|
Chepstow Climate Station |
Extreme Weather
Averages
Element Frequency
Covering
Years
2004-2012
Notes on recording of elements
All averages are in Days per Month.
There is one exception to this under the heading of Storms.
This additional category will deal with number of
recorded thunderstorms/hailstorms at or near the site on a per occasion basis.
Elements are observed on a midnight-to-midnight
parameter with exception of Snow
Lying and Ice Days.
These elements are observed/recorded at or between
0900 hours.
Snow lying requires 50% or more of snow cover on the
ground, while an Ice day requires the temperature to be below 0.0c for the
24-hours between 0900-0900 GMT.
The category under Hail will include all types of formation less than and
greater than 5mm.
Annual averages/totals are derived from all 12 months
combined.
Please note that some elements will
have shorter-term averages due to their start date.
Therefore calculations may give rise
to small anomalies over lesser years. Refer to table below for commencement
dates.
|
Element |
General
Requirement |
Commencement |
Element |
General
Requirement |
Commencement |
||
|
Air Frost |
Air Temperature to fall to -0.1c |
July |
2004 |
Snow Lying |
Snow measured @0900 in Cm |
July |
2004 |
|
Grass Frost |
Ground temperature to fall to -0.1c |
July |
2004 |
Hail |
All types recorded in Mm |
July |
2004 |
|
Fog |
Visibility <1000m |
December |
2004 |
Thunder Heard |
Audible Thunder heard from site |
July |
2004 |
|
Mist |
Visibility >1000m |
December |
2004 |
Storms |
Number of Storms at or near site |
July |
2004 |
|
Gale |
Gust speeds reaching =>39mph |
June |
2005 |
Ice
Day |
Air temperature <0c for 24hrs (9-9am) |
July |
2004 |
|
Snow Falling |
Sleet or Snow observed falling |
July |
2004 |
|
|
|
|
Monthly and
Annual averages
Note that the annual average is a rolling average and is re-calculated
every month.
Tables updated on: 1st May 2012.
|
ELEMENT |
JAN |
FEB |
MAR |
APR |
MAY |
JUN |
JUL |
AUG |
SEP |
OCT |
NOV |
DEC |
ANNUAL |
|
Air Frost |
7.2 |
7.2 |
2.8 |
0.7 |
|
|
|
|
|
0.1 |
2.7 |
8.0 |
29.6 |
|
Grass Frost |
15.2 |
13.2 |
9.5 |
3.3 |
0.1 |
|
|
|
|
1.1 |
7.6 |
16.0 |
67.6 |
|
Fog |
2.3 |
2.1 |
2.2 |
0.5 |
0.4 |
0.2 |
0.2 |
0.5 |
0.8 |
1.8 |
4.5 |
2.8 |
19.1 |
|
Mist |
6.5 |
8.8 |
7.0 |
6.3 |
5.2 |
5.0 |
3.1 |
2.5 |
8.3 |
9.7 |
8.1 |
8.8 |
80.2 |
|
Gale |
0.4 |
0.2 |
0.8 |
0.1 |
0.5 |
|
|
|
|
|
0.4 |
0.2 |
2.8 |
|
Snow Falling |
2.7 |
4.2 |
1.5 |
0.5 |
|
|
|
|
|
|
0.7 |
2.6 |
12.6 |
|
Snow Lying |
1.5 |
1.0 |
0.1 |
|
|
|
|
|
|
|
0.2 |
2.1 |
5.1 |
|
Hail |
1.2 |
0.8 |
1.6 |
1.1 |
0.8 |
0.1 |
0.4 |
0.3 |
0.2 |
0.1 |
0.7 |
1.1 |
8.9 |
|
Thunder Heard |
|
0.1 |
0.1 |
0.6 |
1.4 |
0.8 |
1.5 |
1.7 |
0.4 |
0.2 |
0.1 |
0.5 |
7.4 |
|
Storms |
|
0.1 |
0.1 |
0.6 |
1.5 |
1.4 |
2.2 |
2.0 |
0.6 |
0.3 |
0.1 |
0.6 |
9.4 |
|
Ice Day |
0.2 |
|
|
|
|
|
|
|
|
|
0.1 |
0.7 |
1.1 |
Current running totals
|
ELEMENT |
JAN |
FEB |
MAR |
APR |
MAY |
JUN |
JUL |
AUG |
SEP |
OCT |
NOV |
DEC |
TOTAL |
MONTHS |
|
Air Frost |
58 |
58 |
23 |
6 |
|
|
|
|
|
1 |
22 |
64 |
232 |
94 |
|
Grass Frost |
122 |
106 |
76 |
27 |
1 |
|
|
|
|
9 |
61 |
128 |
530 |
94 |
|
Fog |
19 |
17 |
18 |
4 |
3 |
2 |
2 |
4 |
6 |
13 |
32 |
23 |
142 |
89 |
|
Mist |
52 |
71 |
56 |
51 |
37 |
35 |
22 |
18 |
57 |
68 |
57 |
71 |
595 |
89 |
|
Gale |
3 |
2 |
6 |
1 |
3 |
|
|
|
|
|
3 |
2 |
20 |
83 |
|
Snow Falling |
22 |
34 |
12 |
4 |
|
|
|
|
|
|
6 |
21 |
99 |
94 |
|
Snow Lying |
12 |
8 |
1 |
|
|
|
|
|
|
|
2 |
17 |
40 |
94 |
|
Hail |
10 |
7 |
13 |
9 |
6 |
1 |
3 |
3 |
2 |
1 |
6 |
9 |
70 |
94 |
|
Thunder Heard |
|
1 |
1 |
5 |
10 |
6 |
11 |
14 |
3 |
2 |
1 |
4 |
58 |
94 |
|
Storms |
|
1 |
1 |
5 |
11 |
10 |
16 |
16 |
5 |
3 |
1 |
5 |
74 |
94 |
|
Ice Day |
2 |
|
|
|
|
|
|
|
|
|
1 |
6 |
9 |
94 |
Copyright ©Nick Felstead 2004-2012