27.5 million H3 cells of gridded anomaly are already sitting in Postgres. What is missing is the route out of the VPC — the API runs as a Lambda inside it, because the database is not publicly reachable and should not be.
What lands here
A deck.gl H3HexagonLayer over a MapLibre basemap. grid_monthly maps onto the layer one-to-one, with no geometry conversion in between.
A month scrubber across the full record, and a resolution switch between H3 res 3 and 4 as you zoom.
Cell counts on hover. A cell backed by two stations is drawn as a cell backed by two stations, not as a confident value.
The scale it will use
-3 °Cbaseline+3 °C
Departure from each station’s own 1991–2020 average. Values beyond the ends of the scale clamp — they never wrap around to the opposite colour.