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 2018-03-21.

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%
16434
38%
49185
34%
16395
82%
16395
58%
22538

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%
778
34%
2522
34%
776
79%
776
48%
1203
January16th to endNight
68%
832
39%
2704
37%
832
77%
832
47%
1313
February1st to 15thNight
73%
759
38%
2342
36%
758
82%
758
56%
1072
February16th to endNight
70%
684
36%
2051
37%
684
74%
684
47%
1046
March1st to 15thNight
70%
780
41%
2155
34%
780
77%
780
61%
1029
March16th to endNight
75%
792
42%
2178
33%
792
83%
792
66%
995
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
82%
720
34%
1980
30%
720
84%
720
56%
992
September16th to endNight
85%
716
45%
1980
37%
716
89%
716
71%
868
October1st to 15thNight
81%
720
42%
2046
35%
720
85%
720
70%
888
October16th to endNight
86%
768
47%
2304
42%
768
90%
768
72%
937
November1st to 15thNight
85%
760
41%
2345
40%
760
88%
760
64%
998
November16th to endNight
79%
780
43%
2535
43%
780
83%
780
57%
1099
December1st to 15thNight
74%
780
37%
2535
37%
780
79%
780
50%
1178
December16th to endNight
72%
832
39%
2704
40%
832
76%
832
44%
1329

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%
49661
Night
3212213345%70%
49383
TransparencyDay
15%2312%25%41%
49356
Night
16%1311%23%43%
49189
SeeingDay
4315%32%32%12%
6119
Night
4110%42%37%4
16444

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
4313312336%67%
1746
16th to endDay
6%213212235%67%
1872
February1st to 15thDay
3313212337%67%
1846
16th to endDay
5%313312346%64%
1709
March1st to 15thDay
3211213346%68%
2135
16th to endDay
2112213235%72%
2173
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
4212313347%64%
1980
16th to endDay
11111122381%
1980
October1st to 15thDay
11111222478%
1914
16th to endDay
1121123479%
1920
November1st to 15thDay
12212235%75%
1841
16th to endDay
4112212135%73%
1755
December1st to 15thDay
421241235%6%63%
1755
16th to endDay
5%314312446%61%
1872
January1st to 15thNight
5%31232334465%
2522
16th to endNight
7%313213235%65%
2704
February1st to 15thNight
3312212335%69%
2333
16th to endNight
5%213324435%63%
2051
March1st to 15thNight
4212212235%70%
2155
16th to endNight
312112246%73%
2178
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%61%
1980
16th to endNight
11111223479%
1980
October1st to 15thNight
211112135%78%
2046
16th to endNight
11211223479%
2304
November1st to 15thNight
1211122235%74%
2345
16th to endNight
32321222473%
2535
December1st to 15thNight
5%223213346%65%
2535
16th to endNight
6%313423336%62%
2704

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
20%2414%29%27%
1747
16th to endDay
20%1216%27%31%
1872
February1st to 15thDay
19%1416%27%30%
1846
16th to endDay
21%2216%30%25%
1709
March1st to 15thDay
17%1110%30%37%
2135
16th to endDay
16%1210%32%36%
2173
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%35%
1980
16th to endDay
9%1426%57%
1980
October1st to 15thDay
11%119%25%50%
1914
16th to endDay
9%137%29%48%
1920
November1st to 15thDay
12%1114%31%39%
1841
16th to endDay
15%1110%30%41%
1755
December1st to 15thDay
23%2417%25%27%
1755
16th to endDay
23%1422%29%17%
1872
January1st to 15thNight
22%1312%25%33%
2522
16th to endNight
23%1112%26%33%
2704
February1st to 15thNight
18%1414%24%37%
2344
16th to endNight
24%1210%28%32%
2051
March1st to 15thNight
16%1110%24%45%
2155
16th to endNight
13%129%30%43%
2178
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%
1980
16th to endNight
10%15%20%61%
1980
October1st to 15thNight
11%19%21%54%
2046
16th to endNight
9%129%16%60%
2304
November1st to 15thNight
13%1110%28%44%
2345
16th to endNight
16%128%24%46%
2535
December1st to 15thNight
20%1313%26%33%
2535
16th to endNight
24%2415%29%23%
2704

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
18%8%35%27%8%
135
16th to endDay
6%112%34%30%14%
144
February1st to 15thDay
4214%32%32%12%
271
16th to endDay
8%5%26%34%20%3
290
March1st to 15thDay
5%5%20%30%26%11%
330
16th to endDay
27%27%30%23%9%
311
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
6%8%32%40%10%
315
16th to endDay
3115%33%32%14%
315
October1st to 15thDay
2217%29%38%8%
249
16th to endDay
35%23%40%26%
144
November1st to 15thDay
19%35%42%10%
135
16th to endDay
6%16%34%29%13%
135
December1st to 15thDay
311%31%42%9%
135
16th to endDay
7%215%30%32%11%
144
January1st to 15thNight
7%111%47%28%3
780
16th to endNight
8%114%46%25%3
832
February1st to 15thNight
5%213%45%29%3
764
16th to endNight
6%214%52%22%2
684
March1st to 15thNight
6%116%42%30%2
780
16th to endNight
4213%45%30%3
792
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%
720
16th to endNight
217%38%44%5%
716
October1st to 15thNight
210%44%38%2
720
16th to endNight
18%39%43%5%
768
November1st to 15thNight
216%47%37%4
760
16th to endNight
5%9%42%37%4
780
December1st to 15thNight
6%111%44%34%1
780
16th to endNight
7%29%48%28%3
832
Page generated at 2018-03-22 08:34:20. Version ac04

Copyright 2018 A. Danko


Sun City West Clear Sky Chart |Charts Home