Quartzsite
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Quartzsite clear sky chart from 2005-11-05 to 2017-09-22.

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%
15920
39%
47000
33%
15880
83%
15880
61%
21070

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
75%
720
34%
2327
34%
716
80%
716
48%
1095
January16th to endNight
68%
768
40%
2452
37%
768
77%
768
49%
1173
February1st to 15thNight
73%
698
40%
2111
36%
698
82%
698
56%
971
February16th to endNight
65%
632
36%
1895
36%
632
72%
632
48%
942
March1st to 15thNight
70%
720
39%
2061
33%
720
80%
720
61%
933
March16th to endNight
70%
768
38%
2112
29%
768
78%
768
59%
1007
April1st to 15thNight
62%
719
36%
1901
19%
719
72%
719
63%
905
April16th to endNight
68%
624
47%
1704
26%
624
81%
624
79%
703
May1st to 15thNight
73%
539
41%
1619
28%
539
81%
539
71%
646
May16th to endNight
75%
561
40%
1684
28%
561
81%
561
75%
660
June1st to 15thNight
81%
540
36%
1620
30%
540
84%
540
76%
637
June16th to endNight
89%
540
37%
1620
32%
540
91%
540
82%
606
July1st to 15thNight
87%
510
30%
1530
26%
510
88%
510
60%
689
July16th to endNight
84%
564
32%
1593
26%
531
86%
531
52%
780
August1st to 15thNight
87%
578
37%
1650
28%
575
89%
575
62%
761
August16th to endNight
87%
764
42%
1910
30%
764
88%
764
64%
968
September1st to 15thNight
86%
720
36%
1968
31%
720
88%
720
64%
925
September16th to endNight
86%
683
47%
1890
39%
683
91%
683
78%
796
October1st to 15thNight
78%
660
45%
1815
37%
660
84%
660
68%
825
October16th to endNight
85%
704
46%
2106
42%
704
90%
704
70%
866
November1st to 15thNight
81%
700
40%
2256
40%
700
87%
700
62%
946
November16th to endNight
77%
720
43%
2340
43%
720
84%
720
62%
978
December1st to 15thNight
75%
720
38%
2340
37%
720
81%
720
52%
1066
December16th to endNight
70%
768
38%
2496
36%
768
77%
768
46%
1192

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
212212235%74%
47880
Night
2112212235%74%
47197
TransparencyDay
13%2311%25%43%
47575
Night
14%2311%24%44%
47003
SeeingDay
3416%34%31%9%
5674
Night
3212%35%38%8%
15929

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
3212312246%68%
1611
16th to endDay
5%13212345%68%
1770
February1st to 15thDay
312313346%68%
1751
16th to endDay
3213323346%65%
1579
March1st to 15thDay
31222336%72%
1899
16th to endDay
1112212335%75%
2112
April1st to 15thDay
121212346%72%
2044
16th to endDay
1111125%83%
2254
May1st to 15thDay
111223481%
2331
16th to endDay
111111385%
2429
June1st to 15thDay
11111386%
2340
16th to endDay
11111287%
2340
July1st to 15thDay
1112213335%71%
2340
16th to endDay
5%2123245%6%8%57%
2467
August1st to 15thDay
2112323446%67%
2298
16th to endDay
322322345%69%
2292
September1st to 15thDay
3213213345%69%
1991
16th to endDay
11122483%
1882
October1st to 15thDay
1111123479%
1815
16th to endDay
221123480%
1766
November1st to 15thDay
12111323477%
1601
16th to endDay
311112235%75%
1620
December1st to 15thDay
3213323446%64%
1620
16th to endDay
3213213447%64%
1728
January1st to 15thNight
3213322346%67%
2327
16th to endNight
5%312312235%67%
2452
February1st to 15thNight
2212212336%70%
2101
16th to endNight
5%212313345%64%
1895
March1st to 15thNight
221112346%72%
2061
16th to endNight
111231333472%
2112
April1st to 15thNight
121221223475%
1901
16th to endNight
1112386%
1704
May1st to 15thNight
1111123481%
1619
16th to endNight
1111111286%
1684
June1st to 15thNight
1111112483%
1620
16th to endNight
11387%
1620
July1st to 15thNight
21121246%5%70%
1620
16th to endNight
31123245%6%8%59%
1701
August1st to 15thNight
212212346%72%
1659
16th to endNight
212213347%70%
1910
September1st to 15thNight
112212445%72%
1968
16th to endNight
111112384%
1890
October1st to 15thNight
111112225%78%
1815
16th to endNight
1112235%79%
2106
November1st to 15thNight
1112112225%76%
2256
16th to endNight
221221122476%
2340
December1st to 15thNight
3212222445%67%
2340
16th to endNight
4312323346%65%
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%2314%33%26%
1612
16th to endDay
19%25%14%29%27%
1770
February1st to 15thDay
16%2414%29%32%
1751
16th to endDay
21%2313%32%26%
1579
March1st to 15thDay
14%229%29%41%
1899
16th to endDay
14%1212%30%37%
2112
April1st to 15thDay
13%229%30%41%
2044
16th to endDay
7%127%29%51%
2254
May1st to 15thDay
8%128%25%53%
2331
16th to endDay
7%25%23%60%
2432
June1st to 15thDay
7%316%71%
2340
16th to endDay
6%137%80%
2340
July1st to 15thDay
14%3411%16%48%
2201
16th to endDay
22%5%7%19%22%22%
2312
August1st to 15thDay
17%35%13%23%35%
2283
16th to endDay
16%3411%29%34%
2292
September1st to 15thDay
18%3412%21%39%
1991
16th to endDay
7%12420%63%
1882
October1st to 15thDay
9%138%27%48%
1815
16th to endDay
9%139%20%54%
1766
November1st to 15thDay
12%113%29%41%
1601
16th to endDay
12%1312%30%39%
1620
December1st to 15thDay
20%25%17%27%26%
1620
16th to endDay
20%35%22%29%18%
1728
January1st to 15thNight
19%4311%26%34%
2327
16th to endNight
21%1314%25%33%
2452
February1st to 15thNight
16%2315%24%36%
2112
16th to endNight
21%2413%26%31%
1895
March1st to 15thNight
13%2310%26%43%
2061
16th to endNight
16%1310%28%38%
2112
April1st to 15thNight
14%138%31%40%
1901
16th to endNight
5%129%25%54%
1704
May1st to 15thNight
8%126%27%53%
1620
16th to endNight
7%17%25%57%
1685
June1st to 15thNight
7%11316%69%
1620
16th to endNight
5%127%81%
1620
July1st to 15thNight
14%35%11%18%46%
1530
16th to endNight
18%49%20%21%24%
1593
August1st to 15thNight
13%3211%28%39%
1650
16th to endNight
14%3411%28%37%
1910
September1st to 15thNight
13%35%13%25%39%
1968
16th to endNight
7%125%18%64%
1890
October1st to 15thNight
11%228%24%50%
1815
16th to endNight
9%238%18%57%
2106
November1st to 15thNight
13%119%25%47%
2256
16th to endNight
14%1210%26%44%
2340
December1st to 15thNight
17%35%13%29%30%
2340
16th to endNight
21%35%18%27%23%
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
14%25%38%17%3
90
16th to endDay
46%22%28%29%8%
138
February1st to 15thDay
4424%28%30%6%
266
16th to endDay
6%13%23%32%22%1
238
March1st to 15thDay
411%17%32%28%5%
270
16th to endDay
211%24%28%25%7%
288
April1st to 15thDay
410%24%34%18%7%
269
16th to endDay
212%35%26%17%5%
270
May1st to 15thDay
36%21%38%21%7%
288
16th to endDay
5%23%42%22%6%
330
June1st to 15thDay
1220%40%29%6%
315
16th to endDay
111%42%31%13%
315
July1st to 15thDay
6%39%40%11%
305
16th to endDay
4232%41%18%
327
August1st to 15thDay
2433%41%17%
315
16th to endDay
3232%43%17%
332
September1st to 15thDay
312%36%36%9%
315
16th to endDay
3115%32%36%10%
280
October1st to 15thDay
17%19%31%32%7%
255
16th to endDay
22428%46%14%
102
November1st to 15thDay
2112%34%38%11%
90
16th to endDay
15%23%41%24%4
90
December1st to 15thDay
3113%32%40%10%
90
16th to endDay
5%7%10%45%29%2
96
January1st to 15thNight
4211%39%34%8%
720
16th to endNight
6%214%37%32%5%
768
February1st to 15thNight
3313%38%34%6%
704
16th to endNight
5%5%17%41%24%6%
632
March1st to 15thNight
35%18%36%29%7%
720
16th to endNight
2417%37%29%9%
768
April1st to 15thNight
2425%34%28%4
719
16th to endNight
1423%38%27%4
624
May1st to 15thNight
1419%38%31%4
540
16th to endNight
1217%42%31%4
563
June1st to 15thNight
1112%46%34%3
540
16th to endNight
7%39%47%5%
540
July1st to 15thNight
2432%54%5%
510
16th to endNight
3229%55%8%
564
August1st to 15thNight
3325%56%10%
578
16th to endNight
3224%53%15%
764
September1st to 15thNight
16%27%49%14%
720
16th to endNight
19%29%46%12%
683
October1st to 15thNight
2114%36%38%6%
660
16th to endNight
9%34%41%13%
704
November1st to 15thNight
1110%39%37%9%
700
16th to endNight
3111%33%36%13%
720
December1st to 15thNight
4212%38%36%5%
720
16th to endNight
6%412%40%30%5%
768
Page generated at 2017-09-23 03:43:37. Version ac04

Copyright 2017 A. Danko


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