| Remarks | Max | Min | Rain | ||||
| 1st | Dry with frequent sunny spells. Brisk north-westerly breeze. | 20.6 | C | 13.8 | C | _ | |
| 2nd | Sunshine through the morning, clouding over later. Moderate rain for a time during the evening. | 20.4 | C | 11.6 | C | 2.7 | mm |
| 3rd | Dry with prolonged spells of sunshine. | 18.0 | C | 10.6 | C | _ | |
| 4th | Cool start, but sunshine breaking through. Becoming warm by late afternoon. | 18.4 | C | 9.0 | C | _ | |
| 5th | Overcast and rather hazy to begin with. | 21.3 | C | 13.0 | C | _ | |
| 6th | Cloudy and humid with brief sunny spells, sunshine becoming more prolonged towards evening. | 23.5 | C | 13.3 | C | _ | |
| 7th | Mist clearing quickly and then some prolonged spells of practically unbroken sunshine. Warm. | 21.5 | C | 13.0 | C | _ | |
| 8th | Early sunshine, but clouding over fairly quickly and remaining overcast throughout the day. | 16.5 | C | 11.1 | C | _ | |
| 9th | Largely cloudy, although some breaks appearing. Turning warm by the afternoon. | 20.5 | C | 11.1 | C | tr | mm |
| 10th | Fresh breeze and overcast to begin with. Sunny spells breaking through later. | 20.0 | C | 13.0 | C | _ | |
| 11th | Chilly start, but warming up quickly with prolonged sunny spells through the day. | 19.4 | C | 7.8 | C | _ | |
| 12th | Early mist and low cloud clearing to fine sunny spells. Becoming warm. | 21.9 | C | 10.9 | C | _ | |
| 13th | Patches of shallow fog, but good sunshine from the start. Becoming warm later. | 22.5 | C | 8.9 | C | _ | |
| 14th | Sunshine to begin with, then clouding over with patchy outbreaks of light rain. Sunshine returning for the afternoon. | 18.0 | C | 11.4 | C | tr | mm |
| 15th | Warm for mid-September. Winds mostly light or calm with prolonged unbroken sunshine. | 20.0 | C | 7.4 | C | _ | |
| 16th | Cloudy start, sun breaking through later. Light shower late evening. | 20.0 | C | 9.0 | C | 0.1 | mm |
| 17th | Cloudy through the morning, sunshine breaking through during the afternoon. Showers through the evening. | 15.3 | C | 9.9 | C | 1.5 | mm |
| 18th | Chilly start with clear skies. Prolonged spells of sunshine, but remaining cool. | 14.8 | C | 4.5 | C | tr | mm |
| 19th | Sunny spells. Light shower early morning. Heavier showers through the evening. | 18.3 | C | 7.4 | C | 1.6 | mm |
| 20th | Occasional showers through the morning. Brighter sunnier spells during the afternoon. | 18.9 | C | 12.6 | C | 0.7 | mm |
| 21st | Dry start. Freshening south-westerly. Heavy rain during evening. | 18.0 | C | 12.1 | C | 5.0 | mm |
| 22nd | Mostly dry. Light shower during the early morning. Overcast. | 18.8 | C | 12.4 | C | 0.1 | mm |
| 23rd | Sunny spells. Freshening wind. Showers, some heavy, by evening. | 19.6 | C | 11.3 | C | 8.6 | mm |
| 24th | Heavy rain and strong winds clearing to sunny spells. Tornado reported in Northampton. | 16.1 | C | 10.9 | C | 0.6 | mm |
| 25th | Calmer start to the day with early sunshine. Freshening wind. Heavy & thundery showers through the afternoon. | 15.0 | C | 8.0 | C | 11.3 | mm |
| 26th | Fresh northerly breeze. Rather cloudy with hazy sunshine. Cold | 12.0 | C | 5.6 | C | _ | |
| 27th | Chilly start and staying cold. Frequent showers and longer spells of rain. | 12.7 | C | 5.4 | C | 2.9 | mm |
| 28th | Not quite so cold to begin with. Some sunny spells, but frequent outbreaks of rain especially later. | 13.0 | C | 9.2 | C | 3.1 | mm |
| 29th | Overcast and damp to start, sunny spells breaking through later but threatening rain all the while. | 16.5 | C | 11.1 | C | tr | mm |
| 30th | Cool, but some good spells of sunshine. | 14.2 | C | 5.1 | C | tr | mm |