Apple Weather Kit - Why do past hourly forecast values change?

I am looking at the forecastHourly data for the same latitude and longitude, from 3 days ago at 00:00 to today at 00:00. I noticed that every hour, around the 15th minute, the reportedTime in the forecastHourly metadata changes:

 "readTime": "2023-12-20T07:15:45Z",  -> 2023-12-20T07:21:45Z
 "reportedTime": "2023-12-20T06:00:00Z", -> 2023-12-20T07:01:18Z

The data for the same time in the past (where the value of forecastStart is the same) is different. What is the reason for this?

"readTime": "2023-12-20T07:15:45Z",  -> 2023-12-20T07:21:45Z
"reportedTime": "2023-12-20T06:00:00Z", -> 2023-12-20T07:01:18Z
"forecastStart": "2023-12-18T15:00:00Z",  ===  2023-12-18T15:00:00Z
"humidity": 0.47,  -> 0.46
"temperature": -6.38 -> -6.72
Up vote post of swk-mmm Down vote post of swk-mmm
302 views
Posted by
swk-mmm
Reply
Add a Comment

Replies

Weather station observations may be reported well after the time of the observation, so it is possible for a past forecast to be revised based on new information.

Posted by
Frameworks Engineer
Up vote reply of Frameworks Engineer Down vote reply of Frameworks Engineer
Add a Comment