La Palma lies in both the cool northeasterly Canary Current and the northerly trade winds, giving it a sunny climate with year-round moderate temperatures. The sea level climate is Atlantic, with temperatures varying rather little during the year. The average temperature at sea level is approximately 22 C in August and 15 C in January. The average temperature at the Roque is approximately 18 C in summer, 3 C in winter, with a typical daily range of 7 C. Precipitation occurs almost entirely in the winter months (October--April), with snow and ice being common between January and March. Rarely, snowstorms can cause drifts of one metre or more. In the worst conditions there may be delays of several hours or even days in reaching the site while roads are closed.
La Palma occasionally comes under the influence of winds from the Sahara (see La Palma Technical Note 41), bringing very fine clouds of dust in suspension. The months most affected are July and August.
Warm clothing is advisable in all seasons. Lip balm and sunglasses are strongly recommended for the mountain top because of the low humidity and amount of glare from sunlight.