Heimdall Research

All findings · Storm Blackout and Restoration

Which storm had the largest sum of county outage peaks?

Irma has the largest sum of county outage peaks among these 672 storm events: 8.9 million.

Among these 672 storm events, Irma (AL112017) has the largest sum of county peak customers out: 8,867,374 across 329 counties with a numeric peak. Each county contributes its own peak. Those peaks are not one simultaneous count of customers out.

These numbers are Storm Blackout and Restoration version 1.2, the published package (672 storms in version 1.2).

Table

From the table

FigureValue
Sum of county peaks8,867,374
Counties with a peak329
Storm events in the catalog672

Reading

What the data shows

Summing numeric peak_customers_out for event_id AL112017 gives 8,867,374 across 329 counties. That sum is the largest among the 672 storm events. Each county contributes its own peak. Those peaks are not one simultaneous count of customers out. The next sums are Helene 5,911,300, DR-4586 5,214,663, Ian 3,981,026, and Milton 3,736,269.

Context

Why it matters

If you are comparing these storm events, this shows the scale of Irma's county peaks. It is not an outage feed for one day and not a figure for one address.

Method

How it was measured

The sum is numeric peak_customers_out for AL112017. The storm event count is the release storms list. County peaks can overlap, so the sum is not a count of distinct customers. Method on the dataset page.

Limits

What this cannot tell you

Night light is not a utility outage count. County peaks can double-count customers across overlapping service territories when summed. Disclaimer word for word: Not for real-time emergency response or for any decision about one address or property.

Check

Check it yourself

File
storms/utility_by_county.csv
Column
peak_customers_out
Row
event_id AL112017, peak_customers_out nonempty, event listed among 672 storm events
API and assistant
Same key, same data

This API call reads the same cells.

curl "https://api.heimdallresearch.com/v1/storms/AL112017" \
  -H "Authorization: Bearer $HEIMDALL_API_KEY"

This assistant prompt asks for the same cells.

MCP https://api.heimdallresearch.com/mcp question: What is the sum of peak_customers_out for AL112017, and how many counties have a numeric peak?

Citation

Dataset citation

Heimdall Research (2026). Storm Blackout and Restoration (Version 1.2) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.23010005 Concept DOI https://doi.org/10.5281/zenodo.23010004.

Version
1.2
DOI
10.5281/zenodo.23010005

Related

  1. 3,736,269 Finding

    Milton's sum of county outage peaks ranks fifth: 3.7 million.

    Milton (AL142024) sums to 3,736,269 peak customers across 51 counties (5th largest sum). Each county contributes its own peak.

    Read the finding

    Breakdown

    For AL142024, the sum of numeric peak_customers_out is 3,736,269 across 51 counties. That ranks 5th, behind Irma, Helene, DR-4586, and Ian. Each county contributes its own peak. Those peaks are not one simultaneous count of customers out.

  2. 121 days Finding

    After Maria, night-light brightness took 121 days to return to the usual range in the typical county.

    For Maria (AL152017), the median of days_to_normal is 121 days across 46 counties with a value. This column is satellite night-light brightness.

    Read the finding

    Breakdown

    In the county summary table for AL152017, the median of days_to_normal is 121 across 46 counties with a value. days_to_normal counts days of satellite night-light brightness. It is separate from utility hours_to_90pct_restored.

  3. 52.9 hours Finding

    After Irma, the typical county reached 90% of customers restored in 53 hours.

    For Irma, the median county hours to 90 percent restored is 52.9 hours (280 counties with a numeric value).

    Read the finding

    Breakdown

    For AL112017, the median of numeric hours_to_90pct_restored is 52.9 hours across 280 counties. Blank and non-numeric cells are left out. A row with reporting_drop true stays in the median when the hour cell is numeric.

Estimates from public records and satellite night light. Not for real-time emergency response or for any decision about one address or property.

Provided as is, without warranty of any kind.

All findings · Storm Blackout and Restoration