Stornoway weather in September 2026: wetter than average, mild nights, and a warm spell mid-month

September 2026 in Stornoway was wetter than the long-term average, with temperatures a touch above normal and a notable warm spell in the third week of the month.

Rainfall finished around 144 mm against a 1991–2020 September average of about 104 mm for Stornoway Airport — roughly 40% more than usual. The mean temperature sat a little above the climate normal, nights stayed relatively mild for the time of year, and the month produced one of the warmer days of early autumn.

The month in numbers

The rain was spread through the month rather than concentrated in a single storm. Several days in the first week produced 8–16 mm, and another wet spell arrived around the 24th–25th. A few quieter days appeared in the second half of the month, but overall it was a wetter September than the long-term average.

A wet first half

The opening days set the tone. The 2nd brought around 10 mm, the 5th was the wettest single day with roughly 16 mm, and the 6th and 7th each added close to 10 mm. South-westerly and westerly flows dominated, keeping the ground soft and the burns running. By mid-month the cumulative rainfall was already well ahead of the seasonal normal.

A warm spell mid-month

The standout temperature of the month came on the 21st, when the maximum reached 18.5 °C. That is a notably warm day for late September in Stornoway and sits well above the long-term mean daily maximum. The 22nd followed with another mild day, and several other dates in the third week produced maxima in the mid-teens. Clearer spells between fronts allowed the air mass to warm under the still-relatively high sun.

Cooler nights and a late-month dip

The coldest night was the 23rd, when the minimum fell to 6.6 °C. The 13th and 24th also produced minima close to 7 °C. Nothing exceptional for the season, but enough to mark the shift toward autumn after the milder nights of August. The final days of the month mixed further rain with a couple of drier interludes, including a dry 26th and 28th in the available records.

Mild overall for 58°N

A mean temperature a few tenths of a degree above the 1991–2020 normal is consistent with the recent run of mild Septembers on the west coast. Sea surface temperatures around the Western Isles remain relatively high into early autumn, so a south-westerly airstream continues to deliver mild air even as daylight shortens. The wind still matters more than the thermometer for comfort on exposed ground.

What October usually brings

October is typically a step wetter and a little cooler. Stornoway Airport averages around 12.0 °C by day and 7.0 °C at night, with about 133 mm of rain over roughly 20 wet days. The first named storms of the season often appear in this window. The October 2026 summary is already available for comparison, and the Isle of Lewis weather warnings page explains what each warning colour means before one is issued.

For day-to-day planning, the Stornoway weather and 7-day forecast carries the current outlook.

How this was put together

Figures are drawn from station and reanalysis summaries for Stornoway (approximately 58.21°N, 6.32°W) together with the Met Office 1991–2020 long-term averages for Stornoway Airport, reproduced in the climate table on the weather page. Where daily sources differ slightly, totals are presented as approximate. Sunshine is not compared directly because the observing methods are not identical.