September 2025 saw drier conditions for the month on Grandfather Mountain, according to data recorded at the park’s official weather reporting stations.
The weather station near the Swinging Bridge reported 4.25 inches of precipitation in September 2025. Precipitation at the top of the mountain includes rain and the liquid equivalent of any frozen precipitation (when applicable). This is the 23rd driest September in Grandfather’s 69 years of weather recording. The lowest monthly precipitation total for September is .68 inches in 2019.
Observations recorded near the park’s Wilson Center for Nature Discovery totaled 4.95 inches of precipitation for the month. Precipitation is also measured at the latter location, as high winds can make it difficult to record accurate observations at the top.
The mountain’s rainiest September was recorded in 2004, when 32.3 inches were observed near the bridge.
There were 21 days of at least trace amounts of recorded liquid precipitation (rain and the liquid equivalent of frozen precipitation, when applicable) for September 2025. The record number of days for the month of September is 23 days, observed in 2020 and 2024.
The day with the highest amount of this precipitation observed was Sept. 27, when 1.10 inches were recorded at the top. The day with the highest amount of precipitation observed on record for September was Sept. 8, 2004, when the weather station noted 11.3 inches. Data from 2024’s Hurricane Helene is not taken into account for this record as staff were not able to record precipitation measurements in the immediate aftermath of the storm.
The average high temperature for September 2025 was 60.65 degrees Fahrenheit, with an average low of 51.55 degrees and a mean of 56.1 degrees. The 69-year average high temperature for the mountain is 63.18 degrees, the 69-year average low temperature is 50.99 degrees and the historic average mean is 57.07 degrees.
The warmest temperature recorded was 67.6 degrees on Sept. 5, just over 11 degrees shy of the mountain’s record September high of 79 degrees, observed Sept. 24, 2010.
Generally, September sees fall weather conditions take hold on Grandfather Mountain, with cooler temperatures arriving. Sept. 9 saw the coldest temperature recorded with 40.8 degrees. The lowest temperature ever observed on Grandfather Mountain in the month of September (not counting wind chill) was 24 degrees on Sept. 30, 1967.
The weather station on the Mile High Swinging Bridge did not note any days in September with a wind gust higher than 60 mph. The highest gust ever recorded on Grandfather Mountain was 124 mph, observed Feb. 25, 2019.
Weather Reporting
The Grandfather Mountain Stewardship Foundation records and reports data in two different ways:
- The park maintains an automated weather station at the top of the Mile High Swinging Bridge. The N.C. State Climate Office assists the foundation in calibrating the machines and ensuring overall accuracy of data.
- Grandfather Mountain has been an active member of the National Oceanic and Atmospheric Administration’s (NOAA) Cooperative Observer Program since 1955 by reporting weather data from locations near the Mile High Swinging Bridge and the Nature Museum (now the Wilson Center for Nature Discovery).
- In the 69 years of weather collection at Grandfather Mountain, instrument locations for the Top Shop and Swinging Bridge area have moved around slightly as technology and understanding of what makes the best location for reporting have improved.
For more information on weather at Grandfather Mountain, visit www.grandfather.com/weather.