Throughout 2024, Spain reached its warmest average temperature in the month of August, at 25 degrees Celsius. Meanwhile, December was the coldest month that year, with a recorded mean temperature of 7.4 degrees Celsius.

Spain's average temperature usually peaks in the summer months of July and August, and reaches its lowest values in December of each year. In January 2024, the mean temperature in Spain stood at 8.4 degrees Celsius, up from 2.5 degrees Celsius in the same month of the previous year. During the period in consideration, the Mediterranean country registered its warmest average temperature in July 2020, at 26 degrees Celsius. Meanwhile, mean temperatures reached a record low in January 2021, at just over five degrees Celsius.

The average temperature in Spain stood at 15 degrees Celsius in 2024. This represented a slight decrease from the previous year, but an anomaly of 1.1 degrees Celsius above the annual mean from 1991 to 2020. During the period in consideration, average temperatures in the Mediterranean country reached a record high in 2017, at some 16.2 degrees Celsius.

Regardless of whether the rain in Spain stays mainly in the plain, the truth is annual precipitations in the Mediterranean country experienced a downward trend in recent years, with around 536 millimeters of rainfall recorded in 2023. Nevertheless, this figure increased in 2024. For instance, March – one of Spain's wettest months – registered just over 148 millimeters of rain in 2024, up 24 percent from the same month the previous year. However, the record high of 163 millimeters was recorded in March 2018. Spain: Europe’s suntrapMany picture Spain as a dream summer holiday destination – Mediterranean cuisine in the form of tapas, great beaches, and what many visit the country for – its warm climate and sweet sunshine. This enthusiasm for the European country is then not too surprising, since most of its sunniest areas exceeded 3,000 hours of sunshine according to data provided by the Spanish Statistics Institute. Tourism constitutes an essential industry for the Spanish economic systemTravel and tourism have become one of the leading engines of growth for the Spanish economy, featuring an ongoing increase in the GDP contribution over the last years – despite a drop due to the COVID-19 pandemic – and is projected to reach nearly 225 billion euros in 2025.

Early instrumental observations are an important tool to understand multidecadal climate variability or put in context specific extreme phenomena. This paper provides early instrumental data recovered in Latin-America and the Caribbean. Data have been retrieved from 20 countries (Argentina, Bahamas, Belize, Brazil, British Guiana, Chile, Colombia, Costa Rica, Cuba, Ecuador, France (Martinique and Guadalupe), Guatemala, Jamaica, Mexico, Nicaragua, Panama, Peru, Puerto Rico, El Salvador and Suriname) and they cover the 18th and 19th centuries. The main meteorological variables retrieved are air temperature, atmospheric pressure and precipitation but other variables, such as humidity, wind direction, or state of the sky have been retrieved when possible. In total, more than 300 000 early instrumental observations have been rescued (96% with daily resolution). Special effort has been done to document all the available metadata (instruments, observers, methodology of observation...) in order to allow further post processing. The compilation is far from being exhaustive but the data set will contribute to a better understanding of the climate variability in the region and to enlarge the overlapping period between instrumental data and natural and documentary proxies.

Table A1 shows the geographical and topographical data, as well as the Köppen-Geiger climate classification of the 414 radiometric Spanish stations used for training or validation purposes. Table A2 shows experimental values of monthly averages of maximum and minimum daily temperatures, and daily global solar irradiation on horizontal surface, as well as calculated values of monthly averages of daily extraterrestrial irradiation, for Spanish stations listed in Table A1. Table A3 shows the geographical and topographical data, as well as the Köppen-Geiger climate classification of the 16 non-Spanish stations used for validation purposes. Table A4 shows experimental values of monthly averages of maximum and minimum daily temperatures, and daily global solar irradiation on horizontal surface, as well as calculated values of monthly averages of daily extraterrestrial irradiation, for non-Spanish stations listed in Table A3.

Co-trending analysis (Spain monthly data across stations, AEMET, 1970–2019).

Climate model simulations of the PETM (Paleocene-Eocene Thermal Maximum) warming have mainly focused on replicating the global thermal response through greenhouse forcing, i.e. CO2, at levels compatible with observations. Comparatively less effort has gone into assessing the skill of models to replicate the response of the hydrologic cycle to the warming, particularly on regional scales. Here we have assembled proxy records of regional precipitation, focusing on the Mid-Atlantic Coasts of North America (New Jersey) and Europe (Spain) to test the response of the hydrologic system to greenhouse gas forcing of the magnitude estimated for the PETM (i.e., 2x). Given evidence that the PETM initiated during a maximum in eccentricity, this includes the response under neutral and extreme orbital configurations. Modeled results show excellent agreement with observations in Northern Spain, with a significant increase in both mean annual and extreme precipitation resulting from increased CO2 levels under a neutral orbit. The Mid Atlantic Coast simulations agree with observations showing increases in both overall and extreme precipitation as a result of CO2 increases. In particular, the development of sustained atmospheric rivers might be significantly contributing to the extremes of the eastern Atlantic, whereas extratropical cyclones are likely contributing to the extremes in the western Atlantic. With an eccentric orbit that maximizes insolation during boreal summer, there is a suppression of precipitation in the eastern Atlantic and an amplification in the western Atlantic which may account for observations in the relative timing of the sedimentary response to the carbon isotope excursion associated with the PETM.

Methods A series of experiments simulating the PETM warming have been conducted (Kiehl et al., in prep; Shields et al., in prep) utilizing the high resolution (0.25°) CAM5, Version 5.3, with fixed sea surface temperatures and finite volume dynamical (FV) core, with 30 levels in the vertical for the atmosphere component (Neale et al., 2010; Park et al., 2014). The land component is the Community Land Model, Version 4 (CLM4) (Lawrence et al., 2011), also at 0.25° resolution, with the river transport model (RTM) at 1° resolution. Organic aerosol emissions were produced by running MEGAN (Model of Emissions of Gases and Aerosols) approximated from PETM biomes using DeepMIP protocols (Guenther et al., 2012; Lunt et al., 2017). The boundary conditions and sea surface temperatures from this model were obtained from a fully coupled LP and PETM FV 2° CESM1.2.2 (Community Earth System Model, Version 1.2) with output taken at a monthly temporal resolution over 1800 years.

Output was obtained from CAM5 at 6 hourly, daily, and monthly temporal resolution for over 20 years. The model was run with late Paleocene CO2 values of 680 ppmv (hereafter referred to as LP) and PETM CO2 values of 1590 ppmv (hereafter referred to as PETM). Methane was held at 16 ppmv in all runs. Additionally, in order to test the impact of orbital forcing, the model was run with both a neutral orbit and a configuration that maximized solar insolation over the northern hemisphere (i.e. High eccentricity, perihelion NH summers), hereafter referred to as OrbMax. Solar forcing was calculated based on a solar constant of 1355 Wm-2 consistent with Kiehl et al. (2018). The four runs are therefore referred to as LP, PETM, LP OrbMax, PETM OrbMax. Paleocoordinates for each location were set over a 2° by 2° area and were taken from the DeepMIP protocols (Lunt et al., 2017). EMA was set to 34.5°-36.5°N, 0°-2°E. WMA was set to 41°-43°N, 49°-51°W. In order to account for the time required for the model to reach equilibration, data was trimmed to the final 15 years of the 20-year model run.

The parameters of interest include median and 1st and 3rd quartile monthly precipitation and runoff to track both annual and seasonal variation, and exceedance frequency to track storm intensity and to track changes in frequency of storm events. Exceedance frequency is calculated as P=m÷(n+1), wherein P is the exceedance frequency, m is the rank of a given event, and n is the total number of events.

Spain is a major European holiday destination. Besides its cultural and architectural appeal, the Mediterranean country draws in millions of tourists in search of the warm Spanish sun. This sunshine stays mainly in southern, coastal and insular areas of Spain, with Huelva topping the list of sunniest Spanish cities at over 3.2 thousand sunshine hours in 2018. Major coastal holiday destinations, such as Malaga, Almeria or Alicante also made the list, all of them with over three thousand hours of sunshine in 2018. In contrast, Bilbao ranked as the Spanish area with the lowest number of sunshine hours in 2017.

August: the driest and hottest month in Spain Most of that sunshine is concentrated in August, which also ranked as the hottest month in Spain in 2018. The Spanish mean temperature for the said month averaged out at 25.6 degrees, while the coldest month that year was February, with an average of 6.9 degrees Celsius. In 2017, the rainiest month was November, when over 111 millimeters of precipitation were registered on average in Spain. The driest month was again August, which recorded only an average of 18.2 millimeters of precipitation that year.

Tourism constitutes an essential industry for the Spanish economic system Travel and tourism have become one of the leading engines of growth for the Spanish economy, featuring an ongoing increase in the GDP contribution over the last years and projected to reach approximately 178 billion euros in 2018. Spain ranked second on the World Tourism Organization’s list of most visited countries in the world, with its number of international visitors amounting to nearly 82 million in 2017. The Mediterranean country is also one of Europe’s favorite holiday destinations in 2018 – the United Kingdom, Germany and France appeared in the leading positions of the largest number of international visitors to Spain by country of residence, as confirms the latest studies.