Roxborough Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Roxborough Park clear sky chart from 2005-11-06 to 2024-01-12.

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
54%
24537
29%
74419
19%
24487
64%
24487
42%
39549

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
45%
948
34%
2647
17%
946
61%
946
50%
1360
January11th to 20thNight
42%
866
34%
2495
18%
866
57%
866
48%
1288
January21st to endNight
44%
792
33%
2574
20%
792
62%
792
39%
1365
February1st to 10thNight
35%
720
29%
2340
14%
720
54%
720
40%
1211
February11th to 20thNight
36%
702
28%
2112
13%
700
52%
700
38%
1177
February21st to endNight
39%
592
37%
1776
16%
592
60%
592
43%
938
March1st to 10thNight
41%
720
29%
2160
13%
720
55%
720
43%
1145
March11th to 20thNight
49%
720
29%
2002
16%
720
57%
720
44%
1118
March21st to endNight
43%
658
30%
2044
15%
658
59%
658
37%
1126
April1st to 10thNight
40%
540
26%
1800
15%
540
54%
540
35%
943
April11th to 20thNight
41%
533
24%
1777
16%
533
54%
533
31%
1000
April21st to endNight
43%
540
23%
1800
17%
540
55%
540
30%
1038
May1st to 10thNight
49%
540
20%
1696
15%
540
56%
540
28%
1048
May11th to 20thNight
59%
531
17%
1435
15%
531
61%
531
33%
893
May21st to endNight
56%
583
20%
1552
12%
582
62%
582
39%
913
June1st to 10thNight
73%
540
24%
1440
19%
540
75%
540
53%
753
June11th to 20thNight
67%
540
26%
1440
19%
540
71%
540
53%
752
June21st to endNight
76%
540
26%
1440
22%
540
78%
540
50%
777
July1st to 10thNight
72%
525
20%
1400
18%
525
73%
525
38%
835
July11th to 20thNight
80%
522
29%
1392
25%
522
80%
522
51%
739
July21st to endNight
78%
591
22%
1540
21%
558
79%
558
39%
887
August1st to 10thNight
75%
537
16%
1606
16%
534
76%
534
35%
907
August11th to 20thNight
76%
534
27%
1778
30%
534
79%
534
41%
911
August21st to endNight
73%
594
28%
1980
30%
594
76%
594
41%
986
September1st to 10thNight
74%
540
30%
1800
31%
540
77%
540
42%
909
September11th to 20thNight
73%
540
37%
1820
35%
540
80%
540
48%
863
September21st to endNight
67%
540
33%
1980
31%
540
74%
540
42%
923
October1st to 10thNight
59%
699
29%
2139
19%
699
67%
699
42%
1132
October11th to 20thNight
60%
720
36%
2160
20%
720
71%
720
58%
1015
October21st to endNight
55%
832
35%
2416
20%
832
64%
832
46%
1277
November1st to 10thNight
57%
925
35%
2405
18%
925
66%
925
57%
1234
November11th to 20thNight
49%
950
38%
2470
18%
950
60%
950
53%
1314
November21st to endNight
52%
950
32%
2550
17%
950
62%
950
48%
1386
December1st to 10thNight
47%
950
31%
2660
16%
950
59%
950
49%
1388
December11th to 20thNight
43%
949
30%
3097
15%
948
56%
948
42%
1572
December21st to endNight
38%
1034
20%
4696
12%
1026
54%
1026
27%
2426

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
5%5%244345%6%9%53%
74766
Night
45%2442445%7%59%
74957
TransparencyDay
27%5%10%24%23%10%
74474
Night
25%5%10%25%26%9%
74771
SeeingDay
7%9%28%32%19%5%
14400
Night
6%430%43%15%2
24554

By Month

Percentage Cloud Cover SW (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
15%24223349%64%
1518
11th to 20thDay
37%44423347%60%
1502
21st to endDay
16%3443345%7%59%
1782
February1st to 10thDay
17%36%43445%7%56%
1620
11th to 20thDay
15%24435%46%9%58%
1733
21st to endDay
16%25%42445%7%58%
1480
March1st to 10thDay
35%25%43345%8%58%
1800
11th to 20thDay
5%8%3442445%8%53%
1954
21st to endDay
5%8%245%35%5%6%10%48%
2311
April1st to 10thDay
5%7%2433446%9%53%
2160
11th to 20thDay
8%7%36%5%346%6%7%46%
2131
21st to endDay
9%7%25%5%445%7%9%45%
2160
May1st to 10thDay
9%7%36%5%35%6%7%8%40%
2263
11th to 20thDay
12%7%35%5%35%7%7%10%38%
2458
21st to endDay
8%425%5%36%6%8%8%44%
2724
June1st to 10thDay
6%313446%5%8%11%49%
2520
11th to 20thDay
6%313436%7%6%9%53%
2520
21st to endDay
43245%36%7%8%10%48%
2520
July1st to 10thDay
7%3245%46%7%8%10%43%
2520
11th to 20thDay
32145%46%7%8%11%49%
2520
21st to endDay
5%325%6%46%7%9%11%42%
2684
August1st to 10thDay
5%335%6%47%8%9%11%39%
2323
11th to 20thDay
43245%45%6%7%9%51%
2123
21st to endDay
4315%6%35%6%8%9%50%
2376
September1st to 10thDay
5%314425%5%5%7%58%
2160
11th to 20thDay
6%3133245%6%6%59%
2139
21st to endDay
5%323333447%64%
1980
October1st to 10thDay
6%5%14333447%61%
1818
11th to 20thDay
4223322347%68%
1800
21st to endDay
6%7%23322346%63%
1919
November1st to 10thDay
25%13213349%67%
1673
11th to 20thDay
243432335%7%64%
1710
21st to endDay
36%34323348%61%
1625
December1st to 10thDay
15%3342336%9%59%
1520
11th to 20thDay
242442345%10%60%
1926
21st to endDay
26%26%5%35%45%7%53%
2794
January1st to 10thNight
15%25%5%23346%64%
2647
11th to 20thNight
25%34323346%65%
2495
21st to endNight
16%36%5%34446%58%
2574
February1st to 10thNight
17%35%433348%60%
2340
11th to 20thNight
27%45%5%2445%7%56%
2112
21st to endNight
17%36%423346%61%
1776
March1st to 10thNight
35%344345%6%7%58%
2160
11th to 20thNight
6%6%24323447%59%
2002
21st to endNight
5%8%34433447%57%
2044
April1st to 10thNight
5%7%23424347%59%
1800
11th to 20thNight
9%9%25%323446%53%
1777
21st to endNight
11%8%25%334436%51%
1800
May1st to 10thNight
10%6%245%25%5%5%8%46%
1696
11th to 20thNight
14%5%243235%6%9%46%
1434
21st to endNight
8%5%2433436%8%54%
1552
June1st to 10thNight
5%21232447%11%60%
1440
11th to 20thNight
6%2132235%7%8%62%
1440
21st to endNight
43123345%6%10%59%
1440
July1st to 10thNight
5%424435%5%8%10%51%
1440
11th to 20thNight
12134345%7%12%59%
1440
21st to endNight
6%313436%7%8%11%47%
1631
August1st to 10thNight
3325%5%37%7%7%8%51%
1615
11th to 20thNight
442443446%10%56%
1778
21st to endNight
43244245%6%9%56%
1980
September1st to 10thNight
7%313425%5%6%7%58%
1800
11th to 20thNight
7%31322335%6%64%
1820
21st to endNight
6%413323445%64%
1980
October1st to 10thNight
8%5%2331345%6%60%
2139
11th to 20thNight
3312323245%72%
2160
21st to endNight
5%8%23223335%63%
2416
November1st to 10thNight
2324322346%70%
2405
11th to 20thNight
25%24413336%67%
2470
21st to endNight
27%24323436%63%
2550
December1st to 10thNight
15%26%423348%62%
2660
11th to 20thNight
25%34424449%59%
3271
21st to endNight
37%36%5%3445%7%53%
4873

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
19%210%33%28%8%
1519
11th to 20thDay
26%28%31%26%8%
1502
21st to endDay
25%49%31%24%8%
1782
February1st to 10thDay
29%311%28%20%9%
1620
11th to 20thDay
23%5%6%28%29%8%
1743
21st to endDay
26%47%23%27%12%
1480
March1st to 10thDay
25%49%26%27%10%
1800
11th to 20thDay
30%49%25%25%7%
1954
21st to endDay
31%6%10%25%21%7%
2311
April1st to 10thDay
29%410%26%20%11%
2160
11th to 20thDay
35%5%8%22%20%9%
2134
21st to endDay
35%412%23%22%4
2160
May1st to 10thDay
39%6%11%23%16%4
2263
11th to 20thDay
39%8%14%24%10%5%
2462
21st to endDay
32%7%14%24%15%8%
2724
June1st to 10thDay
26%7%15%24%18%10%
2520
11th to 20thDay
26%7%10%19%21%17%
2520
21st to endDay
28%6%11%19%25%12%
2520
July1st to 10thDay
31%7%12%18%20%12%
2451
11th to 20thDay
26%7%11%25%21%9%
2445
21st to endDay
33%8%16%23%13%7%
2535
August1st to 10thDay
34%8%16%22%13%7%
2308
11th to 20thDay
26%5%10%23%24%12%
2123
21st to endDay
26%5%11%22%26%10%
2376
September1st to 10thDay
25%38%22%23%19%
2160
11th to 20thDay
22%5%8%19%28%18%
2139
21st to endDay
21%36%21%36%14%
1980
October1st to 10thDay
24%49%20%30%13%
1818
11th to 20thDay
17%47%22%34%16%
1800
21st to endDay
24%35%28%25%15%
1919
November1st to 10thDay
17%37%25%29%18%
1673
11th to 20thDay
21%35%28%33%10%
1710
21st to endDay
24%36%22%30%15%
1625
December1st to 10thDay
23%410%29%24%9%
1520
11th to 20thDay
22%49%26%32%7%
1924
21st to endDay
29%6%7%23%27%9%
2794
January1st to 10thNight
22%38%30%30%7%
2647
11th to 20thNight
22%48%28%29%9%
2495
21st to endNight
26%5%6%28%26%8%
2574
February1st to 10thNight
26%49%29%25%7%
2340
11th to 20thNight
28%47%28%24%8%
2112
21st to endNight
26%3428%27%12%
1776
March1st to 10thNight
24%5%7%25%31%8%
2160
11th to 20thNight
26%5%8%24%31%6%
2002
21st to endNight
29%49%27%26%5%
2044
April1st to 10thNight
28%5%11%25%22%10%
1800
11th to 20thNight
33%49%25%21%8%
1777
21st to endNight
36%410%26%20%5%
1800
May1st to 10thNight
36%8%11%24%16%5%
1696
11th to 20thNight
35%7%20%22%12%4
1435
21st to endNight
28%7%16%27%14%7%
1552
June1st to 10thNight
19%5%21%30%16%9%
1440
11th to 20thNight
19%5%14%22%23%17%
1440
21st to endNight
20%7%11%25%27%10%
1440
July1st to 10thNight
27%9%15%21%20%7%
1400
11th to 20thNight
18%7%12%30%23%9%
1392
21st to endNight
27%8%20%27%15%2
1540
August1st to 10thNight
28%9%20%25%13%6%
1606
11th to 20thNight
25%6%10%27%23%9%
1778
21st to endNight
24%5%13%27%24%7%
1980
September1st to 10thNight
25%5%10%21%25%15%
1800
11th to 20thNight
20%410%23%27%16%
1820
21st to endNight
22%5%7%23%33%11%
1980
October1st to 10thNight
25%5%10%20%27%13%
2139
11th to 20thNight
16%410%22%31%17%
2160
21st to endNight
25%36%25%28%13%
2416
November1st to 10thNight
17%47%26%30%17%
2405
11th to 20thNight
21%35%28%33%10%
2470
21st to endNight
25%36%22%32%12%
2550
December1st to 10thNight
22%411%27%27%9%
2660
11th to 20thNight
23%410%25%33%6%
3272
21st to endNight
31%5%8%24%26%6%
4873

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
38%31%40%14%3
270
11th to 20thDay
6%9%35%40%9%
243
21st to endDay
49%39%39%7%
264
February1st to 10thDay
213%54%26%41
240
11th to 20thDay
313%45%31%7%1
240
21st to endDay
216%39%35%7%1
198
March1st to 10thDay
411%40%33%11%2
240
11th to 20thDay
11%13%35%30%10%1
394
21st to endDay
14%23%31%24%8%
462
April1st to 10thDay
9%20%34%27%8%1
420
11th to 20thDay
14%23%31%23%7%1
412
21st to endDay
15%17%30%26%10%1
420
May1st to 10thDay
14%9%33%32%11%2
526
11th to 20thDay
15%8%26%29%18%4
625
21st to endDay
10%8%26%31%19%6%
679
June1st to 10thDay
7%6%22%31%25%9%
630
11th to 20thDay
7%6%29%32%22%5%
630
21st to endDay
6%5%24%34%26%5%
630
July1st to 10thDay
7%315%30%35%10%
621
11th to 20thDay
3216%31%37%11%
618
21st to endDay
7%312%29%37%12%
626
August1st to 10thDay
7%420%33%26%11%
447
11th to 20thDay
5%321%36%26%9%
437
21st to endDay
6%422%34%27%7%
495
September1st to 10thDay
7%424%34%24%6%
450
11th to 20thDay
6%5%23%38%20%7%
429
21st to endDay
5%6%24%30%24%10%
270
October1st to 10thDay
7%8%23%27%22%13%
270
11th to 20thDay
27%31%39%17%4
270
21st to endDay
8%10%28%35%16%2
297
November1st to 10thDay
5%10%29%37%14%5%
270
11th to 20thDay
5%8%29%40%16%3
270
21st to endDay
6%8%35%36%13%3
270
December1st to 10thDay
310%37%36%13%1
270
11th to 20thDay
48%37%40%10%
270
21st to endDay
311%42%35%7%2
297
January1st to 10thNight
35%39%41%10%2
950
11th to 20thNight
4444%38%8%2
866
21st to endNight
3440%46%7%1
792
February1st to 10thNight
4451%35%6%
720
11th to 20thNight
46%46%38%7%
704
21st to endNight
5%5%45%42%4
592
March1st to 10thNight
35%44%40%8%
720
11th to 20thNight
8%433%46%9%
720
21st to endNight
8%7%37%42%6%
658
April1st to 10thNight
8%7%41%39%5%
540
11th to 20thNight
14%9%32%37%8%1
533
21st to endNight
13%7%33%37%9%1
540
May1st to 10thNight
13%5%26%43%12%1
540
11th to 20thNight
17%314%47%17%2
531
21st to endNight
9%5%24%40%20%2
584
June1st to 10thNight
5%216%49%25%3
540
11th to 20thNight
7%222%51%17%1
540
21st to endNight
5%113%52%27%1
540
July1st to 10thNight
6%111%41%38%3
525
11th to 20thNight
229%43%41%4
522
21st to endNight
7%16%42%42%3
591
August1st to 10thNight
419%45%38%3
537
11th to 20thNight
6%310%50%29%2
534
21st to endNight
5%212%45%33%3
594
September1st to 10thNight
7%211%47%29%5%
540
11th to 20thNight
8%113%49%25%4
540
21st to endNight
7%317%49%21%2
540
October1st to 10thNight
9%424%43%17%3
699
11th to 20thNight
4230%48%14%3
720
21st to endNight
9%426%43%15%2
832
November1st to 10thNight
3430%48%12%2
925
11th to 20thNight
46%36%45%8%1
950
21st to endNight
5%5%32%45%12%
950
December1st to 10thNight
3438%45%9%1
950
11th to 20thNight
45%40%39%11%1
950
21st to endNight
6%5%43%37%8%1
1045
Page generated at 2024-01-08 20:31:29. Version ac07

Copyright 2024 Attilla Danko


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