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How Far Off Is the Temperature Forecast?

How wrong will the national weather model's temperature forecast for Aarhus be, and in which direction? Correcting the forecast with recent local observations is how forecasters squeeze out extra accuracy.

Use caseClimatePredictionModel evaluation

The table

Forecasts from the Danish Meteorological Institute for Aarhus, with forecast fields, lead time and recent observations, and the error each forecast turned out to have. It's in Welt's research catalogue as DMI Aarhus Weather Data: Training Matrix, 64,568 rows by 76 columns, licensed CC BY 4.0. The catalogue measures its signal at 0.88. At 64,568 rows and 75 features the table is larger than the model limits allow, so the walkthrough evaluates and fits on a seeded sample of 2,000 rows. TabICLv2 and Kumo Tabular Medium compete.

Walkthrough

  1. Load it from the catalogue

    Find the table, read its recorded target and print the column names.

    import pandas as pd
    from welt import Client
    
    with Client() as client:
        item = client.research_datasets(q="DMI Aarhus weather", limit=1)["items"][0]
        info = client.research_dataset(item["id"])
        data = client.load_research_dataset(item["id"])
    
    target = info["targets"][0]
    target = target["name"] if isinstance(target, dict) else target
    print([column["name"] for column in info["schema"]], target)
  2. Pick the rows

    Set aside 20 rows to predict at the end. The models learn from a seeded sample of 2,000 of the rest, the most this table's width allows.

    known = data.dropna(subset=[target])
    new_rows = known.sample(20, random_state=1)
    table = known.drop(new_rows.index).sample(2000, random_state=7)
  3. Compare the models and predict

    The models compete on the same folds against a simple guess, then the top-ranked one is fitted on the whole table. RMSE and MAE are average errors in the target's own units, so lower is better. The last table puts each prediction next to the real answer.

    with Client() as client:
        evaluation = client.evaluate(table, target, task="regression", seed=7,
                                     models=["tabicl-v2", "kumo-medium"])
        model = evaluation.fit()
    
    print(evaluation.summary()[["name", "rank", "rmse_mean", "mae_mean"]])
    features = new_rows.drop(columns=target)
    print(pd.DataFrame({"actual": new_rows[target].values, "predicted": model.predict(features)}))

What you get

A forecast correctionAdd the predicted error to get a better forecast.
Local knowledgeThe model learns where the national forecast goes wrong for one city.
A strong signalThe catalogue measures a high signal for this table.

Try it

Use Open with to run the research datasets notebook in Colab, Kaggle or Jupyter and search for "DMI Aarhus weather", or run the code above after pip install "welt-client[parquet]".