Goodwood
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goodwood clear sky chart from 2005-11-06 to 2024-03-23.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
28%
23045
13%
80934
8%
22949
36%
22949
15%
57392

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
12%
754
8%
4418
3%
737
23%
737
5%
3301
January11th to 20thNight
14%
757
7%
4227
2%
740
20%
740
4%
3304
January21st to endNight
18%
832
7%
4528
6%
814
27%
814
6%
3516
February1st to 10thNight
13%
760
11%
2470
3%
760
23%
760
9%
1928
February11th to 20thNight
15%
740
12%
2405
3%
740
25%
740
11%
1801
February21st to endNight
14%
628
11%
1994
3%
628
24%
628
13%
1460
March1st to 10thNight
17%
760
15%
2090
5%
760
27%
760
16%
1522
March11th to 20thNight
19%
760
17%
2090
7%
760
28%
760
16%
1535
March21st to endNight
26%
801
19%
2201
8%
801
35%
801
21%
1533
April1st to 10thNight
20%
720
15%
1822
4%
720
27%
720
19%
1362
April11th to 20thNight
26%
669
18%
1733
6%
669
32%
669
22%
1236
April21st to endNight
27%
540
16%
1620
6%
540
34%
540
20%
1137
May1st to 10thNight
38%
527
15%
1607
9%
527
43%
527
23%
1059
May11th to 20thNight
37%
354
21%
1416
16%
354
52%
354
22%
825
May21st to endNight
48%
388
17%
1551
16%
388
59%
388
27%
832
June1st to 10thNight
39%
360
13%
1440
12%
360
51%
360
20%
859
June11th to 20thNight
41%
360
15%
1440
17%
360
51%
360
23%
830
June21st to endNight
43%
360
13%
1418
16%
360
50%
360
21%
841
July1st to 10thNight
54%
350
16%
1400
19%
350
62%
350
31%
720
July11th to 20thNight
52%
348
19%
1392
24%
348
58%
348
30%
758
July21st to endNight
56%
528
18%
1613
14%
499
61%
499
34%
930
August1st to 10thNight
56%
537
18%
1600
12%
534
61%
534
35%
956
August11th to 20thNight
61%
534
22%
1598
14%
534
67%
534
35%
916
August21st to endNight
48%
678
20%
1866
10%
678
53%
678
32%
1187
September1st to 10thNight
50%
720
17%
1800
7%
720
54%
720
33%
1183
September11th to 20thNight
50%
720
27%
1884
15%
720
56%
720
37%
1150
September21st to endNight
44%
720
20%
2027
15%
720
49%
720
26%
1332
October1st to 10thNight
36%
720
16%
2160
13%
720
42%
720
21%
1491
October11th to 20thNight
25%
720
13%
2160
6%
720
34%
720
16%
1582
October21st to endNight
20%
792
14%
2376
7%
792
29%
792
13%
1807
November1st to 10thNight
28%
740
18%
2485
12%
740
37%
740
18%
1681
November11th to 20thNight
19%
760
13%
2660
6%
760
29%
760
12%
1950
November21st to endNight
20%
760
9%
2660
6%
760
26%
760
10%
2037
December1st to 10thNight
12%
760
7%
2660
3%
760
17%
760
7%
2152
December11th to 20thNight
13%
760
7%
3256
2%
759
19%
759
6%
2580
December21st to endNight
9%
828
4%
4867
0%
817
16%
817
4%
4099

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
15%10%48%7%35%5%5%7%31%
78654
Night
15%10%48%7%45%5%5%6%31%
81198
TransparencyDay
50%8%12%19%10%1
78367
Night
50%8%12%18%10%1
81019
SeeingDay
20%16%31%21%9%3
13523
Night
20%14%32%24%9%1
23070

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
17%14%5%8%7%45%345%28%
2517
11th to 20thDay
11%17%8%14%11%45%445%17%
2708
21st to endDay
21%19%7%11%7%35%445%15%
3124
February1st to 10thDay
15%15%5%11%8%5%7%5%5%5%19%
1710
11th to 20thDay
12%15%8%10%8%45%35%6%24%
1663
21st to endDay
17%15%5%9%6%45%44425%
1457
March1st to 10thDay
14%12%49%9%35%45%5%29%
2087
11th to 20thDay
12%13%6%8%8%36%445%31%
2090
21st to endDay
19%10%37%6%45%445%34%
2200
April1st to 10thDay
19%12%47%6%445%5%7%27%
2137
11th to 20thDay
19%9%46%5%245%5%6%35%
2191
21st to endDay
20%9%37%6%3445%7%32%
2340
May1st to 10thDay
18%8%47%6%45%45%7%33%
2349
11th to 20thDay
15%8%36%5%3446%7%39%
2478
21st to endDay
12%5%26%5%46%5%5%8%41%
2725
June1st to 10thDay
16%7%45%5%35%6%5%8%36%
2520
11th to 20thDay
13%6%35%6%36%5%6%10%38%
2520
21st to endDay
15%6%35%6%36%5%5%9%37%
2520
July1st to 10thDay
10%5%245%35%5%6%9%45%
2520
11th to 20thDay
10%6%37%5%36%6%8%9%37%
2520
21st to endDay
10%5%37%8%46%7%7%10%34%
2607
August1st to 10thDay
10%6%36%6%45%5%8%9%37%
2327
11th to 20thDay
9%6%27%7%46%7%7%9%37%
2303
21st to endDay
13%6%36%5%35%6%6%8%39%
2471
September1st to 10thDay
13%5%36%5%345%7%7%41%
2160
11th to 20thDay
12%5%36%5%346%6%8%42%
2073
21st to endDay
14%6%46%7%35%45%6%39%
1931
October1st to 10thDay
19%9%47%6%35%45%7%33%
1800
11th to 20thDay
20%10%48%7%35%5%5%5%28%
1800
21st to endDay
24%14%48%6%35%45%6%22%
1980
November1st to 10thDay
15%11%48%7%35%5%5%7%31%
1588
11th to 20thDay
16%11%5%10%7%46%6%5%7%23%
1520
21st to endDay
19%14%5%9%8%46%446%20%
1520
December1st to 10thDay
16%16%7%13%9%6%6%5%5%6%13%
1520
11th to 20thDay
17%14%5%8%8%35%6%5%8%21%
1906
21st to endDay
26%17%6%12%8%5%5%43412%
2772
January1st to 10thNight
17%14%6%9%8%46%5%5%6%21%
4429
11th to 20thNight
13%13%6%13%11%5%6%5%5%6%18%
4248
21st to endNight
19%13%7%9%7%45%5%5%6%19%
4532
February1st to 10thNight
13%15%6%9%8%5%7%6%5%5%22%
2470
11th to 20thNight
14%14%6%9%7%45%5%6%6%25%
2403
21st to endNight
14%11%5%9%7%45%46%6%28%
1994
March1st to 10thNight
13%10%48%7%46%45%5%34%
2080
11th to 20thNight
14%12%5%7%7%45%44433%
2089
21st to endNight
15%9%37%6%35%45%6%37%
2201
April1st to 10thNight
20%10%46%6%3445%6%32%
1822
11th to 20thNight
16%8%37%5%445%5%6%38%
1733
21st to endNight
16%7%48%6%3445%8%34%
1620
May1st to 10thNight
17%6%35%5%35%5%5%8%38%
1607
11th to 20thNight
13%435%5%345%5%7%45%
1415
21st to endNight
10%3245%245%48%51%
1550
June1st to 10thNight
12%5%26%6%345%6%8%41%
1440
11th to 20thNight
10%5%36%6%35%5%6%9%43%
1440
21st to endNight
12%6%26%6%35%46%8%43%
1418
July1st to 10thNight
6%4245%345%5%8%54%
1440
11th to 20thNight
9%5%35%43446%8%49%
1440
21st to endNight
8%4244346%7%8%49%
1708
August1st to 10thNight
7%5%26%5%3446%8%49%
1611
11th to 20thNight
7%5%245%246%6%9%50%
1598
21st to endNight
9%5%35%6%35%5%5%6%48%
1866
September1st to 10thNight
9%6%35%6%45%5%6%7%46%
1800
11th to 20thNight
12%4245%2446%7%52%
1884
21st to endNight
15%7%35%5%3445%8%42%
2027
October1st to 10thNight
15%7%38%6%45%5%6%6%36%
2160
11th to 20thNight
19%9%37%7%445%5%6%32%
2160
21st to endNight
22%10%46%7%35%5%5%6%27%
2376
November1st to 10thNight
18%9%36%6%3445%7%35%
2485
11th to 20thNight
17%10%5%9%7%5%5%45%7%27%
2660
21st to endNight
18%13%48%7%46%5%6%6%23%
2660
December1st to 10thNight
18%14%6%10%8%45%5%5%6%17%
2660
11th to 20thNight
15%18%6%9%7%46%45%5%20%
3288
21st to endNight
27%15%5%11%7%45%445%12%
4884

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
57%8%16%12%7%1
2518
11th to 20thDay
69%7%10%10%5%
2708
21st to endDay
69%8%9%9%41
3124
February1st to 10thDay
65%7%9%14%41
1710
11th to 20thDay
59%8%9%16%7%1
1672
21st to endDay
60%7%9%16%7%1
1457
March1st to 10thDay
54%7%13%15%10%
2090
11th to 20thDay
53%7%9%17%11%2
2090
21st to endDay
51%6%9%17%15%2
2200
April1st to 10thDay
55%7%10%17%10%1
2137
11th to 20thDay
48%6%10%21%14%1
2191
21st to endDay
50%7%11%17%12%2
2340
May1st to 10thDay
50%6%9%20%13%2
2349
11th to 20thDay
43%7%10%25%15%1
2482
21st to endDay
39%8%15%23%12%2
2725
June1st to 10thDay
43%9%13%20%15%1
2520
11th to 20thDay
40%8%12%24%15%1
2520
21st to endDay
42%8%14%23%13%1
2520
July1st to 10thDay
33%9%14%25%18%2
2450
11th to 20thDay
38%10%15%27%9%1
2445
21st to endDay
40%11%15%22%12%1
2461
August1st to 10thDay
39%9%16%24%11%2
2314
11th to 20thDay
39%10%15%25%11%
2303
21st to endDay
40%8%15%25%11%1
2471
September1st to 10thDay
39%9%14%27%10%1
2160
11th to 20thDay
35%10%13%27%14%
2073
21st to endDay
44%8%14%26%8%
1931
October1st to 10thDay
49%7%13%18%11%1
1800
11th to 20thDay
56%8%12%18%6%1
1800
21st to endDay
61%7%12%13%6%1
1980
November1st to 10thDay
50%9%14%18%8%1
1588
11th to 20thDay
56%11%12%13%8%1
1520
21st to endDay
63%8%11%15%3
1520
December1st to 10thDay
67%10%10%10%3
1520
11th to 20thDay
59%12%12%12%6%
1906
21st to endDay
74%8%7%8%2
2772
January1st to 10thNight
60%10%14%11%5%
4429
11th to 20thNight
64%10%12%11%31
4248
21st to endNight
63%8%12%11%41
4532
February1st to 10thNight
60%9%10%17%5%1
2470
11th to 20thNight
56%8%11%17%8%
2405
21st to endNight
54%7%13%18%8%1
1994
March1st to 10thNight
50%8%13%19%9%2
2090
11th to 20thNight
52%6%9%20%10%2
2090
21st to endNight
46%7%9%20%15%2
2201
April1st to 10thNight
52%6%9%19%13%1
1822
11th to 20thNight
47%6%9%20%17%2
1733
21st to endNight
47%7%11%18%15%2
1620
May1st to 10thNight
44%6%11%21%16%3
1607
11th to 20thNight
38%6%10%24%18%4
1416
21st to endNight
32%6%16%24%18%4
1551
June1st to 10thNight
39%8%11%24%16%2
1440
11th to 20thNight
37%7%11%22%21%2
1440
21st to endNight
39%7%14%24%16%1
1418
July1st to 10thNight
27%8%13%28%23%3
1400
11th to 20thNight
31%7%13%31%17%1
1392
21st to endNight
29%8%15%31%15%2
1613
August1st to 10thNight
32%7%19%28%13%1
1600
11th to 20thNight
29%7%17%32%14%1
1598
21st to endNight
34%9%13%28%14%2
1866
September1st to 10thNight
35%8%16%26%14%1
1800
11th to 20thNight
31%6%12%32%17%1
1884
21st to endNight
40%7%13%27%12%
2027
October1st to 10thNight
45%8%12%20%15%1
2160
11th to 20thNight
51%9%13%20%7%
2160
21st to endNight
55%9%11%15%10%
2376
November1st to 10thNight
46%8%12%21%11%1
2485
11th to 20thNight
54%9%12%14%9%1
2660
21st to endNight
56%11%16%13%4
2660
December1st to 10thNight
64%9%12%12%4
2660
11th to 20thNight
63%9%10%13%4
3288
21st to endNight
71%9%10%8%3
4884

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
23%24%29%18%6%
180
11th to 20thDay
23%31%26%15%31
232
21st to endDay
24%25%36%13%2
297
February1st to 10thDay
27%27%31%12%3
270
11th to 20thDay
24%27%40%8%1
270
21st to endDay
35%23%34%8%
252
March1st to 10thDay
24%22%36%15%3
460
11th to 20thDay
24%23%33%17%31
460
21st to endDay
31%19%30%15%41
470
April1st to 10thDay
26%20%34%13%6%
420
11th to 20thDay
28%20%25%17%7%3
412
21st to endDay
26%16%36%14%7%1
420
May1st to 10thDay
23%14%31%20%8%4
423
11th to 20thDay
18%16%30%24%7%4
447
21st to endDay
15%12%29%27%13%4
485
June1st to 10thDay
16%14%32%28%9%1
450
11th to 20thDay
15%15%28%27%13%2
450
21st to endDay
19%8%33%27%11%2
450
July1st to 10thDay
9%8%26%34%18%4
445
11th to 20thDay
14%7%27%31%15%7%
444
21st to endDay
8%8%35%33%11%6%
488
August1st to 10thDay
11%8%26%32%15%8%
446
11th to 20thDay
13%8%23%28%22%7%
439
21st to endDay
13%10%29%25%16%7%
495
September1st to 10thDay
12%10%28%28%15%8%
450
11th to 20thDay
10%8%28%24%18%11%
450
21st to endDay
15%12%29%26%12%6%
450
October1st to 10thDay
22%13%28%17%17%3
450
11th to 20thDay
22%22%32%17%6%1
450
21st to endDay
29%21%28%17%5%
495
November1st to 10thDay
23%23%31%16%7%1
255
11th to 20thDay
23%26%32%15%41
180
21st to endDay
24%26%39%10%2
180
December1st to 10thDay
24%22%36%13%41
180
11th to 20thDay
31%21%33%12%31
180
21st to endDay
30%22%36%12%1
198
January1st to 10thNight
23%23%36%13%5%
760
11th to 20thNight
28%17%33%18%41
760
21st to endNight
20%16%37%21%6%
836
February1st to 10thNight
21%21%38%18%2
760
11th to 20thNight
23%19%36%19%3
743
21st to endNight
22%21%37%15%4
628
March1st to 10thNight
20%20%37%19%3
760
11th to 20thNight
21%20%36%17%41
760
21st to endNight
20%15%33%25%6%
801
April1st to 10thNight
25%17%34%22%3
720
11th to 20thNight
18%18%35%20%8%1
669
21st to endNight
20%14%34%24%9%
540
May1st to 10thNight
20%9%28%30%11%2
527
11th to 20thNight
18%8%32%29%13%1
354
21st to endNight
11%8%28%35%17%1
389
June1st to 10thNight
13%8%31%36%12%
360
11th to 20thNight
12%8%30%36%14%1
360
21st to endNight
14%6%30%37%13%1
360
July1st to 10thNight
7%6%27%39%20%1
350
11th to 20thNight
12%329%34%20%1
348
21st to endNight
10%326%41%18%2
528
August1st to 10thNight
10%421%36%27%2
537
11th to 20thNight
7%419%43%24%3
534
21st to endNight
12%5%28%34%19%3
678
September1st to 10thNight
12%8%25%34%18%4
720
11th to 20thNight
13%8%24%30%21%5%
720
21st to endNight
17%9%23%31%16%4
720
October1st to 10thNight
19%8%30%26%15%2
720
11th to 20thNight
23%16%32%21%7%1
720
21st to endNight
28%15%31%22%31
792
November1st to 10thNight
24%13%32%23%8%1
740
11th to 20thNight
22%19%32%19%6%1
760
21st to endNight
25%18%30%21%5%
760
December1st to 10thNight
28%18%35%16%3
760
11th to 20thNight
21%20%37%18%31
760
21st to endNight
30%17%36%15%2
836
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