Can I pray on snow or wet grass?

The earth is a place of prayer

The Prophet ﷺ said that the earth has been made a place for prayer, so anyone can pray wherever the time of a prayer comes (Sahih al-Bukhari 335). That includes a frosty park in London or a snowy trailhead in Colorado. Allah's Messenger ﷺ did not insist on dry ground either. A Companion reported that it rained until the roof of the mosque leaked, and he saw the Prophet ﷺ prostrating in water and mud, with mud on his forehead (Sahih al-Bukhari 669).

The practical way to do it

• Make a dry layer. Put down a plastic bag or tarp first, then a mat, towel or coat on top.
• Find flat, firm ground. Avoid sheets of ice and deep, loose snow where you cannot stand or prostrate steadily.
• Check for impurity. Avoid dog areas and any snow or grass with visible dirt or waste.
• Pack down snow if you pray on it directly, so your forehead rests on something firm.

Using cloth under your forehead is a long-standing practice. Anas said they used to pray with the Prophet ﷺ and some would place the ends of their clothes at the place of prostration because of the scorching heat (Sahih al-Bukhari 385). If a coat or a scarf helps in the cold, it works in the same way. See Can I pray outside in a park?

Mud and wet clothes

Mud is pure by default, so a muddy jacket or wet trousers do not stop your prayer. Only a visible impurity, such as animal waste mixed in, needs washing. Wet clothes are not impure just because they are wet. See Is mud from the street najis?

When the weather is too harsh

Islam does not ask you to put your health at risk. In a freezing wind or a storm, pray indoors if you can, in a shop doorway, a stairwell, a station waiting room or a parked car. If you are hiking or camping and have no shelter, see How do I pray while hiking or camping?

The same applies to wudu. If water is so cold that it would genuinely harm you, there are allowances. See Can I do tayammum when the water is too cold?