The idiom "a cold day in July" means that something is very unlikely to happen. It is used to express that something is impossible or highly improbable.
July is typically a hot month in many parts of the world, so the idea of a cold day in July is quite unusual. Therefore, when someone says "it's a cold day in July," they mean that something is unlikely to happen, just like a cold day in July.
For example, if someone says "I think my boss will give me a raise," and you think it's unlikely, you could respond by saying "that'll happen on a cold day in July." This means that you think it's very unlikely to happen.
Overall, the idiom "a cold day in July" is a fun and creative way to express that something is unlikely to happen.
• People say it will be a cold day in July when politicians stop lying to the public.
• A cold day in July is a rare occurrence, but it's not impossible.
• It is a cold day in July, and the weather forecast predicts heavy rain.
• It's a cold day in July, but I'm still going to the beach because I love the sound of the waves.
• Mary promised to go on a picnic with her friends on a cold day in July.
• It will be a cold day in July before I forget your kindness.