Extreme Weather Events in July Drive Divergent Solar Production Trends Across North America
Key Insights
North America experienced varied solar production in July, with the Southwest U.S. seeing significant gains while Canada and parts of the East faced declines due to extreme weather.
High-pressure systems boosted irradiance in Nevada, Arizona, and New Mexico, leading to nearly 20% above-average solar output in those regions.
Conversely, widespread cloud cover, tropical storms, and flash flooding in Texas and the Carolinas severely impacted solar generation in eastern and central states.
A late-July heat dome, while reducing cloud cover, posed efficiency challenges for solar panels and operational difficulties across much of the continent.
July's extreme weather, driven by warmer ocean temperatures and a weaker-than-usual jet stream, significantly altered solar energy production across North America, creating a stark east-west divide in irradiance levels. This variability underscores the critical role of climate patterns in renewable energy asset performance and operational planning.
Analysis using the Solcast API revealed that the southwestern United States experienced the strongest solar conditions. High-pressure systems delivered near cloudless skies, boosting irradiance by almost 20% above average in solar-rich Nevada, Arizona, and New Mexico. East of Texas, states from Arkansas to the Carolinas also outperformed seasonal expectations, seeing irradiance levels 5% to 10% above normal despite above-average rainfall. In contrast, most of Canada endured widespread cloud cover due to a strong low-pressure system, leading to below-average solar exposure. This east-west divergence was particularly evident on July 4th, when Independence Day celebrations in the eastern and central states were affected by widespread storms and rainfall, reducing solar output, while the western half of the country remained clear.
Texas bore the brunt of the most severe weather impacts, with flash flooding during the Independence Day weekend claiming at least 135 lives. This flooding was exacerbated by moisture drawn from the Gulf of Mexico, including remnants of Tropical Storm Barry, which stalled over the state and triggered prolonged thunderstorms. Elevated sea surface temperatures contributed to increased atmospheric moisture across the continent, sustaining flood risks throughout the month, with Tropical Storm Chantal bringing similar conditions to the Carolinas, and localized events impacting New Mexico, Kansas City, and parts of New York.
In the final weeks of July, a widespread heat dome settled over much of North America, bringing extreme temperatures from coast to coast. While these high-pressure systems typically suppress cloud cover, thereby aiding irradiance, the intense heat can significantly reduce the efficiency of photovoltaic panels and complicate field operations. During this period, over half of the U.S. population was under heat alerts, with cities like Tampa breaking long-standing records, surpassing 100°F for the first time in 135 years of data.
Solcast generates these figures by tracking clouds and aerosols at 1-2km resolution globally, leveraging satellite data and proprietary AI/ML algorithms. This high-resolution data drives irradiance models, enabling Solcast to calculate solar exposure with a typical bias of less than 2%, alongside providing cloud-tracking forecasts. This critical data is utilized by over 350 companies managing more than 300 GW of solar assets worldwide, highlighting the industry's reliance on precise meteorological insights for operational optimization and risk management.