Weather volatility is playing an increasing role in power and gas markets as renewables capacity expands and supply-demand balances tighten. Traditional price hedges capture part of this uncertainty, but often leave weather-driven volume and shape risks unaddressed, pushing market participants to explore weather derivatives as a complement to standard hedging strategies. Argus spoke to Theresa Kammel and Pierre Buisson from German reinsurance firm Munich Re about where the exposures lie and how firms are using the expanding toolkit of weather derivatives. Edited highlights follow:
In power and gas, what do weather derivatives solve that standard price hedges do not?
Weather derivatives provide a direct and efficient hedge for weather-driven volume risk.
With a weather derivative, an energy retailer can directly hedge the impact of a cold spell on gas consumption, or a wind farm owner can hedge how many megawatt hours a wind fleet actually generates. For these exposures, they offer a more direct form of risk transfer than standard price hedges.
They are also increasingly leveraged by utilities and commodity traders as hedges against the impact of weather conditions on prices. Weather derivatives allow market participants to isolate the weather component in price formation and trade the underlying fundamentals of power or gas without having to worry about weather outcomes in delivery. As weather increasingly drives physical flows and intraday price dynamics, weather risk has become a first-order earnings variable rather than a secondary uncertainty.
For someone used to futures and options, what is the right way to think about a weather derivative?
Weather derivatives are standard financial derivatives. Instead of a commodity price, the underlying factor is an objective weather index — temperature, wind, solar irradiation, precipitation or a generation proxy index. Settlement is always in cash. There is no physical delivery.
They can be thought of as a Lego box. The peril, location — or basket — risk period, strike and payout structure (swap, option, collar, exotic) are combined in multiple ways to closely match the underlying exposure.
For example, a gas retailer concerned about a milder-than-expected winter could buy a heating degree day option linked to cumulative temperatures over January. If the index settles below a predefined strike, the contract pays out automatically in cash based on the shortfall. Settlement is objective and does not require proof of physical loss.
How do you break down "weather risk" in energy markets?
The answer is threefold — volume risk, average price risk and shape risk.
First, volume risk — how much energy is produced or consumed relative to expectations. Historically, weather primarily affected demand through temperatures but today, risk is shifting to the supply side as renewables capacity increases.
Second, average market price risk — adverse weather conditions impact energy prices. Cold winter temperatures lift gas prices, dry and low wind conditions push power prices higher, while sunny summers increasingly weigh on power prices.
Finally, shape risk — on an hourly level, weather conditions are now putting significant pressure on our power systems and asset economics. High wind and solar output can trigger negative prices, while day-ahead, top-bottom spreads are directly linked to weather volatility, etc. Weather derivatives are now commonly customised to hedge these effects directly.
Which parts of a power portfolio are most exposed to weather in ways traditional hedges cannot capture?
Any cash flow that depends on realised weather, not just energy prices.
Renewables generation is the clearest example, but the exposure is much broader. Temperature drives heating and cooling demand — particularly important nowadays with the development of heat pumps — and therefore retail margins. Hydro output depends on rainfall and snowmelt timing, and many trading books carry implicit exposure to wind and solar conditions.
Consider a portfolio long on power. A trader may be confident that prices will be higher by spot delivery based on fundamentals, but the position remains exposed to wind and solar conditions at delivery. Strong renewables output could force power to be sold at significantly lower-than-expected prices. Such losses are difficult to hedge with price instruments alone but can be directly mitigated using weather derivatives linked to renewable output or temperature.
Are you seeing more interest in wind and solar products specifically?
Yes. With tighter capacity margins, even a few weeks of adverse weather can now materially impact earnings by tens of millions of euros.
Wind and solar variability has become a system-wide P&L [profit and loss] driver. When output underperforms, conventional generation is called upon to fill the gap and prices jump. As a result, demand is rising not only for wind and solar generation indices, but also for residual load proxies and critical-period structures that respond to system stress events, typically associated with dunkelflaute conditions.
What seasonal patterns do you observe in weather hedging activity?
In Europe, activity clusters around key risk windows. Winter temperature risk, peak wind seasons, sunny spring and summer months and hydro refill and snowmelt periods.
A notable trend is growing demand for flexible structures that allow notionals to be adjusted as the season unfolds, rather than fixed far in advance, reflecting the dynamic nature of modern energy portfolios and the tremendous uncertainty in energy supply.
Which products are most liquid today, and how should liquidity be understood in this market?
The market remains predominantly OTC [over the counter], traded under ISDA, alongside some standardised exchange contracts.
Liquidity is defined pragmatically as the ability to obtain competitive quotes for key perils, regions and tenors, and to resize or unwind positions as exposures evolve. For dynamic energy portfolios and trading books, this practical liquidity matters more than continuous screen trading.
How do you see exchange and OTC trading coexisting going forward?
A hybrid model is likely to emerge.
Exchanges will serve the most standardised exposures, offering transparency and clearing, while OTC markets will remain essential for bespoke needs such as specific locations, hybrid pay-offs or multi-peril structures. Standardisation is likely to expand where it adds value, while customisation will remain central to the OTC weather derivatives market, where bespoke risk transfer solutions are traded.
What is the biggest misconception about weather hedging — and the key takeaway?
Rather than a single misconception, what stands out is the uneven maturity of the weather derivatives market.
Numerous large companies are extremely active with dedicated weather trading desks, while some well-known firms remain largely absent. Active participants tend to take a more advanced approach to risk management, but this is very much an open market for all. As awareness grows, participation is likely to broaden.
As for a key takeaway, weather derivatives allow energy companies to hedge a clearly identifiable, objectively measurable risk driver — the weather itself — in a transparent, cash-settled way. When layered on top of price hedges, they complete the hedge stack and turn earnings volatility into a manageable financial variable.
