请用json格式回答：明天北京的天气怎么样？
user
```json
{
  "location": "北京",
  "date": "明天",
  "weather": "多云转晴",
  "temperature": {
    "high": 20,
    "low": 10
  },
  "wind": {
    "direction": "北风",
    "speed": "3-4级"
  }
}
```
assistant