Record-warm July boosts solar in North, dampens South and East

In a new weekly update for pv magazine, Solcast, a DNV company, reports that persistent high‑pressure over Scandinavia delivered significantly elevated irradiance up to 30 % above normalin July, while central and eastern Europe faced reduced solar generation under increased cloud cover and rainfall.

In July, persistent high‑pressure over Scandinavia delivered significantly elevated irradiance up to 30 % above normal, while central and eastern Europe faced reduced solar generation under increased cloud cover and rainfall. Meanwhile, elevated wildfire smoke from the eastern Mediterranean and the Iberian Peninsula, combined with transcontinental aerosols, suppressed clear sky irradiance by around 5 % across northern Europe, according to analysis using the Solcast API.

Across Scandinavia, persistent high‑pressure delivered warm and sunny skies, improving solar generation. July irradiance exceeded average values by 10% to 30%, with heat records shattered, including a remarkable 30 C reading within the Arctic Circle in Norway, and an unprecedented 13‑day streak of 30 °C temperatures in Finland. These extremes marked the longest warm‑spell on record for that latitude.

Simultaneously, Turkey registered its highest recorded temperature at 50.5 °C at the end of the month. July 2025 overall ranked as the third‑warmest July globally, with the global average surface temperatures running approximately 1.25 C above pre‑industrial baselines. Europe’s average surface temperature was significantly higher than that global average increase, contributing significantly to the record-breaking warmth observed in July.

In contrast, regions through central and eastern Europe, including Germany, Austria, Poland, Hungary, the Baltic states, and northern Italy, remained outside the high‑pressure envelope and grew increasingly cloudy toward the month’s end. These areas recorded irradiance deficits of 10 % to 30 % below July norms.

A mid‑July cold trough drastically shifted dynamics for regions that had been under intense heat early in the month suddenly faced increased rainfall and localized flooding that compounded solar underperformance. For Germany, this resulted in the worst July on
record for solar potential. Whilst this drop in solar potential was bad news for solar asset owners and operators looking to optimize performance, at a grid scale the ongoing pace of increasing solar capacity means that amongst a “bad year” for July solar weather, solar
power still delivered more than 76.66 GWh to the German grid.

Meanwhile, wildfire smoke from Southern Europe also impacted solar generation. Clear sky irradiance across most northern European countries ran about 5 % below normal levels, even before cloud effects.

This was driven by active fire seasons in Southern Europe, particularly in eastern Mediterranean regions and on the Iberian Peninsula, which burned roughly twice as many hectares as in July 2024. Smoke plumes from these fires and aerosols from burning Canadian forests traversed across continents, creating an aerosol‑laden atmosphere that suppressed solar input across northern Europe.

Solcast produces these figures by tracking clouds and aerosols at 1-2 km resolution globally, using satellite data and proprietary AI/ML algorithms. This data is used to drive irradiance models, enabling Solcast to calculate irradiance at high resolution, with typical bias of less than 2%, and also cloud-tracking forecasts. This data is used by more than 300 companies managing over 150GW of solar assets globally.