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 2017-04-08.

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
77%
15181
38%
45416
34%
15142
82%
15142
58%
20844

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
69%
691
35%
1901
23%
691
76%
691
58%
924
April16th to endNight
70%
502
45%
1531
35%
502
79%
502
74%
598
May1st to 15thNight
74%
494
42%
1484
33%
494
81%
494
68%
612
May16th to endNight
78%
513
38%
1540
30%
513
82%
513
73%
620
June1st to 15thNight
84%
495
38%
1485
32%
495
86%
495
76%
589
June16th to endNight
88%
495
34%
1485
29%
495
89%
495
76%
586
July1st to 15thNight
84%
465
29%
1395
24%
465
85%
465
55%
674
July16th to endNight
86%
522
30%
1467
25%
489
87%
489
48%
755
August1st to 15thNight
86%
494
35%
1476
29%
491
87%
491
52%
724
August16th to endNight
85%
617
33%
1722
29%
617
85%
617
50%
906
September1st to 15thNight
81%
660
36%
1815
31%
660
84%
660
57%
908
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
2212212336%70%
45840
Night
3212213345%70%
45614
TransparencyDay
15%1312%25%40%
45535
Night
16%1311%23%43%
45420
SeeingDay
4317%33%30%9%
4856
Night
4111%42%36%3
15191

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%71%
1886
16th to endDay
11111122481%
2096
May1st to 15thDay
1111225%81%
2136
16th to endDay
21111112382%
2221
June1st to 15thDay
111212482%
2145
16th to endDay
111112484%
2145
July1st to 15thDay
211332445%8%62%
2145
16th to endDay
3324425%6%7%10%48%
2285
August1st to 15thDay
321232446%9%59%
2145
16th to endDay
311322346%7%62%
2126
September1st to 15thDay
5%212313347%64%
1815
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%
1901
16th to endNight
111122384%
1531
May1st to 15thNight
11212235%77%
1484
16th to endNight
11111111384%
1540
June1st to 15thNight
11222482%
1485
16th to endNight
112112384%
1485
July1st to 15thNight
11134135%6%10%60%
1485
16th to endNight
2213425%5%7%12%52%
1575
August1st to 15thNight
111322447%10%58%
1485
16th to endNight
1113435%5%6%8%58%
1722
September1st to 15thNight
22123235%6%7%61%
1815
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%35%39%
1886
16th to endDay
9%117%23%56%
2096
May1st to 15thDay
8%117%25%57%
2136
16th to endDay
9%6%22%60%
2224
June1st to 15thDay
9%315%71%
2145
16th to endDay
7%1410%75%
2145
July1st to 15thDay
19%37%14%18%36%
2006
16th to endDay
26%5%9%23%20%15%
2130
August1st to 15thDay
20%36%17%21%30%
2130
16th to endDay
19%36%17%30%23%
2126
September1st to 15thDay
20%2412%24%35%
1815
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
17%117%29%42%
1901
16th to endNight
7%116%22%61%
1531
May1st to 15thNight
10%115%24%56%
1485
16th to endNight
9%15%18%65%
1541
June1st to 15thNight
7%1314%72%
1485
16th to endNight
8%1127%78%
1485
July1st to 15thNight
18%38%16%15%37%
1395
16th to endNight
21%5%10%21%22%19%
1467
August1st to 15thNight
19%36%20%18%30%
1476
16th to endNight
22%37%13%24%28%
1722
September1st to 15thNight
18%37%17%20%33%
1815
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
6%11%25%30%20%5%
239
16th to endDay
412%37%30%11%4
210
May1st to 15thDay
210%26%38%15%5%
228
16th to endDay
2426%34%24%7%
266
June1st to 15thDay
1325%38%23%7%
255
16th to endDay
112%40%34%9%
255
July1st to 15thDay
118%44%35%8%
245
16th to endDay
21330%42%18%
271
August1st to 15thDay
21333%45%14%
255
16th to endDay
15%28%48%14%
268
September1st to 15thDay
8%9%34%38%9%
255
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
3318%46%25%2
691
16th to endNight
1422%45%22%2
502
May1st to 15thNight
1318%46%28%2
495
16th to endNight
2214%44%34%1
515
June1st to 15thNight
111%55%28%1
495
16th to endNight
16%46%43%2
495
July1st to 15thNight
15%34%53%3
465
16th to endNight
11226%60%6%
522
August1st to 15thNight
2326%59%8%
494
16th to endNight
2324%61%8%
617
September1st to 15thNight
216%28%54%6%
660
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 2017-04-09 03:54:17. Version ac04

Copyright 2017 A. Danko


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