Where the data comes from
This screen brings eleven public sources together in one place: flag services, met agencies, town halls and camera networks. Each of them publishes on its own schedule, so a beach can be current on one line and a few hours old on the next.
Every source below is named, and linked to the page that publishes it - which is where the reading is kept up to date. At the beach itself, the flag on the mast is the one that counts.
What comes from where
How current this is
Flags are re-read every five minutes at most, the model forecast every time a town or a beach is opened, the official one at most every half hour, and a camera shows whatever its operator is publishing right now. The time in the header is when this page last asked.
When the official forecast cannot be fetched at all, a copy read earlier today is shown with the time it was read printed on it. A copy from any other day is thrown away rather than shown: yesterday's tide times are wrong by about fifty minutes.