What is already known:
What this study adds:
In the past 5 years, California has experienced an increase in wildfires during the fire season, resulting from long and dry summers, and in 2020 experienced the most extreme and dangerous wildfires in its history. These 9,917 fires recorded burned over 4 million acres, damaged over 10,000 structures, and caused 33 fatalities. This unprecedented fire event has led to increased interest in fire weather and research on the weather conditions that led to it. Fire weather is described as the meteorological conditions favorable for fire ignition and spread. Additionally, weather conditions have an impact on vegetation fuels and so on fire combustion. The purpose of this study is to focus on 10 years of climatology over northern and southern California characterized by different vegetations to find any trends and anomalies that can explain the extremity of this 2020 event. By using in situ data of temperature and precipitation, we found that 2020 was particularly characterized by an intense drought over the year which could result from a La Niña event. Drought conditions in winter and summer (with positive anomalies of temperature and negative anomalies of precipitation) seem to explain the intense temperate forest fires of the northern region. However, the same conditions in the grassland southern region suggest that other factors might have a role such as the Santa Ana wind. Future studies should hence look at wind and topography information for the grassland southern region.