## 3 Results and Discussion
### Teleconnection Patterns
During the months of June and August, this pattern has shown a negative correlation throughout the territory studied (30.2% and 28.5% respectively of meteorological stations), mainly in southern areas of the State. It is remarkable that at the end of autumn and the whole winter, a positive correlation is found mainly in North California's meteorological stations. This is consistent with other research carried out in the United States, where the authors showed that there is a high correlation in the increase of temperature in winter due to this pattern [27; 41]. Positive phases of Pacific-North America (PNA) are associated with above-average temperatures in the western and below-average temperatures in south-eastern U.S. The PNA pattern has its largest variability during winter [89]. Amongst the teleconnection indices studied, the Western Pacific Oscillation (WPO) has the highest percentage of statistically significant negative correlations with temperature (Figure 7). From December to April, high correlation values between WPO and temperatures were observed throughout the territory with 42.4% (January) to 95.9% (March) of the stations having significant negative correlations. However, no precise spatial area of influence can be identified for this pattern. We have to take into account that WPO is a temporary pattern and this could explain why it mainly affects the temperatures of winter [30] and spring months in the State of California (Figures 4 and 7). Furthermore, PDO and PNA are the two teleconnection patterns that display a high percentage of stations with significant positive correlation while WPO has shown the highest percentages of negative correlation. These results bear striking similarities with previous investigations undertaken in California with different surveillance periods [19; 22; 90]. If we consider the results regarding the Eastern-Pacific Oscillation (EPO) (Figure 8), we can state that 57.0% of stations have shown a significant positive correlation in November along with PNA and, to a lesser extent, PDO. Positive phases of EPO happen when pressure values are maintained in Alaska and high pressure is found in the northeast of Hawaii. This affects east California, making winters warmer than normal. In December, the EPO pattern had no data because there were no values available for the period studied on the datasheet of the Climate Prediction Centre (CPC, NOAA). Searching for alternative values for this pattern in December was not considered in order not to mix diverse information  
Figure 6: Percentage of meteorological stations in the State of California with significant correlations (positive in red, negative in blue) between PNA and temperature. sources. This pattern shows especially high values of positive correlation in April, where 77.9% of the temperature in the stations studied seems to be affected by EPO. Moving on to the North Atlantic Oscillation (NAO) (Figure 9), the highest percentage of stations (88.4%), with positive correlations between NAO and the temperature found in April and this percentage also high in May (56.4%) and March (40.7%). In this regard, strong positive phases of NAO are associated with above-average temperatures in the southern United States including California. This is supported by another recent investigation, where a substantial link between NAO and surface air temperatures over California during the March-June period was found [91]. Lastly, we can point out that NAO might influence temperatures for five months, from March to July, throughout California. Figure 8: Percentage of meteorological stations in the State of California with significant correlations (positive in red, negative in blue) between EPO and temperature. Figure 7: Percentage of meteorological stations in the State of California with significant correlations (positive in red, negative in blue) between WPO and temperature.