The average daily temperature is around 20 degrees Celsius in the beginning of September and cools down to an average of 19 degrees Celsius by the end of the month. In September the average high is a balmy 23 degrees Celsius with an average low of 16 degree Celsius. The highest recorded temperature during September, in recent years was 36 degrees Celsius and the lowest recorded temperature was a very cold 2 degrees Celsius. The nights are getting cooler so you may want to pack a light sweater if you plan on heading out in the evening.

The average relative humidity in September is around 71%.

Puerto de la Cruz experiences an average of 4.5mm of rain spread out over 4 days. This is the last very dry month of the year in which to visit the resort town. The end of September and going into October sees the start of the rainy months. If you want a higher chance of dry days, you should time you visit to the beginning of September.

September sees the average daily sunshine hours drop to 10 from the August high of 11. You will still have plenty of sunny hours to explore the beaches and town.  This is a popular month for golfing holidays as there are still plenty of hours of sunshine, the weather is still dry but the days tend to be cooler.

Wind speeds for the month average around 18km/h or 12mph. The highest recorded sustained wind speed in September was 85km/h or 53mph.

The resort is affected by foggy conditions on nine days on average during September. The fog is usually fairly light and clears quickly.

The sea temperatures in September are the highest on average for the year. The average sea temperature is very warm 24 degrees Celsius. This should be warm enough for even the most reluctant of swimmers.

Source: http://www.holiday-weather.com/