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 2017-09-17.

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%
15925
28%
46871
21%
15883
68%
15883
43%
25113

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
57%
898
33%
2506
23%
895
66%
895
51%
1279
January16th to endNight
53%
801
34%
2529
26%
801
65%
801
42%
1311
February1st to 15thNight
48%
700
26%
2241
19%
698
58%
698
39%
1206
February16th to endNight
46%
632
35%
1894
19%
632
62%
632
43%
1000
March1st to 15thNight
55%
720
29%
2115
16%
720
65%
720
44%
1131
March16th to endNight
50%
678
29%
2022
17%
678
61%
678
41%
1100
April1st to 15thNight
49%
539
25%
1798
21%
539
60%
539
37%
941
April16th to endNight
47%
540
23%
1800
19%
540
56%
540
29%
1050
May1st to 15thNight
56%
539
20%
1622
16%
539
61%
539
29%
1016
May16th to endNight
59%
562
19%
1498
13%
561
63%
561
40%
870
June1st to 15thNight
72%
540
23%
1440
17%
540
75%
540
54%
741
June16th to endNight
77%
540
26%
1440
22%
540
80%
540
56%
729
July1st to 15thNight
73%
510
18%
1360
15%
510
74%
510
37%
819
July16th to endNight
78%
564
23%
1450
22%
531
80%
531
44%
802
August1st to 15thNight
74%
539
19%
1674
19%
536
76%
536
37%
917
August16th to endNight
74%
573
28%
1910
30%
573
77%
573
40%
973
September1st to 15thNight
72%
540
28%
1800
29%
540
76%
540
40%
935
September16th to endNight
75%
498
35%
1793
36%
498
80%
498
47%
816
October1st to 15thNight
60%
648
31%
1968
21%
648
66%
648
43%
1035
October16th to endNight
68%
729
35%
2137
24%
729
73%
729
50%
1087
November1st to 15thNight
64%
875
35%
2275
21%
875
70%
875
54%
1202
November16th to endNight
65%
900
36%
2391
24%
900
70%
900
53%
1257
December1st to 15thNight
56%
900
27%
2520
17%
900
63%
900
46%
1357
December16th to endNight
51%
960
29%
2688
17%
960
61%
960
41%
1539

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%
47916
Night
442332335%7%58%
47047
Cloud CoverDay
5%41342445%8%53%
47914
Night
4423323347%59%
47047
TransparencyDay
28%411%24%21%8%
47594
Night
25%411%27%23%8%
46871
SeeingDay
10%6%24%30%20%6%
5842
Night
7%321%46%18%2
15933

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
16%23223238%62%
1432
16th to endDay
15%23212347%62%
1704
February1st to 15thDay
16%26%32435%6%55%
1619
16th to endDay
16%3431435%7%58%
1580
March1st to 15thDay
4415%423449%55%
1843
16th to endDay
5%7%2342445%8%49%
2202
April1st to 15thDay
7%7%1332445%8%51%
2150
16th to endDay
11%6%25%4345%6%6%44%
2160
May1st to 15thDay
9%6%36%5%35%5%6%7%40%
2327
16th to endDay
9%5%24425%6%8%8%41%
2616
June1st to 15thDay
6%212436%5%7%9%51%
2520
16th to endDay
2213425%7%7%10%53%
2520
July1st to 15thDay
6%3145%46%6%8%10%41%
2520
16th to endDay
5%325%5%35%6%8%11%42%
2617
August1st to 15thDay
5%325%6%46%6%7%9%41%
2275
16th to endDay
5%2145%35%6%8%9%48%
2292
September1st to 15thDay
7%3133245%6%7%53%
2160
16th to endDay
4213323446%63%
1871
October1st to 15thDay
5%313322447%60%
1661
16th to endDay
6%412211246%64%
1722
November1st to 15thDay
142331335%8%62%
1583
16th to endDay
2433312248%63%
1566
December1st to 15thDay
15%3431435%8%57%
1440
16th to endDay
25%15%5%23349%55%
1536
January1st to 15thNight
1314322346%65%
2506
16th to endNight
15%2442333462%
2529
February1st to 15thNight
17%34423347%58%
2231
16th to endNight
17%34313346%60%
1894
March1st to 15thNight
34223245%5%7%58%
2115
16th to endNight
5%5%23223346%59%
2022
April1st to 15thNight
6%7%12213347%58%
1798
16th to endNight
13%7%24323335%50%
1800
May1st to 15thNight
12%6%2332445%9%45%
1621
16th to endNight
7%42332446%9%52%
1497
June1st to 15thNight
421121345%8%63%
1440
16th to endNight
21112346%9%64%
1440
July1st to 15thNight
4324425%5%7%10%48%
1440
16th to endNight
4213335%5%8%11%50%
1549
August1st to 15thNight
2314326%6%7%8%52%
1683
16th to endNight
43133235%6%9%54%
1910
September1st to 15thNight
8%21332446%7%55%
1800
16th to endNight
422213345%66%
1793
October1st to 15thNight
7%413313345%61%
1968
16th to endNight
5%5%12222246%63%
2137
November1st to 15thNight
2314313346%66%
2275
16th to endNight
25%23312335%66%
2391
December1st to 15thNight
2435%313249%58%
2520
16th to endNight
26%35%323347%55%
2688

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%23313248%62%
1432
16th to endDay
25%23212337%63%
1704
February1st to 15thDay
16%36%323347%56%
1619
16th to endDay
16%23224346%59%
1580
March1st to 15thDay
4424423448%56%
1843
16th to endDay
6%6%2332436%8%51%
2200
April1st to 15thDay
7%6%1332345%8%52%
2150
16th to endDay
11%6%1443445%6%45%
2160
May1st to 15thDay
10%6%25%6%15%5%5%7%41%
2327
16th to endDay
10%5%14425%6%7%9%42%
2616
June1st to 15thDay
6%212435%5%7%8%51%
2520
16th to endDay
322325%6%7%10%54%
2520
July1st to 15thDay
7%2145%26%6%8%10%42%
2520
16th to endDay
6%2145%35%5%8%10%44%
2617
August1st to 15thDay
6%215%6%45%7%7%9%42%
2275
16th to endDay
5%2144346%7%9%49%
2292
September1st to 15thDay
7%31332445%7%55%
2160
16th to endDay
4212233347%63%
1871
October1st to 15thDay
6%312313348%60%
1661
16th to endDay
6%412312245%65%
1722
November1st to 15thDay
241322235%8%62%
1583
16th to endDay
2433212348%63%
1566
December1st to 15thDay
25%24423448%58%
1440
16th to endDay
25%24423348%56%
1536
January1st to 15thNight
1324322246%65%
2506
16th to endNight
16%25%41333463%
2529
February1st to 15thNight
27%35%322346%58%
2231
16th to endNight
18%34313345%60%
1894
March1st to 15thNight
342322345%6%59%
2115
16th to endNight
6%5%23222346%59%
2022
April1st to 15thNight
6%6%13214347%59%
1798
16th to endNight
13%7%24313435%51%
1800
May1st to 15thNight
14%5%1322346%8%46%
1621
16th to endNight
7%5%233135%6%8%53%
1497
June1st to 15thNight
5%2122235%9%63%
1440
16th to endNight
21211345%10%64%
1440
July1st to 15thNight
5%3135%245%7%11%49%
1440
16th to endNight
4212325%6%6%12%51%
1549
August1st to 15thNight
32144245%7%8%53%
1683
16th to endNight
5%21332346%9%55%
1910
September1st to 15thNight
9%21331446%7%56%
1800
16th to endNight
5%22113445%67%
1793
October1st to 15thNight
7%413312345%61%
1968
16th to endNight
5%5%12222236%64%
2137
November1st to 15thNight
2313312345%68%
2275
16th to endNight
25%23212335%67%
2391
December1st to 15thNight
25%25%412249%59%
2520
16th to endNight
26%35%323446%56%
2688

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%34%24%5%
1433
16th to endDay
22%29%33%24%8%
1704
February1st to 15thDay
28%311%34%17%4
1620
16th to endDay
25%47%27%27%7%
1580
March1st to 15thDay
26%39%26%24%8%
1843
16th to endDay
31%5%10%25%21%6%
2202
April1st to 15thDay
30%310%26%19%8%
2150
16th to endDay
38%410%22%19%5%
2160
May1st to 15thDay
40%6%12%22%14%3
2327
16th to endDay
34%7%14%23%12%6%
2620
June1st to 15thDay
27%5%13%20%18%12%
2520
16th to endDay
23%5%10%20%27%12%
2520
July1st to 15thDay
33%6%12%20%15%10%
2371
16th to endDay
32%6%14%24%15%6%
2453
August1st to 15thDay
34%6%14%19%15%9%
2260
16th to endDay
27%5%12%24%23%7%
2292
September1st to 15thDay
28%39%22%20%15%
2160
16th to endDay
20%37%23%34%10%
1871
October1st to 15thDay
23%410%21%30%9%
1661
16th to endDay
21%36%27%29%11%
1722
November1st to 15thDay
20%39%26%26%14%
1583
16th to endDay
21%25%26%33%11%
1566
December1st to 15thDay
25%411%31%22%5%
1440
16th to endDay
27%413%26%20%7%
1536
January1st to 15thNight
20%211%32%26%6%
2506
16th to endNight
25%37%28%25%9%
2529
February1st to 15thNight
28%310%32%19%4
2241
16th to endNight
25%35%30%25%9%
1894
March1st to 15thNight
24%47%26%29%7%
2115
16th to endNight
27%38%27%26%6%
2022
April1st to 15thNight
27%412%25%21%8%
1798
16th to endNight
36%310%25%18%5%
1800
May1st to 15thNight
36%8%12%22%15%5%
1622
16th to endNight
27%6%20%26%12%6%
1498
June1st to 15thNight
18%418%28%16%13%
1440
16th to endNight
16%5%12%24%28%12%
1440
July1st to 15thNight
29%8%16%20%16%8%
1360
16th to endNight
23%7%17%30%17%3
1450
August1st to 15thNight
26%8%17%25%15%7%
1674
16th to endNight
25%5%12%27%22%6%
1910
September1st to 15thNight
26%412%22%21%12%
1800
16th to endNight
19%48%27%32%7%
1793
October1st to 15thNight
24%411%21%27%10%
1968
16th to endNight
21%37%26%30%10%
2137
November1st to 15thNight
20%37%27%27%14%
2275
16th to endNight
20%36%24%34%10%
2391
December1st to 15thNight
24%314%30%20%5%
2520
16th to endNight
29%413%26%22%4
2688

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
13%5%17%30%26%6%
90
16th to endDay
7%125%50%16%
96
February1st to 15thDay
5%5%41%38%8%
90
16th to endDay
4428%40%17%3
81
March1st to 15thDay
6%10%33%39%9%1
133
16th to endDay
17%20%31%22%6%1
288
April1st to 15thDay
15%17%33%21%9%2
269
16th to endDay
23%17%31%19%7%
270
May1st to 15thDay
16%8%27%29%15%3
417
16th to endDay
17%7%20%27%20%6%
517
June1st to 15thDay
7%6%21%32%23%8%
495
16th to endDay
5%326%29%27%8%
495
July1st to 15thDay
8%316%26%32%12%
475
16th to endDay
6%214%29%35%11%
476
August1st to 15thDay
11%225%32%20%8%
315
16th to endDay
7%326%32%21%8%
332
September1st to 15thDay
10%426%30%20%7%
315
16th to endDay
4228%30%20%13%
136
October1st to 15thDay
4220%34%24%14%
90
16th to endDay
7%320%36%25%7%
96
November1st to 15thDay
1316%31%33%14%
90
16th to endDay
10%6%30%40%12%1
90
December1st to 15thDay
45%35%47%6%
90
16th to endDay
4237%45%6%4
96
January1st to 15thNight
3329%49%12%2
900
16th to endNight
3328%52%9%1
801
February1st to 15thNight
6%332%49%8%
704
16th to endNight
6%435%46%6%
632
March1st to 15thNight
5%330%49%11%
720
16th to endNight
9%430%46%9%
678
April1st to 15thNight
11%6%29%44%7%
539
16th to endNight
18%6%23%39%12%
540
May1st to 15thNight
17%217%43%17%1
540
16th to endNight
10%319%41%22%2
563
June1st to 15thNight
5%215%49%22%3
540
16th to endNight
4111%49%31%
540
July1st to 15thNight
7%17%36%42%4
510
16th to endNight
6%5%38%44%4
564
August1st to 15thNight
5%17%43%39%3
539
16th to endNight
7%18%42%36%3
573
September1st to 15thNight
8%19%42%31%6%
540
16th to endNight
5%112%45%30%3
498
October1st to 15thNight
10%221%43%18%4
648
16th to endNight
8%215%47%21%3
729
November1st to 15thNight
3322%51%16%2
875
16th to endNight
4322%54%14%1
900
December1st to 15thNight
4328%52%10%
900
16th to endNight
6%429%48%10%1
960
Page generated at 2017-09-18 06:38:29. Version ac04

Copyright 2017 A. Danko


Roxborough Park Clear Sky Chart | Charts Home