Sun City West
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sun City West clear sky chart from 2005-11-05 to

2017-09-12
.

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
78%
15672
38%
46861
34%
15633
82%
15633
58%
21517

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
74%
718
34%
2327
34%
716
79%
716
49%
1098
January16th to endNight
67%
768
38%
2496
36%
768
76%
768
45%
1236
February1st to 15thNight
73%
699
39%
2158
36%
698
82%
698
56%
984
February16th to endNight
69%
632
36%
1895
37%
632
74%
632
47%
969
March1st to 15thNight
69%
720
42%
1989
34%
720
77%
720
62%
944
March16th to endNight
75%
768
41%
2112
32%
768
83%
768
66%
966
April1st to 15thNight
70%
719
34%
1978
22%
719
77%
719
60%
954
April16th to endNight
69%
547
47%
1669
36%
547
79%
547
74%
646
May1st to 15thNight
74%
539
40%
1619
31%
539
80%
539
68%
671
May16th to endNight
78%
561
41%
1684
32%
561
82%
561
74%
672
June1st to 15thNight
84%
540
36%
1620
30%
540
85%
540
76%
642
June16th to endNight
88%
540
36%
1620
31%
540
90%
540
76%
638
July1st to 15thNight
85%
510
28%
1530
23%
510
86%
510
56%
735
July16th to endNight
85%
564
29%
1593
25%
531
86%
531
45%
846
August1st to 15thNight
86%
539
33%
1611
28%
536
86%
536
50%
803
August16th to endNight
85%
674
35%
1880
31%
674
85%
674
51%
984
September1st to 15thNight
81%
706
34%
1942
30%
706
83%
706
56%
978
September16th to endNight
85%
656
43%
1815
35%
656
88%
656
70%
802
October1st to 15thNight
80%
660
43%
1875
36%
660
85%
660
68%
828
October16th to endNight
85%
704
45%
2112
40%
704
89%
704
70%
870
November1st to 15thNight
86%
700
43%
2160
42%
700
89%
700
68%
892
November16th to endNight
78%
720
41%
2340
41%
720
83%
720
57%
1017
December1st to 15thNight
74%
720
38%
2340
38%
720
79%
720
50%
1089
December16th to endNight
70%
768
37%
2496
38%
768
75%
768
42%
1253

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
2112212336%71%
47795
Night
3212213345%70%
47059
TransparencyDay
15%2312%25%41%
47490
Night
16%1311%23%43%
46865
SeeingDay
4316%32%31%11%
5475
Night
4110%42%37%3
15682

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
5%213312325%68%
1611
16th to endDay
6%214212236%66%
1728
February1st to 15thDay
3313313336%67%
1700
16th to endDay
6%313312346%63%
1579
March1st to 15thDay
3211213336%69%
1971
16th to endDay
2112213235%72%
2112
April1st to 15thDay
212212447%70%
1970
16th to endDay
111111225%81%
2286
May1st to 15thDay
1111225%80%
2331
16th to endDay
1111112383%
2429
June1st to 15thDay
111112483%
2340
16th to endDay
111112484%
2340
July1st to 15thDay
111332345%7%64%
2340
16th to endDay
3324425%6%7%10%47%
2467
August1st to 15thDay
321332346%9%59%
2340
16th to endDay
311322346%7%63%
2320
September1st to 15thDay
5%212313347%64%
1937
16th to endDay
11111122480%
1815
October1st to 15thDay
11111223477%
1755
16th to endDay
1111123479%
1760
November1st to 15thDay
12212235%77%
1696
16th to endDay
4112212135%73%
1620
December1st to 15thDay
421241345%6%63%
1620
16th to endDay
5%324312446%61%
1728
January1st to 15thNight
5%21232334466%
2327
16th to endNight
7%313213235%64%
2496
February1st to 15thNight
3312212345%69%
2149
16th to endNight
6%213323435%62%
1895
March1st to 15thNight
3212212235%70%
1989
16th to endNight
311112245%73%
2112
April1st to 15thNight
2112213336%69%
1978
16th to endNight
111122384%
1669
May1st to 15thNight
111212335%77%
1619
16th to endNight
11111111385%
1684
June1st to 15thNight
11222482%
1620
16th to endNight
112112384%
1620
July1st to 15thNight
11124135%6%9%61%
1620
16th to endNight
2213435%5%7%12%50%
1701
August1st to 15thNight
2113325%47%10%58%
1620
16th to endNight
11125%35%5%6%8%59%
1880
September1st to 15thNight
22123235%6%7%60%
1942
16th to endNight
11121223478%
1815
October1st to 15thNight
2112112235%76%
1875
16th to endNight
11211223478%
2112
November1st to 15thNight
1111112235%75%
2160
16th to endNight
31321222473%
2340
December1st to 15thNight
5%222213345%65%
2340
16th to endNight
6%313423336%60%
2496

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
19%2415%29%29%
1612
16th to endDay
21%1216%27%30%
1728
February1st to 15thDay
18%1417%27%29%
1700
16th to endDay
21%2216%30%25%
1579
March1st to 15thDay
17%119%31%38%
1971
16th to endDay
16%129%32%37%
2112
April1st to 15thDay
13%19%34%39%
1970
16th to endDay
9%117%24%56%
2286
May1st to 15thDay
8%117%24%56%
2331
16th to endDay
9%16%21%61%
2432
June1st to 15thDay
8%315%71%
2340
16th to endDay
7%1310%76%
2340
July1st to 15thDay
17%37%15%18%37%
2201
16th to endDay
26%5%10%23%19%13%
2312
August1st to 15thDay
20%36%17%20%31%
2325
16th to endDay
18%36%16%29%26%
2320
September1st to 15thDay
20%2412%24%34%
1937
16th to endDay
9%25%26%56%
1815
October1st to 15thDay
11%1210%26%46%
1755
16th to endDay
9%137%29%47%
1760
November1st to 15thDay
11%1113%32%41%
1696
16th to endDay
15%1111%29%41%
1620
December1st to 15thDay
22%1418%27%25%
1620
16th to endDay
24%1423%29%16%
1728
January1st to 15thNight
21%1411%25%35%
2327
16th to endNight
25%1212%26%32%
2496
February1st to 15thNight
18%1415%24%36%
2160
16th to endNight
24%2211%28%31%
1895
March1st to 15thNight
15%119%24%47%
1989
16th to endNight
13%128%30%43%
2112
April1st to 15thNight
16%117%28%44%
1978
16th to endNight
7%116%21%61%
1669
May1st to 15thNight
10%115%24%55%
1620
16th to endNight
8%5%18%65%
1685
June1st to 15thNight
7%1314%72%
1620
16th to endNight
8%1127%79%
1620
July1st to 15thNight
17%38%17%15%37%
1530
16th to endNight
23%5%10%21%20%17%
1593
August1st to 15thNight
20%46%19%18%30%
1611
16th to endNight
22%37%13%23%30%
1880
September1st to 15thNight
18%37%17%20%32%
1942
16th to endNight
11%115%20%60%
1815
October1st to 15thNight
12%1110%23%50%
1875
16th to endNight
10%129%17%58%
2112
November1st to 15thNight
11%119%28%47%
2160
16th to endNight
17%128%23%46%
2340
December1st to 15thNight
20%1313%27%32%
2340
16th to endNight
26%2415%29%21%
2496

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
24%10%43%18%3
90
16th to endDay
6%214%34%29%13%
96
February1st to 15thDay
3316%33%35%7%
215
16th to endDay
9%6%26%31%21%4
238
March1st to 15thDay
5%6%22%27%24%12%
270
16th to endDay
37%27%30%22%9%
288
April1st to 15thDay
5%10%23%29%21%8%
269
16th to endDay
311%35%28%14%6%
270
May1st to 15thDay
29%26%35%19%7%
288
16th to endDay
2425%33%25%8%
330
June1st to 15thDay
1322%36%26%9%
315
16th to endDay
110%36%37%13%
315
July1st to 15thDay
16%39%37%14%
305
16th to endDay
4327%39%24%
327
August1st to 15thDay
2329%46%17%
315
16th to endDay
15%25%48%18%
332
September1st to 15thDay
7%8%32%41%11%
300
16th to endDay
3116%34%32%10%
255
October1st to 15thDay
3220%29%33%10%
195
16th to endDay
46%27%46%15%
96
November1st to 15thDay
112%36%35%14%
90
16th to endDay
5%20%42%24%7%
90
December1st to 15thDay
2110%27%45%13%
90
16th to endDay
11%319%36%27%2
96
January1st to 15thNight
7%111%48%27%3
720
16th to endNight
9%114%46%25%3
768
February1st to 15thNight
5%213%47%28%2
704
16th to endNight
6%214%52%22%2
632
March1st to 15thNight
6%117%41%30%2
720
16th to endNight
4213%45%30%3
768
April1st to 15thNight
3317%46%26%2
719
16th to endNight
1423%44%23%2
547
May1st to 15thNight
1317%45%28%2
540
16th to endNight
1115%44%34%1
563
June1st to 15thNight
112%55%29%
540
16th to endNight
16%46%43%2
540
July1st to 15thNight
15%34%54%3
510
16th to endNight
11225%60%7%
564
August1st to 15thNight
3225%59%9%
539
16th to endNight
2323%61%9%
674
September1st to 15thNight
316%28%53%6%
706
16th to endNight
117%38%44%5%
656
October1st to 15thNight
3110%43%39%2
660
16th to endNight
18%41%42%5%
704
November1st to 15thNight
217%46%38%4
700
16th to endNight
5%10%43%35%4
720
December1st to 15thNight
6%110%43%35%1
720
16th to endNight
8%29%49%26%2
768
Page generated at 2017-09-13 04:39:19. Version ac04

Copyright 2017 A. Danko


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