---
id: questions/weather-and-climate
about:
  label: Weather and climate
  description: >-
    What weather is coming this week, and how will the climate of this place
    change over decades?
question: {}
domains:
  - climate
provenance:
  origin: agent
  reviewed: '2026-10-18'
  reviewed_by: >-
    Claude, written for the patrons in devlog/20261018-patrons.md from entries
    on this site; not yet read by Anselm
  status: draft
---
Two questions people ask in the same breath, answered by different models at different scales. The one you need depends on whether you are planning a weekend or a seawall.

## What you are really asking

- **The forecast**: what will happen in the next hours to two weeks. Global weather models answer it, and you almost never need to run one yourself.
- **The projection**: how temperature, rain, sea level and extremes shift over the coming decades under a given emissions path. Climate models answer it, at a coarse grid, and the work in a local study is in bringing the result down to your place.
- **The local picture**: how hot a particular street gets on a summer afternoon, which depends on buildings, trees and surfaces as much as on the regional climate. That is urban microclimate modelling, and it is where a neighbourhood question lives.

## What kind of model answers it

Weather and climate models solve the physics of the atmosphere on a grid. The newest ones learn from decades of past weather instead and run far faster; the entries on this site for [AIFS](/engines/aifs/) from ECMWF and [Aurora](/engines/aurora/) from Microsoft Research describe two that are open. [Destination Earth](/engines/destination-earth/) is the European programme building climate and extremes twins at continental scale, and [WeatherNext and NVIDIA Earth-2](/engines/weathernext-nvidia-earth-2/) are two commercial routes to the same kind of forecast.

For the street-level question, [friGIS](/engines/frigis/) is a hosted tool that puts a microclimate model behind a planning editor for trees, surfaces and water. Open tools exist for the same job and are not yet on this site.

## What you need

- For projections: the published climate scenarios for your region, which your national weather service or a university will have downscaled already.
- For the local picture: buildings, tree canopy and surface types for your area, and summer temperature observations to check against. The [New York tree map](/data-sources/cornell-nyc-individual-tree-map/) is an example of what a city-wide tree dataset looks like.
- A record of what has already happened: [Climate Reanalyzer](/data-sources/climate-reanalyzer/) shows the global and regional series, and [Vitals](/vitals/) on this site tracks six of them.

## Without a model

Read your region's published climate projection and the last three summers' temperature record. For a heat question, go out at four in the afternoon with a thermometer and walk from a treed street to a bare one. The difference you measure is the thing the model is for.

## Next

[Choose the kind of model](/guides/choose-the-kind-of-model/).