September 2025 Weather Outlook. Fall 2025 is forecast to be warmer than average for most in the u.s. The meteorological autumn spans the period from 1st september to 30th november.
Week 1 (monday 23 september to sunday 29 september) an unsettled week is signalled for week 1 with low pressure dominating bringing in a cold northerly airflow at times. Our long range forecast (which is updated on a daily basis) provides an indication of how the weather might change, or be different from normal, (i.e.