Geneva has a temperate oceanic climate ("Cfb" in the Köppen climate classification). Winters are cool and generally a little cloudy. During the winter, it is possible to have several days without thawing, and a day or two with severe freezes where the thermometer displays -10 °C. There are several days each month when, if anticyclonic conditions are stable, the clouds may stay for several days. From March, with temperatures rising it feels like summer in late May. However, the rain intensifies and often has a stormy character during the month of May. These may be short but strong storms depositing several centimetres of rain within just a few minutes. Summers are often hot and rather humid, although some may be more changeable, the mornings remain relatively fresh. During the summer season, the rains are less frequent but more intense. This is the season where you most likely get thunderstorms with hail. If the weather in early September is still hot, it cools down quickly to become really cold in November. The morning frosts are then reappearing. Autumn is also the season of mists, and the month of October is often the month with the most fog in the year. The fog can be very intense, restricting vision to less than 100 m in the areas outside the city.