September 1998
On Fair Isle a dry (59.0%), mild (+0.9° Celsius) and dull (68.5%) month – with summer attempting to make a rather belated appearance.Across Scotland temperatures were typically 1.5° Celsius above average. With winds often from a south-easterly quarter eastern coasts suffered from low cloud, but the west was drier and brigter with less than 50% average rainfall. Tiree recorded its driest September since 1933.
With low pressure more or less stationary to the west of the British Isles during the first ten days, persistent SE’ly winds brought mainly cloudy conditions and temperatures slightly above average. While weather systems did move north across the UK these - due to high pressure across Scandinavia - were generally weak affairs by the time they reached the Northern Isles.
After the 11th, as low pressure transferred north-east across Scotland, temperatures fell as cooler and showery NW’ly winds spread down across the British Isles. Light winds across the North resulted in a cold night, with the temperature on the grass falling to –1.2° Celsius by the morning of the 12th.
The cool NW’lies then persisted for the next few days and, while leading to a showery period, did at least result in some sunny spells. The 17th saw a ridge of high pressure swing east across Scotland as an anticyclone to the south-west of the British Isles transferred north-east into the North Sea.
With E’ly winds off Scandinavia and a short sea-track, a warm, dry and sunny spell then followed in the Northern Isles. The temperature rose to 18° Celsius on the 21st – not only the warmest day of the year, but also the warmest September day and the 8th highest temperature ever recorded on Fair Isle! The temperature reached 27° Celsius at Aboyne and 23° Celsius at Kirkwall and Colonsay.
The milder conditions lasted until the end of the month, although the warm – if not hot - sunny conditions soon came to an end, as the high slipped away into Eastern Europe and winds again settled into the SE as low pressure moved towards Biscay. A cold front, moving down from the north and becoming slow-moving across Fair Isle, became a rather troublesome warm front as low pressure over the South-West fed moist air northwards - resulting in the month’s wettest day on the 27th.
 | Daily Data |
| Weather Diary |
1998 |
Day |
1974-97 |
1998 |
Day |
1974-97 |
|||
Mean Maximum Temperature |
12.8 |
12.1 |
Highest Max temp |
18.0 |
21 |
15.9 |
||
Mean Minimum Temperature |
10.1 |
9.0 |
Lowest Min temp |
3.7 |
12 |
1.4 |
||
Mean Sea Temperature |
12.3 |
11.8 |
Lowest grass minimum |
-1.2 |
12 |
-2.6 |
||
30 cm Earth temperature |
11.8 |
11.2 |
Days with ground frost |
1 |
1.1 |
|||
100cm Earth temperature |
11.4 |
11.0 |
Days with air frost |
0 |
0.0 |
|||
Total Rainfall (mm) |
53.6 |
90.8 |
Days with snow/sleet |
0 |
0.3 |
|||
Wettest Day (mm) |
18.9 |
27 |
16.2 |
Days with snow cover at 09hr |
0 |
0.0 |
||
Rain Days (> 0.1mm) |
19 |
21.5 |
Days with hail |
0 |
2.0 |
|||
Wet Days (> 0.9mm) |
11 |
16.5 |
Days with fog during 24hrs |
13 |
6.0 |
|||
Total sunshine, hrs |
81.1 |
118.4 |
Days with fog at 09hrs |
6 |
1.3 |
|||
Sunniest day, hrs |
10.8 |
21 |
10.4 |
Days with NIL sun |
15 |
5.6 |
||
Mean wind speed, kts |
12.1 |
15.4 |
Days with gale |
0 |
3.5 |
|||
Maximum gust, kts |
43 |
2 |
56.4 |
Days with thunder |
0 |
0.3 |
||
Mean Sea Level pressure |
1008.9 |
1010.3 |
Days with aurora |
1 |
3.3 |
|||
Wind Direction (%) North |
10.0 |
10.9 |
Wind Direction (%) S. West |
3.3 |
15.0 |
|||
at 09 hr N. East |
10.0 |
6.2 |
at 09 hr West |
10.0 |
20.2 |
|||
East |
16.7 |
8.8 |
N. West |
6.7 |
10.5 |
|||
S. East |
30.0 |
13.2 |
||||||
South |
13.3 |
14.1 |
CALM |
0.0 |
1.4 |
Weather Diary - September 1998
- To be uploaded later
Return to Weather Index