The length of the fire season has not garnered much attention within the broad field of meteorological research on fire regime change. Fire weather research on the Iberian Peninsula is no exception in this case; there is no solid understanding on fire season lengthening in Portugal, although recent decades do suggest ongoing transitions. Based on a complete record of fire occurrence and burned area between 1980 and 2018, we first searched for consistent trends in the monthly distribution of fire activity. To determine day-scale changes, an exceedance date method based on annual cumulative burned area was developed. Results show an early onset of fire activity in a range of 23–50 days and no significant extension into autumn, suggesting that existing projections of the lengthening of the fire season in Portugal over the present century have been already achieved. Fire weather results show a trend in the cumulative Daily Severity Rating (DSR), with the last two decades (2000–2018) displaying an early build-up of meteorological fire danger in late spring and early summer. The detailed spatio-temporal analysis based on the daily Fire Weather Index (FWI) shows that June stands out with the largest increase (year-round) in days per month with an FWI above 38.3, the threshold above which fire conditions make suppression uncertain. This aggravated fire weather is likely sustaining early fire activity, thus contributing to a longer critical fire season.

The study evaluated the ECMWF model ability in forecasting lightning in Portugal during four fire seasons (2019–2022). The evaluation was made based on lightning data from the national lightning detector network, which was aggregated into resolutions of 0.5° and 1° over 3 h periods and analyzed from statistical indices using two contingency tables. The results showed that the model overestimates the lightning occurrence, with a BIAS greater than 1, with a success rate of 57.7% (49%) for a horizontal resolution of 1° (0.5°). The objective analysis was complemented by the spatial lightning distribution analysis, which indicated a time lag between the two data, i.e., the model started predicting lightning before its occurrence and finished the prediction earlier. Furthermore, such analysis revealed the lightning distribution being consistent with some weather patterns. The findings of this study provide insights into the applicability of the ECMWF lightning forecast data in the context of forecasting natural forest fires in Portugal.

This study investigates the Serra da Estrela megafire, located in Portugal, which occurred in August 2022, aiming to explore how changes in weather conditions can modify fire behavior in a fire burning during several days. The study uses a set of fire–atmosphere coupled simulations, referred as EXPn. The MesoNH atmospheric model was coupled to the ForeFire fire propagation model and configured with three nested domains, each comprising a 150 × 150 horizontal grid, with resolutions of 1500 m, 500 m, and 250 m. Regarding the experiments, EXP1 [IGN] corresponds to the ignition phase on 6 August, EXP2 [PYRO] to the development of pyro‐convective clouds on 10 August, whereas EXP3 [REAC] represents the fire reactivation period on 15 August. The first and third periods showed that smoke plumes were transported mainly within the boundary layer, whereas in the second period pyro‐convection reached the middle tropospheric levels, allowing the formation of pyro‐convective clouds. Such clouds were confirmed from radar and satellite observations. Beside the fire‐generated clouds, the study highlighted that propagation of the fire front can suddenly shift due to the interaction between weather, fire and complex terrain. This study confirmed the importance of the use of coupled atmosphere–fire models to represent fire dynamics and their impact on local meteorology. In a global perspective, such an approach provides a framework for assessing wildfire–atmosphere interactions in diverse environments, supporting improved prediction of large wildfires. Overall, it underscores the influence of evolving atmospheric conditions on fire behavior, which is critical for understanding the development of megafires capable of burning over several weeks. This study highlights the crucial need to expand our scientific understanding of fire behavior, enabling its application to other regions worldwide.

Apresentam-se as melhorias levadas a cabo na Região Autónoma da Madeira (RAM), na última década, designadamente no que se refere à ampliação da rede de observação de superfície e à instalação de sistemas de observação remota, tais como o radar meteorológico em Porto Santo, a rede de detetores de trovoadas, constituída por quatro detetores e ainda, outros sistemas que têm permitido dar uma resposta tempestiva ao Serviço Regional de Proteção Civil, à população em geral e aos órgãos de comunicação social.

In the framework of the FireStorm project, four portable weather stations were installed in the Lousã/Estrela mountain range. Given that the Portuguese Institute for Sea and Atmosphere’s sur-face network has two weather stations installed in this region, the new data allows an improved monitoring of the vertical variability of near-surface variables in this mountainous region. As most of the wildfires in mainland Portugal affect areas with complex terrain with elevations below 1200 m and major fires continue to burn overnight, it is also relevant to monitor the vertical changes of meteorological variables in the nighttime period, as these may exhibit large variability. This study provides the first assessment of the available data, with focus on the summer seasons of 2021 and 2022. The results highlight the large variability that was observed in the region and suggest that the risk of extreme fire behaviour in the nighttime period may be underestimated.

Wildfires in mountainous terrain can be extremely challenging to address