When it updates
A new forecast every day
CAMS computes a new forecast every day, starting from the situation at midnight UTC. Each forecast covers the next 48 hours, hour by hour.
The forecast is guaranteed to be available by 8:00 UTC. Coperni downloads it right after, at 8:30 UTC:
- around 10:30 Central European Summer Time;
- around 9:30 Central European Time (winter).
It takes a few minutes to download and prepare it, then it is immediately visible on the site.
What the map shows
When it opens, the map shows the forecast for the current hour, taken from the most recent forecast: values change at the top of every hour. At the bottom left of the map you will find the day and hour the colours refer to and the date of the forecast used.
With the arrows next to the date you can move by one hour (‹ ›) or one day (« »): forward up to the end of the latest forecast (about two days), back up to 21 days ago. For every hour the most recent forecast covering it is used. The now button takes you back to the current hour.
In the morning, before the update, the map still uses the previous day's forecast (which also covers today): this is normal.
What the charts show
- Past: for each of the last 7 days, the first 24 hours of that day's forecast (the most up-to-date one for every hour).
- Future: the whole latest forecast, up to 48 hours.
What the ranking shows
The ranking compares the most populous places (Italian municipalities above 50,000 inhabitants, other cities above 500,000) using the daily average (00–24 UTC) of the latest forecast, over the same area as the charts (about 150 km around the place). It is recomputed once a day, with the update. Nearby places share most of their area, so their values are often very close.
Forecasts remain available for 21 days, then they are deleted.