Returns Historical Observations - Given a City ID

{
  "type": "object",
  "properties": {
    "callback": {
      "type": "string"
    },
    "city_id": {
      "type": "string"
    },
    "end_date": {
      "type": "string"
    },
    "key": {
      "type": "string"
    },
    "lang": {
      "type": "string"
    },
    "start_date": {
      "type": "string"
    },
    "units": {
      "type": "string"
    }
  },
  "required": [
    "city_id",
    "end_date",
    "key",
    "start_date"
  ],
  "additionalProperties": false
}