foundation-forecasting

Foundation Model Forecasting (Zero-Shot)

References

See references/adapter-parameters.md for the per-adapter constructor parameters of ChronosAdapter, TimesFMAdapter, MoiraiAdapter, TabICLAdapter, TabPFNAdapter, and T0Adapter.

When to Use

Use ForecasterFoundation when:

• You want a zero-shot baseline before investing in model training.
• You have very short histories where ML models struggle.
• You need to forecast cold-start series (new product, new sensor).
• You want to compare against pre-trained generalist models.

Foundation models are pre-trained on massive corpora — fit() does not train them; it only stores the recent context and metadata.

Stop Conditions

Scan before writing code. Each row lists a rule, the symptom when it is broken, and the recovery. Full pitfall catalog: the troubleshooting-common-errors skill.

Installation

Foundation model backends are not bundled with skforecast. Install only the backend(s) you need:

pip install chronos-forecasting                                 # For Chronos-2
pip install git+https://github.com/google-research/timesfm.git  # For TimesFM 2.5
pip install uni2ts                                              # For Moirai-2
pip install tabicl[forecast]                                    # For TabICL
pip install tabpfn-time-series                                  # For TabPFN-TSpip install tfc-t0                                             # For T0```

Models are downloaded from HuggingFace on first use.

## Quick Start (single series)

```python
import pandas as pd
from skforecast.foundation import FoundationModel, ForecasterFoundation

# Data must have a DatetimeIndex with a frequency
data = pd.read_csv('data.csv', index_col='date', parse_dates=True).asfreq('h')

# 1. Configure a foundation model (adapter is resolved from model_id)
model = FoundationModel(
    model_id='autogluon/chronos-2-small',
    context_length=2048,      # Adapter-specific default: see reference
    device_map='auto',        # 'auto' picks CUDA > MPS > CPU
)

# 2. Wrap it in ForecasterFoundation for the skforecast API
forecaster = ForecasterFoundation(estimator=model)

# 3. "Fit" only stores the last context_length observations (no training)
forecaster.fit(series=data['target'])

# 4. Point forecast — returns long-format DataFrame: columns ['level', 'pred']
predictions = forecaster.predict(steps=24)

Multi-Series (Global Zero-Shot Model)

Pass a wide DataFrame, a long-format DataFrame (MultiIndex), or a dict[str, pd.Series] to fit.

# series: wide DataFrame — each column is one series
forecaster.fit(series=series)

# Forecast all series
predictions = forecaster.predict(steps=24)

# Forecast a subset
predictions = forecaster.predict(steps=24, levels=['series_1', 'series_2'])

Chronos-2 supports cross_learning=True to share information across series in the batch (ignored in single-series mode):

model = FoundationModel(
    model_id='autogluon/chronos-2-small',
    cross_learning=True,
)

With Exogenous Variables (Chronos-2, TabICL, TabPFN-TS and T0)

Chronos-2, TabICL, TabPFN-TS and T0 (allow_exog=True) accept exogenous variables. TimesFM 2.5 and Moirai-2 ignore them.

# Historical + future exog (must cover the forecast horizon)
forecaster.fit(series=data['target'], exog=exog_train)

predictions = forecaster.predict(steps=24, exog=exog_test)

Prediction Intervals and Quantiles

Foundation models output native quantile forecasts — no bootstrapping or conformal calibration is required.

# Interval (lower/upper bounds from the model's quantiles)
predictions = forecaster.predict_interval(
    steps=24,
    interval=[0.1, 0.9],   # 80% prediction interval (quantiles, 0-1 scale)
)
# Columns: ['level', 'pred', 'lower_bound', 'upper_bound']

# Explicit quantiles
predictions = forecaster.predict_quantiles(
    steps=24,
    quantiles=[0.1, 0.5, 0.9],
)
# Columns: ['level', 'q_0.1', 'q_0.5', 'q_0.9']

For TimesFM 2.5 and Moirai-2, requested quantiles must be a subset of [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9]. Chronos-2, TabICL, TabPFN-TS and TFC-T0 support any quantile in (0, 1).

Choosing a Model

The adapter is resolved automatically from the model_id prefix — no need to import adapter classes directly.

Backtesting

Use the dedicated backtesting_foundation function — it is the only backtester that accepts a ForecasterFoundation. Refit is always disabled internally (the loaded model weights are preserved across folds) and probabilistic output is requested via quantiles, not interval.

from skforecast.model_selection import backtesting_foundation, TimeSeriesFold

cv = TimeSeriesFold(
    steps=24,
    initial_train_size=len(series) - 200,
    refit=False,      # Refit is always disabled for foundation forecasters
)

metric, predictions = backtesting_foundation(
    forecaster=forecaster,
    series=series,
    cv=cv,
    metric='mean_absolute_error',
    quantiles=[0.1, 0.5, 0.9],   # Native model quantiles; no bootstrapping
)

Override the Stored Context

Pass context at predict time to forecast from a different window without refitting — useful for one-off predictions or custom backtesting loops:

predictions = forecaster.predict(
    steps=24,
    context=new_window,        # pandas Series / DataFrame / dict
    context_exog=new_exog,     # Only with exog-aware adapters
    exog=future_exog,
)

If context is longer than the adapter's context_length, it is trimmed automatically to the last context_length observations.

Common Pitfalls

1. Expecting fit() to train the model: it only stores context. The weights come from HuggingFace.
2. Index without frequency: call series.asfreq('h') (or similar) before fit — skforecast requires a frequency.
3. Passing exog to TimesFM 2.5 / Moirai-2: ignored. Only Chronos-2, TabICL, TabPFN-TS and TFC-T0 support exogenous variables.
4. Requesting unsupported quantiles: TimesFM 2.5 and Moirai-2 are restricted to the nine deciles 0.1 … 0.9.
5. Large model downloads: first call can be slow; consider using smaller variants (*-small) for experimentation.
6. Forgetting to install the backend: each foundation model requires its own library (chronos-forecasting, timesfm, uni2ts, tabicl, tabpfn-time-series, tfc-t0). Install only the one(s) you need.