The cone of cold spell description states:

A blast of cold air erupts from your hands. Each creature in a 60-foot cone must make a Constitution saving throw. A creature takes 8d8 cold damage on a failed save, or half as much damage on a successful one.

A creature killed by this spell becomes a frozen statue until it thaws.

Say a 10th-level Sorcerer standing on dry land casts cone of cold on a creature in water 10 feet ahead of the spellcaster. Assume the creature is not killed.

Does the water freeze? The spell description doesn't refer to any environmental effects.

Cone of Cold does not freeze water

You already gave the reason yourself:

The spell description doesn't refer to any environmental effects.

And since spells only do what they say, then we know that by RAW, Cone of Cold does not freeze water. Any other behaviour of the spell is entirely up to the DM.

Contrast this with Fireball, which does mention environmental effects (emphasis mine):

The fire spreads around corners. It ignites flammable objects in the area that aren't being worn or carried.

A spell that does freeze water is Freezing Sphere (thanks to @RyanThompson), which says:

If the globe strikes a body of water of a liquid that is principally water (not including water-based creatures), it freezes the liquid to a depth of 6 inches over an area of 30 feet square. [...]

Cone of Cold does not have similar wording and does not freeze water within the range.

Several people, including Pierre Cathe's answer have mentioned that the spell description does contain one environmental effect description:

A blast of cold air erupts from your hands.

The argument is that this could be used to justify a homebrew ruling where Cone of Cold does freeze water. Personally I would not rule this way and here are some of the points I think need to be considered:

• 'Blast' and 'cold' are not game terms. We have no context for their meaning or severity. A blast of cold air to one person could be a "a cool breeze" to another as these terms, without definition, are entirely subjective.


• Allowing this spell to freeze water gives it one of the benefits of the higher level spell Freezing Sphere.


• If it freezes water then it poses issues with underwater combat, line of effect through water and potential difficult terrain.

Overall I think it isn't a good house-rule. Under 'rule of cool' (pun intended) I may allow it once but certainly wouldn't rule this way consistently.

It is subject to GM interpretation

The spell doesn't say that it freezes water. However, it does refer to environmental effects. Specifically it says that it creates

A blast of cold air

As there is no fluff/flavor text in 5e spells, this blast of air must be actually happening.

This could reasonably be ruled to freeze some water since it is a 5th-level blast of cold air, though the amount and thickness of the ice are up to GM discretion.

As @Pyrotechnical pointed out in the comments, the spell mentions that

A creature killed by this spell becomes a frozen statue until it thaws.

Which should require some pretty intense cold. While not a RAW justification, it does imply that the water in the creatures is frozen, so logically it should be the same for water outside of creatures.

Personal experience

This happened to me in a game where the players were fighting monsters on the other side of a pond. One of them wanted to cast cone of cold to freeze the pond and allow the fighter to get to the other side faster so I allowed it and described it as (roughly) :

Biting cold air escapes from your outstreched hands towards the pond and the enemies, leaving a layer of frost on the ground and instantly freezing the water.

Then I had the fighter do a DEX check to avoid slipping and shattering the ice, which royally failed, hilarity ensued.