Bay of Islands Sea Temperature in April

20.0°C

68.0°F

In April, sea-surface temperature near Bay of Islands has a historical monthly average of 20.0°C. This is not the reading for any particular holiday date.

Across 2023–2025, the lowest and highest yearly April monthly means were 19.6–20.4°C. These are not daily extremes.

Previous month

March · 21.2°C

Change into April: -1.2°C

Next month

May · 18.7°C

Change into next month: -1.3°C

Can you swim or snorkel in Bay of Islands in April?

At 20.0°C our temperature-only guide describes the water as cool water. Comfort depends on your cold tolerance, immersion time and wind. A historical average cannot determine whether conditions are safe on any given day.

Do you need a wetsuit?

A 3 mm shorty or full wetsuit will make longer snorkels more comfortable.

Which beach should you choose?

Look for a beach sheltered from the actual forecast waves and wind on your visit. Exposure, currents and entry conditions vary even where water temperatures are similar. Follow local warnings.

Check the current waves, wind and snorkeling forecast →

A live forecast does not predict a future April. Check again close to your trip.

Waves and wind: recorded-model conditions for April

These figures come from a separately modelled, date-specific wind/wave backfill, not the NOAA SST series. A single observed season is not a climatological likelihood or a guarantee of safe conditions.

Compare nearby coasts with their own evidence

Coast	Morning	Afternoon	Period
Goat Island	13%	13%	Apr 2026

A “calm hour” meets fixed modelled wave/wind thresholds; neither visibility nor local currents, entry conditions or actual beach safety is measured here. Periods may differ by coast.

Nearby places in April

Comparable historical averages from independent marine grid cells. Warmer water does not imply safe snorkeling.

Poor Knights Islands 20.2°C
Goat Island 19.7°C

Bay of Islands Sea Temperature: All 12 Months

Choose a month for available historical evidence, month comparisons and swim guidance. Missing history is clearly marked and never presented as a long-term normal.

January 20.9°C February 21.8°C March 21.2°C April 20.0°C May 18.7°C June 16.9°C July 15.8°C August 15.3°C September 15.6°C October 15.8°C November 17.7°C December 19.3°C

Data source and limitations

Source: Open-Meteo Marine API, MeteoFrance sea-surface temperature; 2023–2025. Marine model grid near -35.22, 174.09. Based on 3 yearly monthly means and 2160 recorded samples. Source methodology.

Modelled sea-surface temperatures do not establish underwater visibility, wildlife, calm currents or safe entry.