Best time of year to snorkel at the Great Barrier Reef?

As Power Flower said, May and September are both good. Between October and April (roughly - depending on how far north you intend to snorkel), Box and Irukandji Jellyfish make it hard. And the temperatures are uncomfortably hot too. And between June and August the waters in southern parts of the GBR are too cool. Went snorkelling around Heron Island in July and the water was so cold i needed a warm wetsuit.

The ocean waters are becoming warmer; consequently the box jelly are appearing on Australia's coastline farther south and for longer times. A few years ago, the jelly fish were gone from the end of April through September; now they appear in the far north through June.

The Great Barrier Reef stretches from north of Brisbane beyond Cairns on Australia's east coast. Other than from a very few barrier islands with resorts, you must take a boat to snorkel on the reef. The boats tend to dock on permanent pontoons over the reef where the jelly fish are not present (the jelly fish prefer shallow water and are closer to the coastline). Some other boats visit small cays in the reef for a day of snorkeling and diving; others are overnight boats that go to sites farther out on the reef.

The region in Australia where you will find the best selection of day trips to the reef is between Cairns and Port Douglas in the tropical north (this is the region where the jelly fish will also be present for the longest time). The temperatures in tropical north Queensland tend to be in the high 80s by day and slightly cooler by night in May and September. The ocean water is warm and you'll have mostly sunshine (the "rainy" season is late-October to March, when the air becomes extremely humid).

In May and September, regions in Australia along the southern coast - Adelaide, Melbourne, Tasmania - that you might want to include in your visit will be cooler, but great for sightseeing and walks.

In the summer time is the best time to snorkel at the Great Barrier Reef.I would say May would be better I have been to the Great Barrier Reef a couple of years ago in may and it was very nice when I went but I went diving and that was beautiful.So again I would say May would be better

The best time is the cooler months, between April and November. You will be able to swim safely, and there will be no threat of cyclones. The weather along the entire Great Barrier Reef will still be warm, but the further north you go the hotter it will be.

Either is fine.

This was asked in the US forum initially so I will use the US as a comparison.

If you are from Florida or California, you may find the weather cool but not unpleasant. If you're from anywhere that snows you will find it more than pleasant...

We work in degrees celsius.

15 degrees celsius = 60 degrees fahrenheit

20 = 70

25 = 77

30 = 85

Perfect! Summer is incredibly hot and humid and uncomfortable...... not to mention wet and the stingers. May or Sept should be a bit milder and nicer - especially as you won't spend all your time in the water! It doesn't get cold up there so you'll be fine.