Windsor Castle Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Windsor Castle Park clear sky chart from 2005-11-06 to 2024-01-13.

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
40%
23792
14%
74634
8%
23744
46%
23744
14%
55791

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
25%
757
15%
2531
6%
757
36%
757
13%
1876
January11th to 20thNight
25%
732
13%
2378
6%
732
34%
732
10%
1864
January21st to endNight
25%
792
16%
2574
7%
792
37%
792
13%
1926
February1st to 10thNight
23%
720
13%
2340
4%
720
33%
720
12%
1765
February11th to 20thNight
16%
700
14%
2150
5%
700
27%
700
12%
1649
February21st to endNight
22%
592
18%
1776
7%
592
35%
592
13%
1355
March1st to 10thNight
29%
720
17%
2029
7%
720
39%
720
17%
1479
March11th to 20thNight
24%
720
13%
1980
6%
720
32%
720
13%
1547
March21st to endNight
24%
792
13%
2127
6%
792
31%
792
13%
1676
April1st to 10thNight
25%
720
14%
1800
3%
720
32%
720
17%
1398
April11th to 20thNight
33%
711
19%
1775
6%
711
39%
711
21%
1323
April21st to endNight
33%
720
15%
1800
6%
720
37%
720
19%
1386
May1st to 10thNight
34%
720
11%
1800
3%
720
38%
720
15%
1434
May11th to 20thNight
44%
473
12%
1534
7%
473
49%
473
11%
1203
May21st to endNight
58%
388
14%
1550
15%
388
60%
388
12%
1132
June1st to 10thNight
58%
360
13%
1440
15%
360
59%
360
13%
1020
June11th to 20thNight
60%
360
11%
1440
12%
360
62%
360
11%
1076
June21st to endNight
61%
360
12%
1440
14%
360
64%
360
12%
1065
July1st to 10thNight
63%
350
11%
1400
13%
350
65%
350
11%
1041
July11th to 20thNight
73%
495
11%
1539
10%
495
74%
495
17%
1141
July21st to endNight
63%
591
10%
1672
7%
558
65%
558
14%
1321
August1st to 10thNight
65%
537
8%
1600
6%
534
65%
534
16%
1225
August11th to 20thNight
59%
690
11%
1754
7%
690
60%
690
15%
1405
August21st to endNight
62%
792
8%
1980
4%
792
62%
792
15%
1597
September1st to 10thNight
62%
720
18%
1800
12%
720
64%
720
20%
1377
September11th to 20thNight
58%
720
18%
1800
14%
720
60%
720
19%
1381
September21st to endNight
45%
720
12%
2038
9%
720
48%
720
13%
1600
October1st to 10thNight
52%
720
16%
2160
14%
720
56%
720
16%
1607
October11th to 20thNight
44%
720
17%
2160
13%
720
51%
720
15%
1628
October21st to endNight
43%
792
17%
2376
12%
792
50%
792
16%
1758
November1st to 10thNight
42%
740
17%
2287
12%
740
50%
740
17%
1644
November11th to 20thNight
37%
760
16%
2470
11%
760
44%
760
14%
1826
November21st to endNight
42%
760
15%
2545
12%
760
49%
760
14%
1892
December1st to 10thNight
29%
760
14%
2660
6%
760
40%
760
12%
1985
December11th to 20thNight
31%
760
16%
3175
8%
759
42%
759
11%
2247
December21st to endNight
31%
828
11%
4754
7%
817
42%
817
8%
2942

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
13%6%25%5%35%5%6%8%43%
74664
Night
14%6%25%5%345%5%7%44%
75074
TransparencyDay
26%38%8%15%12%2
74378
Night
26%37%8%15%12%3
74879
SeeingDay
17%11%26%25%16%5%
14098
Night
17%8%28%32%14%2
23807

By Month

Percentage Cloud Cover SE (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
16%6%25%5%3445%6%45%
1631
11th to 20thDay
16%6%35%6%35%45%7%42%
1638
21st to endDay
15%7%35%433446%48%
1782
February1st to 10thDay
13%9%35%5%35%5%6%8%38%
1620
11th to 20thDay
20%6%24423445%45%
1695
21st to endDay
16%8%35%5%36%5%6%6%37%
1480
March1st to 10thDay
14%6%24433346%52%
1929
11th to 20thDay
17%6%25%5%35%446%43%
1980
21st to endDay
16%7%34435%45%7%42%
2227
April1st to 10thDay
13%5%2442445%7%51%
2160
11th to 20thDay
9%5%245%35%6%6%7%48%
2134
21st to endDay
13%6%35%5%4445%6%45%
2160
May1st to 10thDay
14%5%25%5%35%45%9%42%
2171
11th to 20thDay
15%7%35%6%35%5%6%7%39%
2359
21st to endDay
13%6%25%5%35%6%6%8%42%
2725
June1st to 10thDay
11%4245%46%6%7%10%42%
2520
11th to 20thDay
10%5%25%5%45%5%7%12%40%
2520
21st to endDay
7%5%35%6%46%6%7%12%39%
2520
July1st to 10thDay
8%426%6%45%7%8%12%38%
2520
11th to 20thDay
6%5%25%6%36%6%9%11%40%
2364
21st to endDay
6%435%7%5%7%7%8%12%35%
2547
August1st to 10thDay
10%6%37%7%45%7%9%9%34%
2327
11th to 20thDay
12%6%37%8%47%5%7%8%35%
2126
21st to endDay
10%6%36%6%36%6%8%11%36%
2376
September1st to 10thDay
13%5%25%6%345%7%11%38%
2160
11th to 20thDay
13%6%27%5%35%5%5%7%43%
2160
21st to endDay
20%7%35%6%4445%7%37%
1918
October1st to 10thDay
17%6%25%5%2445%6%45%
1800
11th to 20thDay
15%6%2442335%5%50%
1800
21st to endDay
12%5%25%5%34446%50%
1980
November1st to 10thDay
14%5%24324446%51%
1790
11th to 20thDay
14%6%34323347%52%
1710
21st to endDay
15%424424436%52%
1633
December1st to 10thDay
16%6%25%5%3346%8%42%
1520
11th to 20thDay
14%6%24423345%53%
1910
21st to endDay
16%7%25%42445%7%44%
2772
January1st to 10thNight
14%6%45%424446%48%
2531
11th to 20thNight
16%6%36%5%45%5%5%7%39%
2378
21st to endNight
16%6%25%42445%6%47%
2574
February1st to 10thNight
17%7%345%3445%8%42%
2340
11th to 20thNight
20%7%25%5%24446%41%
2148
21st to endNight
17%8%24433336%47%
1776
March1st to 10thNight
14%5%245%3445%5%51%
2029
11th to 20thNight
17%6%24435%5%5%7%41%
1980
21st to endNight
16%5%36%5%35%45%7%41%
2127
April1st to 10thNight
13%7%245%35%46%7%44%
1800
11th to 20thNight
12%5%3442435%7%50%
1775
21st to endNight
14%5%346%3445%7%46%
1800
May1st to 10thNight
13%5%36%5%45%5%6%9%39%
1800
11th to 20thNight
14%5%245%35%5%6%9%41%
1534
21st to endNight
13%6%245%35%46%9%43%
1550
June1st to 10thNight
12%425%435%5%8%11%42%
1440
11th to 20thNight
9%6%26%5%35%6%7%11%40%
1440
21st to endNight
7%425%7%46%6%8%10%41%
1440
July1st to 10thNight
7%426%6%37%7%5%12%41%
1440
11th to 20thNight
7%4245%36%7%8%10%45%
1591
21st to endNight
7%5%36%6%45%8%8%11%38%
1771
August1st to 10thNight
8%427%6%46%7%7%11%37%
1611
11th to 20thNight
9%7%36%6%5%5%6%6%10%38%
1754
21st to endNight
9%6%26%6%35%6%7%11%38%
1980
September1st to 10thNight
12%5%26%5%335%6%10%44%
1800
11th to 20thNight
11%6%26%6%35%5%5%6%45%
1800
21st to endNight
20%7%36%6%35%447%37%
2038
October1st to 10thNight
16%5%25%5%3435%6%48%
2160
11th to 20thNight
16%5%24423445%50%
2160
21st to endNight
14%5%2442345%6%50%
2376
November1st to 10thNight
15%7%25%42335%5%51%
2287
11th to 20thNight
15%5%35%323447%49%
2470
21st to endNight
13%5%24435%45%6%50%
2545
December1st to 10thNight
17%6%37%5%3445%6%41%
2660
11th to 20thNight
17%6%24424447%47%
3285
21st to endNight
14%7%35%5%345%5%6%45%
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
24%39%6%19%11%1
1632
11th to 20thDay
26%41%6%13%12%2
1638
21st to endDay
27%37%5%15%14%2
1782
February1st to 10thDay
28%36%7%16%10%3
1620
11th to 20thDay
27%36%415%15%3
1704
21st to endDay
31%35%7%12%12%3
1480
March1st to 10thDay
22%36%6%19%14%4
1929
11th to 20thDay
28%37%7%14%11%4
1980
21st to endDay
31%37%7%13%11%1
2227
April1st to 10thDay
22%36%7%15%14%5%
2160
11th to 20thDay
22%37%8%15%15%4
2134
21st to endDay
26%37%6%15%12%3
2160
May1st to 10thDay
27%38%9%14%10%2
2171
11th to 20thDay
31%39%7%14%7%2
2363
21st to endDay
25%39%9%17%10%
2725
June1st to 10thDay
23%39%10%17%10%1
2520
11th to 20thDay
26%38%10%15%9%1
2520
21st to endDay
25%39%10%15%8%2
2520
July1st to 10thDay
24%40%10%15%9%2
2450
11th to 20thDay
23%42%12%14%7%2
2293
21st to endDay
25%42%14%13%7%
2405
August1st to 10thDay
27%40%10%17%6%
2314
11th to 20thDay
31%37%8%14%9%
2126
21st to endDay
28%41%9%11%8%2
2376
September1st to 10thDay
25%38%9%11%14%4
2160
11th to 20thDay
27%37%6%15%14%2
2160
21st to endDay
31%38%5%10%14%2
1918
October1st to 10thDay
26%36%415%17%3
1800
11th to 20thDay
26%37%415%14%3
1800
21st to endDay
26%37%414%16%4
1980
November1st to 10thDay
19%41%5%17%16%2
1790
11th to 20thDay
21%39%8%16%14%3
1710
21st to endDay
23%39%5%15%14%3
1633
December1st to 10thDay
22%40%7%15%13%1
1520
11th to 20thDay
25%32%5%20%13%6%
1906
21st to endDay
29%24%9%23%13%1
2772
January1st to 10thNight
24%39%7%16%12%2
2531
11th to 20thNight
27%42%7%12%10%2
2378
21st to endNight
26%37%6%15%13%3
2574
February1st to 10thNight
29%35%5%15%12%3
2340
11th to 20thNight
29%36%414%13%4
2150
21st to endNight
28%36%5%13%14%4
1776
March1st to 10thNight
22%36%7%17%16%3
2029
11th to 20thNight
29%36%7%14%10%3
1980
21st to endNight
29%38%6%14%11%3
2127
April1st to 10thNight
26%37%7%12%15%4
1800
11th to 20thNight
23%35%6%15%16%5%
1775
21st to endNight
25%37%7%17%12%3
1800
May1st to 10thNight
28%38%9%15%9%2
1800
11th to 20thNight
29%40%8%13%9%2
1535
21st to endNight
25%39%10%17%9%1
1551
June1st to 10thNight
23%39%11%17%10%
1440
11th to 20thNight
28%38%11%14%9%1
1440
21st to endNight
26%39%10%15%8%2
1440
July1st to 10thNight
24%41%10%15%8%2
1400
11th to 20thNight
20%41%13%17%7%2
1539
21st to endNight
24%43%11%16%6%
1672
August1st to 10thNight
23%41%15%15%5%
1600
11th to 20thNight
29%38%10%13%9%
1754
21st to endNight
28%41%12%12%6%1
1980
September1st to 10thNight
23%38%8%14%13%4
1800
11th to 20thNight
24%37%7%14%15%2
1800
21st to endNight
30%37%6%9%15%2
2038
October1st to 10thNight
26%36%414%18%3
2160
11th to 20thNight
27%36%6%15%14%3
2160
21st to endNight
24%37%5%14%15%4
2376
November1st to 10thNight
19%40%6%15%17%3
2287
11th to 20thNight
23%39%7%12%14%4
2470
21st to endNight
23%40%5%15%14%3
2545
December1st to 10thNight
24%40%6%14%14%2
2660
11th to 20thNight
28%32%7%13%16%4
3288
21st to endNight
29%25%10%19%15%1
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
25%21%37%12%6%
234
11th to 20thDay
24%26%35%14%1
246
21st to endDay
24%22%37%14%3
264
February1st to 10thDay
22%23%41%10%4
240
11th to 20thDay
28%24%31%14%3
363
21st to endDay
27%20%34%17%3
346
March1st to 10thDay
20%19%38%17%41
420
11th to 20thDay
25%19%31%20%5%1
420
21st to endDay
23%17%36%18%5%2
462
April1st to 10thDay
23%15%37%17%7%1
420
11th to 20thDay
14%16%36%18%11%4
412
21st to endDay
19%13%36%23%8%2
420
May1st to 10thDay
17%16%36%21%8%2
423
11th to 20thDay
20%7%31%26%14%2
447
21st to endDay
19%5%22%26%22%6%
485
June1st to 10thDay
13%5%20%32%25%4
450
11th to 20thDay
11%6%21%33%21%7%
450
21st to endDay
10%6%19%34%24%7%
450
July1st to 10thDay
10%313%34%31%9%
445
11th to 20thDay
7%112%38%30%12%
444
21st to endDay
8%217%38%26%9%
488
August1st to 10thDay
13%118%32%27%9%
446
11th to 20thDay
13%311%29%31%12%
439
21st to endDay
11%314%31%26%15%
495
September1st to 10thDay
14%318%28%21%16%
450
11th to 20thDay
14%417%32%19%14%
450
21st to endDay
26%7%21%25%14%7%
450
October1st to 10thDay
21%6%18%24%23%8%
450
11th to 20thDay
16%10%28%26%18%2
450
21st to endDay
16%10%32%26%12%4
495
November1st to 10thDay
18%9%31%22%15%4
423
11th to 20thDay
18%16%31%24%11%1
370
21st to endDay
20%15%25%25%13%2
293
December1st to 10thDay
20%21%37%14%6%1
180
11th to 20thDay
21%14%36%22%7%
180
21st to endDay
24%17%30%18%10%2
198
January1st to 10thNight
18%16%38%25%4
760
11th to 20thNight
21%12%35%26%5%
732
21st to endNight
19%13%40%27%2
792
February1st to 10thNight
21%12%41%22%4
720
11th to 20thNight
24%16%40%19%2
703
21st to endNight
20%17%38%22%3
592
March1st to 10thNight
17%14%37%26%6%
720
11th to 20thNight
22%14%35%23%6%
720
21st to endNight
19%14%36%24%6%
792
April1st to 10thNight
18%14%40%24%4
720
11th to 20thNight
15%11%38%26%10%1
711
21st to endNight
18%9%35%32%6%1
720
May1st to 10thNight
17%9%34%32%7%
720
11th to 20thNight
16%5%29%40%9%1
473
21st to endNight
15%315%46%20%2
389
June1st to 10thNight
12%419%44%19%2
360
11th to 20thNight
9%318%45%23%2
360
21st to endNight
7%418%46%24%1
360
July1st to 10thNight
10%115%46%25%3
350
11th to 20thNight
7%18%45%33%5%
495
21st to endNight
8%314%45%27%3
591
August1st to 10thNight
10%211%43%30%5%
537
11th to 20thNight
11%310%43%28%5%
690
21st to endNight
11%312%35%32%6%
792
September1st to 10thNight
14%212%39%28%6%
720
11th to 20thNight
15%313%35%28%4
720
21st to endNight
24%417%33%19%2
720
October1st to 10thNight
18%418%31%24%5%
720
11th to 20thNight
19%7%24%31%16%2
720
21st to endNight
16%6%29%31%16%2
792
November1st to 10thNight
19%6%27%29%17%2
740
11th to 20thNight
19%10%29%31%10%1
760
21st to endNight
15%9%31%32%13%1
760
December1st to 10thNight
21%11%34%27%8%1
760
11th to 20thNight
18%9%36%30%7%
760
21st to endNight
18%12%33%31%6%
836
Page generated at 2024-01-10 10:16:12. Version ac07

Copyright 2024 Attilla Danko


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