September, October and November are the meteorological fall months. And looking at the temperature data for those months back to 1938 at Albany, which is when observations began at the present climate reporting site at the Albany airport, we find that over half, 53%, or 19 of the 36 months in the record through 2023, that have landed in the top 10 for warmest, have all occurred recently since 2000.
This data illustrates the impact the warming climate is having on our falls with the frequency of very warm fall months steadily rising beyond what would typically be expected through natural random occurrence. The same dataset also shows no fall months at Albany (since 1938) landing in the top 10 for coldest in the same 23 year period since 2000.
In a normal or stable climate, very warm months would be balanced out by very cold ones with both the cold and warm extremes occurring infrequently. Today, the cold extremes are now quite rare compared to the high frequency of warm extremes all made possible by the warm climate shift due largely to greenhouse gas emissions steadily warming both the atmosphere and the oceans.
Top 10 Warmest September's on Record at Albany - Monthly Mean Temperature (since 1938) Through 2023
Top 10 Warmest October's on Record at Albany - Monthly Mean Temperature (since 1938) Through 2023
Top 10 Warmest November's on Record at Albany - Monthly Mean Temperature (since 1938) Through 2023
The autumn warmth we're now routinely observing here in the Capital Region is also happening across the country and the globe. Our partners at Climate Central analyzed temperature data for 242 cities across the lower 48 and found that since 1970, 234 of those cities, or 97%, have had increases in their average fall temperatures with those mean temperatures rising by an average of 2.5 degrees F. And more than a third (84) of the cities studied had a 3.0 degree or higher increase in the average fall temperature with warming through the season in all parts of the nation.
In fact locally, autumn is the second fastest warming season behind winter, with the season on average now 3.5 degrees F warmer than in 1970 in the Capital Region, with of course quite a bit of year to year variability due to natural differences in weather patterns from season to season. That year to year variability, which is an illustration of the weather, is shown on the graph below by the jagged line which connects each year's fall season average temperature data plot. The straight line on the graph is the trend line which fits each data point and represents the climate. This trend line shows the sharp and rapid upward trend in temperature over time showing that cold autumns are becoming progressively less cold over time and our warm falls are getting warmer. (NOTE: The last big dip on the graph is the 2020 data point which was impacted by the instrumentation error at the Albany observation site at the airport that created an artificial cold bias in the fall 2020 data.)
The warming has resulted in fourteen more warmer than average days per fall since 1970 at Albany, which is a significant increase over a short period of time.
Science has confirmed that the cause of modern day warming is largely due to anthropogenic (human induced) activities chiefly through greenhouse gas emissions, with carbon dioxide (CO2), the prime pollutant. CO2 is now at levels higher than anytime in the past 800,000 years, with past fluctuations in concentrations, and subsequent changes in the climate, due to natural variability occurring over thousands of years. The graph below illustrates the rapid and dramatic increase in observed CO2 since the start of the industrial revolution, which had lead to the very rapid recent warming of the climate, faster than anytime in the long term record before humans even existed.
This graph illustrates the relationship between the global upward temperature trend and the steady increase in atmospheric carbon dioxide with observations taken since 1880.
Another way to observe the warming through the fall as well as in the winter, spring, and summer, specifically at Albany, is by looking at the change in temperature that's been observed going from the 1981-2000 climate normal data set to the new 1991-2020 climate data normal set which was released in May 2020. Average monthly and seasonal temperatures are up across board meaning our seasons now have a new "Normal."
For a look at how and why "Normals" are calculated, what they're used for, and why new ones are released every ten years, click on the article line "What The New Normal Means When It Come to The Weather."
NOAA's Climate Prediction Center (CPC) issues weekly, monthly, and seasonal probabilistic forecasts for temperature and precipitation meant to depict whether the most likely average weather conditions for the particular period of time will be below average, average, or above average. In the case of the fall season forecast we're looking at the mostly likely average temperature and rainfall conditions for the combined three month September, October, and November period.
This type of forecast, being such long term, however, does not say anything about shorter term weather variability within the season that can produce periods of much cooler, much warmer, drier, or much wetter than typical conditions, with those extremes over the longer three month period being smoothed out in the final average.
Forecast confidence for this fall (2024) throughout the Northeast is high for warmer than normal conditions to prevail, which would be a continuation of the warmth that's been in place through the year. This forecast, however, does not mean it's going to be warm all of the time. Cold shots are likely, as is typical in the fall. But it is likely the colder periods will be less cold than typical and last for shorter periods of time than in the past with warmer than average days more than likely outnumbering colder than average ones over the three months period throughout the Northeast.
For precipitation, which certainly could include some snow toward the end of the season, the lean across the area is for wetter than average conditions, although the forecast probability is not particularly high for that outcome, which is why I use the term "Lean." The wildcard, especially early in the season will be the tropics which are forecast by NOAA to be active and could push the risk for wetter than average conditions higher should any system send tropical moisture into the Northeast.