Twenty-five years of continuous temperature and salinity observations on the Uruguayan Atlantic coast.

Long-term time-series are crucial for studying climate variability, climate change, and ecological processes.This study presents the first 25-year continuous record of temperature and salinity observations on the Uruguayan Atlantic coast (34.6S, 54.1W), covering the period from March 1, 1996, to February 28, 2021 (ongoing measurements).The mean annual temperature was 17.5 C, with a seasonal amplitude of 10.2 C, ranging from a monthly mean minimum of 12.4 C in August to a monthly mean maximum of 22.6 C in February.Mean annual salinity was 26.2 psu, also exhibiting seasonality, with an amplitude of 6.4 psu, a monthly minimum of 22.6 psu in June, and a monthly maximum of 29.0 psu in January.Temperature shows a significant positive trend of approximately 1C over 25 years, consistent with satellite data.Additionally, a daily cycle with similar amplitude underscores the importance of comparing measurements taken at the same hour of the day to analyze daily coastal temperature variability.No significant trend was detected in salinity.Finally, we show a significant negative correlation of salinity in La Paloma with Ro de la Plata runoff and alongshore winds.In particular, extremely low salinity events in La Paloma are associated with extremely high Ro de la Plata runoff and predominance of southwesterly winds, often after an El Nio event.Climatologically, these conditions are optimal during May.