Roxborough Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Roxborough Park clear sky chart from 2005-11-05 to 2018-08-29.

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
61%
17204
29%
50610
21%
17162
68%
17162
44%
27055

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 15thNight
58%
973
32%
2716
23%
970
67%
970
51%
1387
January16th to endNight
56%
868
35%
2740
28%
868
67%
868
44%
1401
February1st to 15thNight
49%
760
26%
2432
19%
758
59%
758
39%
1307
February16th to endNight
47%
684
35%
2050
19%
684
63%
684
43%
1089
March1st to 15thNight
55%
780
30%
2291
17%
780
65%
780
46%
1206
March16th to endNight
50%
735
30%
2191
18%
735
61%
735
41%
1198
April1st to 15thNight
48%
584
25%
1948
20%
584
58%
584
35%
1038
April16th to endNight
47%
579
23%
1929
19%
579
57%
579
29%
1118
May1st to 15thNight
54%
584
20%
1757
17%
584
59%
584
28%
1113
May16th to endNight
60%
610
19%
1626
14%
609
64%
609
40%
939
June1st to 15thNight
72%
585
25%
1560
19%
585
75%
585
56%
790
June16th to endNight
76%
585
25%
1560
21%
585
79%
585
54%
804
July1st to 15thNight
73%
555
20%
1480
17%
555
74%
555
39%
875
July16th to endNight
78%
612
23%
1581
22%
579
79%
579
44%
881
August1st to 15thNight
76%
575
20%
1784
20%
572
77%
572
38%
963
August16th to endNight
74%
615
27%
2050
29%
615
76%
615
41%
1041
September1st to 15thNight
73%
540
28%
1800
29%
540
77%
540
40%
935
September16th to endNight
72%
537
35%
1934
35%
537
78%
537
45%
898
October1st to 15thNight
62%
707
30%
2147
21%
707
68%
707
44%
1117
October16th to endNight
68%
796
37%
2332
26%
796
73%
796
50%
1186
November1st to 15thNight
63%
950
34%
2470
21%
950
69%
950
54%
1302
November16th to endNight
64%
975
37%
2590
24%
975
70%
975
54%
1353
December1st to 15thNight
56%
975
27%
2730
17%
975
63%
975
47%
1461
December16th to endNight
52%
1040
30%
2912
18%
1040
62%
1040
42%
1653

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%42442446%8%52%
51654
Night
442332335%7%59%
50786
Cloud CoverDay
5%41342445%8%53%
51652
Night
4423323347%59%
50786
TransparencyDay
28%410%25%22%9%
51332
Night
24%411%27%24%8%
50610
SeeingDay
9%6%25%31%20%6%
7110
Night
7%321%47%18%2
17212

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 15thDay
15%23222238%61%
1552
16th to endDay
15%23222348%62%
1846
February1st to 15thDay
16%26%32435%7%55%
1758
16th to endDay
6%2331445%7%59%
1710
March1st to 15thDay
3415%323349%56%
1997
16th to endDay
5%6%2342445%8%50%
2385
April1st to 15thDay
6%7%2332345%8%51%
2330
16th to endDay
11%7%2443446%6%44%
2306
May1st to 15thDay
9%6%36%5%35%5%6%8%40%
2522
16th to endDay
9%424425%6%8%8%41%
2840
June1st to 15thDay
6%212436%5%7%9%51%
2730
16th to endDay
3213425%6%7%10%52%
2730
July1st to 15thDay
6%3145%45%6%8%10%43%
2730
16th to endDay
5%325%5%35%6%8%11%43%
2838
August1st to 15thDay
5%325%6%46%6%7%9%41%
2418
16th to endDay
42145%35%6%8%9%48%
2449
September1st to 15thDay
7%3133245%6%7%53%
2160
16th to endDay
5%313323446%61%
2025
October1st to 15thDay
5%413322447%61%
1812
16th to endDay
6%412211246%64%
1878
November1st to 15thDay
142331335%9%62%
1718
16th to endDay
2423212249%63%
1696
December1st to 15thDay
143431335%8%58%
1560
16th to endDay
2415%423349%57%
1664
January1st to 15thNight
1324322346%65%
2716
16th to endNight
15%24413335%63%
2740
February1st to 15thNight
17%24423347%57%
2422
16th to endNight
17%35%313345%60%
2050
March1st to 15thNight
24223235%5%7%59%
2291
16th to endNight
6%5%23223346%59%
2191
April1st to 15thNight
6%7%13223347%56%
1948
16th to endNight
12%7%24323335%51%
1929
May1st to 15thNight
13%6%244145%5%8%44%
1756
16th to endNight
7%41332446%8%53%
1625
June1st to 15thNight
421121336%9%64%
1560
16th to endNight
32222346%9%62%
1560
July1st to 15thNight
4323425%5%7%10%50%
1560
16th to endNight
4213335%5%8%11%50%
1680
August1st to 15thNight
2314326%6%7%8%52%
1793
16th to endNight
43133235%6%9%54%
2050
September1st to 15thNight
8%21332446%7%55%
1800
16th to endNight
5%33213345%65%
1934
October1st to 15thNight
7%413313345%62%
2147
16th to endNight
45%12222246%64%
2332
November1st to 15thNight
2313312346%66%
2470
16th to endNight
25%23312336%66%
2590
December1st to 15thNight
2425%313248%60%
2730
16th to endNight
26%34324347%56%
2912

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 15thDay
16%23312248%62%
1552
16th to endDay
25%23222337%63%
1846
February1st to 15thDay
16%36%323347%56%
1758
16th to endDay
16%23324447%60%
1710
March1st to 15thDay
4424423448%57%
1997
16th to endDay
6%6%2332435%8%52%
2383
April1st to 15thDay
7%6%2332345%8%52%
2330
16th to endDay
11%7%1442445%6%45%
2306
May1st to 15thDay
10%6%25%6%25%5%5%8%41%
2522
16th to endDay
10%5%14425%6%7%9%42%
2840
June1st to 15thDay
6%212435%5%7%8%51%
2730
16th to endDay
323335%6%6%10%53%
2730
July1st to 15thDay
7%2145%26%5%8%10%44%
2730
16th to endDay
6%2145%35%5%8%10%44%
2838
August1st to 15thDay
6%215%6%45%7%7%10%42%
2418
16th to endDay
5%2144346%7%9%49%
2449
September1st to 15thDay
7%31332445%7%55%
2160
16th to endDay
5%312233347%62%
2025
October1st to 15thDay
6%413313347%61%
1812
16th to endDay
6%412312245%65%
1878
November1st to 15thDay
231322235%8%63%
1718
16th to endDay
3433212348%64%
1696
December1st to 15thDay
15%23323449%59%
1560
16th to endDay
2424423348%57%
1664
January1st to 15thNight
1324322246%65%
2716
16th to endNight
16%24312335%63%
2740
February1st to 15thNight
16%35%42235%6%58%
2422
16th to endNight
18%24313345%60%
2050
March1st to 15thNight
342321345%7%60%
2291
16th to endNight
6%5%23222346%59%
2191
April1st to 15thNight
7%6%13214347%57%
1948
16th to endNight
13%7%13313435%51%
1929
May1st to 15thNight
14%5%1332345%7%45%
1756
16th to endNight
7%4233135%5%8%54%
1625
June1st to 15thNight
41121235%9%65%
1560
16th to endNight
311211345%10%63%
1560
July1st to 15thNight
5%3134245%7%10%51%
1560
16th to endNight
42123246%6%12%51%
1680
August1st to 15thNight
32144245%7%9%53%
1793
16th to endNight
5%21332346%9%55%
2050
September1st to 15thNight
9%21331446%7%56%
1800
16th to endNight
6%23213445%65%
1934
October1st to 15thNight
7%413312345%62%
2147
16th to endNight
5%6%12222236%64%
2332
November1st to 15thNight
2313312346%67%
2470
16th to endNight
2423212335%67%
2590
December1st to 15thNight
25%25%412238%60%
2730
16th to endNight
26%34323446%56%
2912

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 15thDay
22%211%33%24%5%
1553
16th to endDay
22%29%33%24%8%
1846
February1st to 15thDay
28%312%34%16%4
1759
16th to endDay
24%46%26%29%8%
1710
March1st to 15thDay
25%39%26%25%9%
1997
16th to endDay
30%5%10%26%21%6%
2385
April1st to 15thDay
30%410%27%19%8%
2330
16th to endDay
38%410%22%19%5%
2306
May1st to 15thDay
40%6%12%23%14%3
2522
16th to endDay
34%7%14%22%13%7%
2844
June1st to 15thDay
27%5%13%20%19%14%
2730
16th to endDay
24%5%10%20%26%12%
2730
July1st to 15thDay
31%6%11%20%17%11%
2581
16th to endDay
31%6%14%25%15%6%
2674
August1st to 15thDay
33%6%14%20%14%9%
2403
16th to endDay
28%412%24%23%6%
2449
September1st to 15thDay
28%39%22%20%15%
2160
16th to endDay
22%37%22%33%10%
2025
October1st to 15thDay
23%49%21%30%10%
1812
16th to endDay
21%26%27%29%12%
1878
November1st to 15thDay
19%38%27%27%13%
1718
16th to endDay
20%25%25%34%11%
1696
December1st to 15thDay
23%410%31%23%6%
1560
16th to endDay
26%412%26%22%7%
1664
January1st to 15thNight
20%210%33%26%6%
2716
16th to endNight
24%37%28%27%8%
2740
February1st to 15thNight
28%411%32%19%4
2432
16th to endNight
26%2428%26%10%
2050
March1st to 15thNight
23%47%26%30%8%
2291
16th to endNight
27%38%28%25%5%
2191
April1st to 15thNight
28%411%25%21%7%
1948
16th to endNight
35%310%26%19%5%
1929
May1st to 15thNight
37%7%12%22%14%4
1757
16th to endNight
27%6%19%26%13%6%
1626
June1st to 15thNight
17%317%28%18%14%
1560
16th to endNight
17%5%12%24%27%12%
1560
July1st to 15thNight
27%7%15%21%18%8%
1480
16th to endNight
23%7%18%29%17%3
1581
August1st to 15thNight
25%7%17%26%15%7%
1784
16th to endNight
24%413%28%21%6%
2050
September1st to 15thNight
26%412%22%21%12%
1800
16th to endNight
20%48%27%31%7%
1934
October1st to 15thNight
24%311%21%27%11%
2147
16th to endNight
21%37%25%30%11%
2332
November1st to 15thNight
19%37%27%28%14%
2470
16th to endNight
20%26%25%33%10%
2590
December1st to 15thNight
24%313%29%22%7%
2730
16th to endNight
28%412%26%24%4
2912

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 15thDay
9%5%21%38%20%4
135
16th to endDay
5%229%50%13%
144
February1st to 15thDay
5%7%43%37%6%
135
16th to endDay
3337%41%11%2
120
March1st to 15thDay
6%8%36%36%10%1
182
16th to endDay
16%18%33%24%6%
352
April1st to 15thDay
13%18%35%23%7%1
329
16th to endDay
23%16%30%19%8%1
318
May1st to 15thDay
15%7%28%27%17%3
488
16th to endDay
16%6%21%27%21%6%
597
June1st to 15thDay
6%6%22%32%24%8%
570
16th to endDay
6%326%30%25%8%
570
July1st to 15thDay
7%315%25%35%12%
550
16th to endDay
6%114%30%34%12%
553
August1st to 15thDay
10%223%32%21%9%
359
16th to endDay
7%326%32%20%8%
385
September1st to 15thDay
10%426%30%20%7%
315
16th to endDay
9%5%28%28%17%10%
180
October1st to 15thDay
7%5%23%31%20%11%
135
16th to endDay
7%321%38%22%6%
144
November1st to 15thDay
1320%40%24%9%
135
16th to endDay
8%5%27%48%9%
135
December1st to 15thDay
2438%44%9%
135
16th to endDay
2138%44%9%3
144
January1st to 15thNight
3328%51%11%2
975
16th to endNight
4327%53%9%1
868
February1st to 15thNight
6%331%50%7%
764
16th to endNight
5%434%47%5%
684
March1st to 15thNight
4330%49%10%
780
16th to endNight
9%430%46%8%
735
April1st to 15thNight
11%6%29%43%7%
584
16th to endNight
18%6%23%39%12%
579
May1st to 15thNight
18%217%42%17%1
585
16th to endNight
10%318%42%23%1
611
June1st to 15thNight
5%216%48%23%3
585
16th to endNight
5%112%49%30%1
585
July1st to 15thNight
7%17%38%40%4
555
16th to endNight
6%6%39%42%4
612
August1st to 15thNight
417%42%39%3
575
16th to endNight
6%18%42%36%3
615
September1st to 15thNight
8%19%42%31%6%
540
16th to endNight
6%113%44%29%3
537
October1st to 15thNight
10%220%45%17%4
707
16th to endNight
8%215%48%21%3
796
November1st to 15thNight
4322%51%15%2
950
16th to endNight
4223%54%13%1
975
December1st to 15thNight
4328%52%10%
975
16th to endNight
5%329%48%11%1
1040
Page generated at 2018-08-30 03:34:23. Version ac04

Copyright 2018 A. Danko


Roxborough Park Clear Sky Chart |Charts Home