Abstract
Alpine rivers are becoming increasingly exposed to atmospheric heatwaves. Because of their strong relationship with air temperature, rivers can experience persistent heat anomalies, known as riverine heatwaves, which can have serious consequences for river ecosystems and the economy. This study aims to improve our understanding of how river water temperature responds to atmospheric heatwaves by focusing on the interplay of various hydro-climatic variables that can strengthen or weaken the thermal sensitivity of rivers to such events. Our results show that the response of water temperature to atmospheric heatwaves can vary substantially, with only 47% of atmospheric heatwaves leading to riverine heatwaves. Riverine heatwave development can be prevented by positive anomalies in discharge and meltwater, while negative anomalies in discharge strengthen the link between atmospheric and river temperatures. Future changes in these hydro-climatic conditions will likely increase the sensitivity of Alpine rivers to atmospheric heatwaves.
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Data availability
The shapefiles of all catchments, including static catchment characteristics, annual regime data and event data are available through HydroShare according to the FAIR data sharing principles: van Hamel, A. (2025)84.
Code availability
A python notebook to generate the figures that are provided in this manuscript and in the Supplementary information is available through HydroShare: van Hamel, A. (2025)84.
References
Perkins, S. E. & Alexander, L. V. On the measurement of heat waves. J. Clim. 26, 4500–4517 (2013).
Caissie, D. The thermal regime of rivers: A review. Freshw. Biol. 51, 1389–1406 (2006).
Leach, J. A., Kelleher, C., Kurylyk, B. L., Moore, R. D. & Neilson, B. T. A primer on stream temperature processes. WIREs Water 10, e1643 (2023).
Sun, J. et al. Impact of extreme atmospheric heat events on river thermal dynamics and heatwaves. J. Hydrol. 659, 133292 (2025).
Johnson, M. F. et al. Rising water temperature in rivers: Ecological impacts and future resilience. WIREs Water 11, e1724 (2024).
Sabater, S. et al. Extreme weather events threaten biodiversity and functions of river ecosystems: evidence from a meta-analysis. Biol. Rev. 98, 450–461 (2023).
Delpla, I., Jung, A. V., Baures, E., Clement, M. & Thomas, O. Impacts of climate change on surface water quality in relation to drinking water production. Environ. Int. 35, 1225–1233 (2009).
van Vliet, M. T. H. et al. Vulnerability of US and European electricity supply to climate change. Nat. Clim. Change 2, 676–681 (2012).
van Vliet, M. T. H., Wiberg, D., Leduc, S. & Riahi, K. Power-generation system vulnerability and adaptation to changes in climate and water resources. Nat. Clim. Change 6, 375–380 (2016).
Barange, M. et al. Impacts of climate change on fisheries and aquaculture: synthesis of current knowledge, adaptation and mitigation options (Food and Agriculture Organization of the United Nations (FAO), Rome, 2018). ISBN: 978-92-5-130607-9.
Tassone, S. J. et al. Increasing heatwave frequency in streams and rivers of the United States. Limnol. Oceanogr. Lett. 8, 295–304 (2022).
Läubli, M. Folgen des Hitzesommers - Flüsse und Bäche bleiben warm, Fischsterben werden sich häufen (2022). Accessed on 1/2/2023 from https://www.tagesanzeiger.ch/fluesse-und-baeche-bleiben-warm-fischsterben-werden-sich-haeufen-297422204406.
Biela, V. R. et al. Premature mortality observations among Alaska’s Pacific salmon during record heat and drought in 2019. Fisheries 47, 157–168 (2022).
Kuroda, M., Kuroki, M., Kurokawa, D., Takeda, K. & Morita, K. A heatwave-related mortality event of endangered Sakhalin taimen Parahucho perryi in northern Hokkaido, Japan. Ichthyol. Res. 73, 170–176 (2026).
Swissinfo. Swiss nuclear power plant shuts down reactor due to the heat (2025). Accessed on 31/7/2025 from https://www.swissinfo.ch/eng/climate-adaptation/beznau-nuclear-power-plant-shuts-down-one-of-its-reactors-due-to-the-heat/89617209.
Sun, J. et al. Long-term daily water temperatures unveil escalating water warming and intensifying heatwaves in the Odra river Basin, Central Europe. Geosci. Front. 15, 101916 (2024).
Zhou, Q. et al. Characteristics of river heatwaves in the Vistula River basin, Europe. Heliyon 10, e35987 (2024).
van Hamel, A. et al. Riverine heatwaves are an emergent climate change risk. Nat. Water 3, 1356–1364 (2025).
van Vliet, M. T. H., Ludwig, F., Zwolsman, J. J. G., Weedon, G. P. & Kabat, P. Global river temperatures and sensitivity to atmospheric warming and changes in river flow. Water Resources Res. 47, W02544 (2011).
Seyedhashemi, H. et al. Regional, multi-decadal analysis on the Loire River basin reveals that stream temperature increases faster than air temperature. Hydrol. Earth Syst. Sci. 26, 2583–2603 (2022).
Michel, A., Brauchli, T., Lehning, M., Schaefli, B. & Huwald, H. Stream temperature and discharge evolution in Switzerland over the last 50 years: annual and seasonal behaviour. Hydrol. Earth Syst. Sci. 24, 115–142 (2020).
Domeisen, D. I. V. et al. Prediction and projection of heatwaves. Nat. Rev. Earth Environ. 4, 36–50 (2023).
Holbrook, N. J. et al. A global assessment of marine heatwaves and their drivers. Nat. Commun. 10, 2624 (2019).
Oliver, E. C. J. et al. Longer and more frequent marine heatwaves over the past century. Nat. Commun. 9, 1324 (2018).
Woolway, R. I., Anderson, E. J. & Albergel, C. Rapidly expanding lake heatwaves under climate change. Environ. Res. Lett. 16, 094013 (2021).
Wang, X., Shi, K., Qin, B., Zhang, Y. & Woolway, R. I. Disproportionate impact of atmospheric heat events on lake surface water temperature increases. Nat. Clim. Change 14, 1172–1177 (2024).
Zhu, S. et al. An optimized NARX-based model for predicting thermal dynamics and heatwaves in rivers. Sci. Total Environ. 926, 171954 (2024).
Sadayappan, K. & Li, L. Riverine heat waves on the rise, outpacing air heat waves. Proc. Natl. Acad. Sci. 122, e2503160122 (2025).
Laizé, C. L. R., Bruna Meredith, C., Dunbar, M. J. & Hannah, D. M. Climate and basin drivers of seasonal river water temperature dynamics. Hydrol. Earth Syst. Sci. 21, 3231–3247 (2017).
Webb, B. W., Hannah, D. M., Moore, R. D., Brown, L. E. & Nobilis, F. Recent advances in stream and river temperature research. Hydrol. Process. 22, 902–918 (2008).
Ouellet, V. et al. River temperature research and practice: Recent challenges and emerging opportunities for managing thermal habitat conditions in stream ecosystems. Sci. Total Environ. 736, 139679 (2020).
van Hamel, A. & Brunner, M. I. Trends and drivers of water temperature extremes in mountain rivers. Water Resour. Res. 60, e2024WR037518 (2024).
Beaufort, A., Diamond, J. S., Sauquet, E. & Moatar, F. Spatial extrapolation of stream thermal peaks using heterogeneous time series at a national scale. Hydrol. Earth Syst. Sci. 26, 3477–3495 (2022).
Fellman, J. B. et al. Stream temperature response to variable glacier coverage in coastal watersheds of Southeast Alaska. Hydrol. Process. 28, 2062–2073 (2014).
Moatar, F. & Gailhard, J. Water temperature behaviour in the River Loire since 1976 and 1881. Comptes Rendus Geosci. 338, 319–328 (2006).
Moore, R. D. et al. Glacier change in western North America: Influences on hydrology, geomorphic hazards and water quality. Hydrol. Process. 23, 42–61 (2009).
Piccolroaz, S., Toffolon, M., Robinson, C. T. & Siviglia, A. Exploring and quantifying river thermal response to heatwaves. Water 10, 1098 (2018).
White, J. C. et al. Drought impacts on river water temperature: A process-based understanding from temperate climates. Hydrol. Process. 37, e14958 (2023).
Anderson, S. & Chartrand, S. A century of variability of heatwave-driven streamflow in melt-driven basins and implications under climate change. Environ. Res. Lett. 19, 114059 (2024).
Zappa, M. & Kan, C. Extreme heat and runoff extremes in the Swiss Alps. Nat. Hazards Earth Syst. Sci. 7, 375–389 (2007).
Feng, M., Zolezzi, G. & Pusch, M. Effects of thermopeaking on the thermal response of alpine river systems to heatwaves. Sci. Total Environ. 612, 1266–1275 (2018).
Sohrabi, M. M., Benjankar, R., Tonina, D., Wenger, S. J. & Isaak, D. J. Estimation of daily stream water temperatures with a Bayesian regression approach. Hydrol. Process. 31, 1719–1733 (2017).
McGregor, G. Synoptic scale atmospheric processes and heatwaves. In McGregor, G. (ed.) Heatwaves: Causes, Consequences and Responses, 207–259 (Springer International Publishing, Cham, 2024).
Fischer, E. M., Seneviratne, S. I., Lüthi, D. & Schär, C. Contribution of land-atmosphere coupling to recent European summer heat waves. Geophys. Res. Lett. 34, L06707 (2007).
Mukherjee, S. & Mishra, A. K. Increase in compound drought and heatwaves in a warming world. Geophys. Res. Lett. 48, e2020GL090617 (2021).
Beniston, M. Warm winter spells in the Swiss Alps: Strong heat waves in a cold season? A study focusing on climate observations at the Saentis high mountain site. Geophys. Res. Lett. 32, L01812 (2005).
Holmberg, E., Messori, G., Caballero, R. & Faranda, D. The link between European warm-temperature extremes and atmospheric persistence. Earth Syst. Dyn. 14, 737–765 (2023).
Tague, C., Farrell, M., Grant, G., Lewis, S. & Rey, S. Hydrogeologic controls on summer stream temperatures in the McKenzie River basin, Oregon. Hydrological Process. 21, 3288–3300 (2007).
Hare, D. K., Helton, A. M., Johnson, Z. C., Lane, J. W. & Briggs, M. A. Continental-scale analysis of shallow and deep groundwater contributions to streams. Nat. Commun. 12, 1450 (2021).
van Vliet, M. T. H. et al. Global river water quality under climate change and hydroclimatic extremes. Nat. Rev. Earth Environ. 4, 687–702 (2023).
Mosley, L. M. Drought impacts on the water quality of freshwater systems; review and integration. Earth-Sci. Rev. 140, 203–214 (2015).
Graham, D. J., Bierkens, M. F. P. & van Vliet, M. T. H. Impacts of droughts and heatwaves on river water quality worldwide. J. Hydrol. 629, 130590 (2024).
Bruno, G. et al. Disentangling the role of subsurface storage in the propagation of drought through the hydrological cycle. Adv. Water Resour. 169, 104305 (2022).
North, R. P. et al. The physical impact of the late 1980s climate regime shift on Swiss rivers and lakes. Inland Waters 3, 341–350 (2013).
van Vliet, M. T. H. et al. Global river discharge and water temperature under climate change. Glob. Environ. Change 23, 450–464 (2013).
Toffolon, M. & Piccolroaz, S. A hybrid model for river water temperature as a function of air temperature and discharge. Environ. Res. Lett. 10, 114011 (2015).
Michel, A. et al. Future water temperature of rivers in Switzerland under climate change investigated with physics-based models. Hydrol. Earth Syst. Sci. 26, 1063–1087 (2022).
Zhu, S. & Piotrowski, A. P. River/stream water temperature forecasting using artificial intelligence models: a systematic review. Acta Geophys. 68, 1433–1442 (2020).
Acuña Espinoza, E. et al. Analyzing the generalization capabilities of a hybrid hydrological model for extrapolation to extreme events. Hydrol. Earth Syst. Sci. 29, 1277–1294 (2025).
Brunner, M. I., Götte, J., Schlemper, C. & Van Loon, A. F. Hydrological drought generation processes and severity are changing in the Alps. Geophys. Res. Lett. 50, e2022GL101776 (2023).
Forzieri, G. et al. Ensemble projections of future streamflow droughts in Europe. Hydrol. Earth Syst. Sci. 18, 85–108 (2014).
Brunner, M., Farinotti, D., Zekollari, H., Huss, M. & Zappa, M. Future shifts in extreme flow regimes in Alpine regions. Hydrol. Earth Syst. Sci. 23, 4471–4489 (2019).
Beniston, M. & Goyette, S. Changes in variability and persistence of climate in Switzerland: Exploring 20th century observations and 21st century simulations. Glob. Planet. Change 57, 1–15 (2007).
Hoffmann, P., Lehmann, J., Fallah, B. & Hattermann, F. F. Atmosphere similarity patterns in boreal summer show an increase of persistent weather conditions connected to hydro-climatic risks. Sci. Rep. 11, 22893 (2021).
Russo, S., Sillmann, J. & Fischer, E. M. Top ten European heatwaves since 1950 and their occurrence in the coming decades. Environ. Res. Lett. 10, 124003 (2015).
Russo, S. et al. Magnitude of extreme heat waves in present climate and their projection in a warming world. J. Geophys. Res.: Atmos. 119, 12,500–12,512 (2014).
Lhotka, O., Kyselý, J. & Farda, A. Climate change scenarios of heat waves in Central Europe and their uncertainties. Theor. Appl. Climatol. 131, 1043–1054 (2018).
Manning, C. et al. Increased probability of compound long-duration dry and hot events in Europe during summer (1950-2013). Environ. Res. Lett. 14, 094006 (2019).
Geirinhas, J. L. et al. Recent increasing frequency of compound summer drought and heatwaves in Southeast Brazil. Environ. Res. Lett. 16, 034036 (2021).
Ráman Vinná, L., Bigler, V., Schilling, O. S. & Epting, J. Multi-fidelity model assessment of climate change impacts on river water temperatures and thermal extremes and potential effects on cold-water fish in Switzerland. Hydrol. Earth Syst. Sci. 29, 5931–5953 (2025).
Klingler, C., Schulz, K. & Herrnegger, M. LamaH-CE: LArge-SaMple DAta for hydrology and environmental sciences for Central Europe. Earth Syst. Sci. Data 13, 4529–4565 (2021).
Höge, M. et al. CAMELS-CH: hydro-meteorological time series and landscape attributes for 331 catchments in hydrologic Switzerland. Earth Syst. Sci. Data 15, 5755–5784 (2023).
Schimanke, S. et al. CERRA sub-daily regional reanalysis data for Europe on single levels from 1984 to present. In Copernicus Climate Change Service (C3S) Climate Data Store (CDS). https://doi.org/10.24381/cds.622a565a (2021).
Wood, R. R. et al. Comparison of high-resolution climate reanalysis datasets for hydro-climatic impact studies. Hydrol. Earth Syst. Sci. 29, 4153–4178 (2025).
Sutanudjaja, E. H. et al. PCR-GLOBWB 2: a 5-arcmin global hydrological and water resources model. Geosci. Model Dev. 11, 2429–2453 (2018).
Hoch, J. M., Sutanudjaja, E. H., Wanders, N., van Beek, R. L. P. H. & Bierkens, M. F. P. Hyper-resolution PCR-GLOBWB: opportunities and challenges from refining model spatial resolution to 1km over the European continent. Hydrol. Earth Syst. Sci. 27, 1383–1401 (2023).
Janzing, J. et al. Hyper-resolution large-scale hydrological modelling benefits from improved process representation in mountain regions 29, 7041–7071 (2025).
van Jaarsveld, B. et al. A first attempt to model global hydrology at hyper-resolution. Earth Syst. Dyn. 16, 29–54 (2025).
Karger, D. N. et al. Climatologies at high resolution for the earth’s land surface areas. Sci. Data 4, 170122 (2017).
Karger, D. N. et al. Climatologies at high resolution for the earth’s land surface areas. EnviDat. https://doi.org/10.16904/envidat.228 (2021).
Tassone, S. J., Besterman, A. F., Buelo, C. D., Walter, J. A. & Pace, M. L. Co-occurrence of aquatic heatwaves with atmospheric heatwaves, low dissolved oxygen, and low pH events in estuarine ecosystems. Estuaries Coasts 45, 707–720 (2022).
Jensen, L. F. et al. Local adaptation in brown trout early life-history traits: implications for climate change adaptability. Proc. R. Soc. B: Biol. Sci. 275, 2859–2868 (2008).
Butzge, A. J. et al. Early warming stress on rainbow trout juveniles impairs male reproduction but contrastingly elicits intergenerational thermotolerance. Sci. Rep. 11, 17053 (2021).
van Hamel, A. River temperature response to atmospheric heatwaves in the European Alps, HydroShare, https://doi.org/10.4211/hs.2d0006fde39d411eb80093991eab85ba (2026).
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The authors thank the Swiss Federal Office for the Environment and the Austrian Hydrographic Service for data provision.
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A.v.H.: conceptualization, formal analyses, writing first draft of manuscript. J.J.: data generation and curation, revision and editing of manuscript. M.B.: conceptualization, revision and editing of manuscript, supervision.
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van Hamel, A., Janzing, J. & Brunner, M.I. River temperature response to atmospheric heatwaves is modulated by discharge and meltwater. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03269-6
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DOI: https://doi.org/10.1038/s43247-026-03269-6


