The highest day temperature in September 2025 was 90°F. The lowest night temperature was 51°F. The average values for day and night temperatures during September were 77.4°F и 62.6°F respectivly.

The average sea surface temperature in September 2025 for St Constantine and Helena was 77.4°F. The maximum and minimum values were 72.0°F and 80.4°F respectively.

Most of the days in September are sunny but you can also expect cloudy and gloomy days.

Precipitation total in September for St Constantine and Helena is 0.7 in. It makes september one of the least rainy months of the year.

The average wind speed in September is 10.2 mph.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for St Constantine and Helena in September is 9.7 hours.