What is a heating degree day (HDD)?

A Heating Degree Day (HDD) measures how much the daily average temperature falls below a baseline (typically 65 degrees Fahrenheit in the U.S.). It is the standard metric energy markets use to estimate heating demand for natural gas and electricity. Power and gas traders on PJM, ISO-NE, NYISO, MISO, and Henry Hub use HDD forecasts to anticipate winter demand and size term positions before the curve reprices.

What is a cooling degree day (CDD)?

A Cooling Degree Day (CDD) measures how much the daily average temperature exceeds a baseline (typically 65 degrees Fahrenheit). It is the standard metric for cooling demand and summer power load. Energy traders on ERCOT, CAISO, MISO, PJM, and SPP use CDD forecasts to anticipate summer peak load, gas burn for power generation, and price spikes during heat domes and extended hot stretches across the U.S.

How do power and gas traders use degree-day forecasts?

Power and gas traders use degree-day forecasts to anticipate demand shifts and price moves across U.S. ISOs and gas regions. Day-ahead traders feed hourly HDD and CDD into load models for PJM, ERCOT, and MISO. Term traders size winter and summer positions on subseasonal and seasonal HDD and CDD outlooks. Gas traders track GWDD across EIA regions to forecast storage withdrawals before the Thursday EIA report.

What U.S. trading markets does World Climate Service cover?

World Climate Service U.S. Trading Markets covers every U.S. power ISO (PJM, MISO, NYISO, CAISO, ERCOT, ISO-NE, SPP), every EIA natural gas region, every ERCOT load zone, and all 48 contiguous states. Forecasts span Heating Degree Days, Cooling Degree Days, Gas-Weighted Degree Days, and Population-Weighted Degree Days across 90+ U.S. regions, delivered through a browser interface and a direct API for systematic trading workflows.

What is the difference between gas-weighted (GWDD) and population-weighted (PWDD) degree days?

Population-Weighted Degree Days (PWDD) weight regional temperatures by population to estimate residential and commercial heating and cooling demand, the standard input for power load forecasting in PJM, ERCOT, NYISO, and other U.S. ISOs. Gas-Weighted Degree Days (GWDD) weight regional temperatures by historical natural gas consumption to estimate gas demand at Henry Hub and across EIA regions. Power traders rely on PWDD; gas traders rely on GWDD.

U.S. HDD & CDD Forecasts for Natural Gas and Power Trading Desks

Win more weather-based trades with medium-range, weekly, and monthly HDD/CDD forecasts for U.S. power and natural gas markets.

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Track HDD/CDD Risk

Anticipate degree-day changes using our forecast analyses.

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Power ISOs, EIA gas regions, ERCOT zones, 48 states.

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U.S. Trading Markets Tools for Energy Trading Desks

U.S. Trading Markets Interface

Anticipate changes in U.S. HDD/CDD forecast risk across power ISOs, EIA gas regions, ERCOT zones, and 48 states.

U.S. Trading Markets API

Integrate bias-corrected U.S. HDD/CDD forecasts into trading systems and quant models to automate weather-driven signal generation.

From Degree-Day Signal to Trading Decision

Manage Risk and Opportunity

Manage HDD and CDD risk and opportunity across U.S. power and gas markets.

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Daily, weekly, and monthly HDD/CDD forecast time horizons available as a web-based interface or API.

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Develop U.S. HDD/CDD trading strategies based on bias-corrected forecast skill.

Inside Each U.S. Trading Markets Tool

U.S. Trading Markets Interface

Browser-based bias-corrected U.S. degree-day forecasts for energy meteorologists.

4Forecast Models

4Degree-Day Variables

90+U.S. Regions

2Climatology Modes

Analyze HDD/CDD forecast risk across U.S. ISOs, EIA gas regions, ERCOT zones, and states.
Digest bias-corrected GWDD, PWDD, HDD, and CDD guidance so the desk acts on what the models tend to get right.
Compare AIFS, ECMWF, GEFS, CFSv2, and Multi-Model output to gauge confidence in pattern transitions.
Toggle Anomaly, Change, and Progression views to see how the HDD/CDD forecast signal evolves.

U.S. Trading Markets API

API access to bias-corrected U.S. degree-day forecasts for trading systems and quants.

5Forecast Models

4Degree-Day Variables

90+U.S. Regions

DirectSystem Integration

Stream bias-corrected HDD/CDD forecasts directly into your trading systems and quant models.
Find systematic signals from population-weighted and gas-weighted U.S. HDD/CDD forecast data.
Automate HDD/CDD forecast change alerts across U.S. ISOs, EIA regions, ERCOT zones, and states.

Built for Power and Natural Gas Desks

Refined Since 2009

Continuously refined since 2009 through direct engagement with power and gas trading desks.

Bias-Corrected Forecasts

Objective, consistently structured, and historically deep GWDD, PWDD, HDD, and CDD guidance.

Built for Both Workflows

The Interface gives energy meteorologists the views they need to translate forecast risk to the trader. The API gives quantitative analysts the data feeds they need to build systematic degree-day signals.

Energy Trading Focus

Every U.S. degree-day tool is built around the workflow of energy meteorologists and quants on power and gas trading desks.

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Translate U.S. degree-day signals into clearer trading desk briefings.

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