This page made possible by the sponsorship of: Desert Pines Observatory.

Desert Pines Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Desert Pines Observatory clear sky chart from 2005-11-05 to 2017-05-24.

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
76%
15220
37%
45835
33%
15182
81%
15182
55%
21497

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
72%
718
33%
2327
34%
716
77%
716
50%
1082
January16th to endNight
68%
768
35%
2496
35%
768
75%
768
42%
1272
February1st to 15thNight
74%
699
37%
2202
37%
699
79%
699
53%
1019
February16th to endNight
66%
632
38%
1838
35%
632
73%
632
51%
930
March1st to 15thNight
69%
720
39%
1980
32%
720
76%
720
58%
961
March16th to endNight
75%
768
40%
2112
29%
768
82%
768
63%
995
April1st to 15thNight
70%
686
35%
1945
27%
686
77%
686
58%
921
April16th to endNight
74%
540
46%
1779
41%
540
83%
540
72%
654
May1st to 15thNight
75%
539
41%
1619
32%
539
83%
539
73%
641
May16th to endNight
77%
540
41%
1621
34%
540
81%
540
74%
636
June1st to 15thNight
83%
495
37%
1485
32%
495
84%
495
70%
614
June16th to endNight
85%
495
31%
1485
27%
495
86%
495
65%
637
July1st to 15thNight
83%
465
23%
1395
20%
465
83%
465
43%
738
July16th to endNight
83%
522
21%
1467
17%
489
83%
489
37%
839
August1st to 15thNight
86%
494
28%
1476
27%
491
86%
491
47%
760
August16th to endNight
86%
551
29%
1718
30%
551
86%
551
43%
914
September1st to 15thNight
79%
660
32%
1815
28%
660
80%
660
46%
1013
September16th to endNight
82%
656
42%
1815
33%
656
86%
656
66%
832
October1st to 15thNight
80%
660
41%
1914
34%
660
85%
660
66%
853
October16th to endNight
86%
704
44%
2112
40%
704
89%
704
69%
893
November1st to 15thNight
81%
700
43%
2100
39%
700
85%
700
68%
889
November16th to endNight
74%
720
39%
2298
38%
720
79%
720
53%
1055
December1st to 15thNight
74%
720
38%
2340
40%
720
77%
720
51%
1073
December16th to endNight
68%
768
35%
2496
35%
768
72%
768
42%
1276

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
4212323346%65%
46433
Night
4212223345%67%
46031
TransparencyDay
19%2411%24%36%
46128
Night
18%25%13%25%35%
45837
SeeingDay
6%8%22%34%21%6%
4959
Night
4111%39%36%6%
15230

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%213323336%65%
1611
16th to endDay
7%323313336%61%
1728
February1st to 15thDay
6%212212335%67%
1658
16th to endDay
8%313223236%61%
1634
March1st to 15thDay
5%212222346%67%
1980
16th to endDay
31212233474%
2112
April1st to 15thDay
3111212436%71%
2001
16th to endDay
21111112481%
2178
May1st to 15thDay
1112223478%
2331
16th to endDay
11111212383%
2335
June1st to 15thDay
2111113479%
2145
16th to endDay
11212345%74%
2145
July1st to 15thDay
32245%46%8%8%9%44%
2145
16th to endDay
6%436%6%45%6%9%11%32%
2285
August1st to 15thDay
5%326%6%36%6%7%9%43%
2145
16th to endDay
3215%5%35%6%7%8%48%
2129
September1st to 15thDay
6%3135%35%5%5%7%51%
1815
16th to endDay
32221333472%
1815
October1st to 15thDay
211213235%73%
1715
16th to endDay
111212235%78%
1760
November1st to 15thDay
111112245%76%
1759
16th to endDay
4212212335%70%
1659
December1st to 15thDay
8%2232225%6%63%
1620
16th to endDay
7%313313346%62%
1728
January1st to 15thNight
6%22221233467%
2327
16th to endNight
7%213324445%59%
2496
February1st to 15thNight
5%213213235%67%
2191
16th to endNight
7%312223346%61%
1838
March1st to 15thNight
6%211212335%68%
1980
16th to endNight
2211312235%73%
2112
April1st to 15thNight
311222424469%
1945
16th to endNight
211112285%
1779
May1st to 15thNight
1112245%78%
1619
16th to endNight
1111111385%
1621
June1st to 15thNight
111111222380%
1485
16th to endNight
121221222477%
1485
July1st to 15thNight
2313435%5%8%11%51%
1485
16th to endNight
32145%45%7%9%14%40%
1575
August1st to 15thNight
2214235%5%6%9%57%
1485
16th to endNight
2213445%6%8%10%50%
1718
September1st to 15thNight
422442445%8%56%
1815
16th to endNight
22121234474%
1815
October1st to 15thNight
21221233475%
1914
16th to endNight
11121212379%
2112
November1st to 15thNight
121212325%76%
2100
16th to endNight
6%212212335%68%
2298
December1st to 15thNight
7%212112346%65%
2340
16th to endNight
9%314323335%59%
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
20%2413%27%31%
1612
16th to endDay
25%2315%24%29%
1728
February1st to 15thDay
19%1312%27%33%
1658
16th to endDay
23%1313%30%27%
1634
March1st to 15thDay
18%127%31%38%
1980
16th to endDay
15%138%30%41%
2112
April1st to 15thDay
13%116%37%39%
2001
16th to endDay
9%17%23%56%
2178
May1st to 15thDay
10%126%22%57%
2331
16th to endDay
8%27%23%57%
2338
June1st to 15thDay
10%318%66%
2145
16th to endDay
12%236%16%59%
2145
July1st to 15thDay
29%7%12%14%15%19%
2006
16th to endDay
40%6%16%21%12%3
2130
August1st to 15thDay
32%6%11%16%17%15%
2130
16th to endDay
29%7%10%19%18%14%
2129
September1st to 15thDay
28%5%7%19%17%21%
1815
16th to endDay
15%228%32%38%
1815
October1st to 15thDay
13%1411%24%43%
1715
16th to endDay
11%38%26%48%
1760
November1st to 15thDay
10%211%33%40%
1759
16th to endDay
17%139%28%39%
1659
December1st to 15thDay
21%1416%31%24%
1620
16th to endDay
23%15%20%31%17%
1728
January1st to 15thNight
20%2413%27%30%
2327
16th to endNight
26%2315%27%24%
2496
February1st to 15thNight
19%1415%25%33%
2202
16th to endNight
22%1413%31%26%
1838
March1st to 15thNight
18%1310%26%41%
1980
16th to endNight
15%1210%31%38%
2112
April1st to 15thNight
17%128%34%36%
1945
16th to endNight
8%16%26%56%
1779
May1st to 15thNight
8%138%26%52%
1620
16th to endNight
8%16%23%59%
1622
June1st to 15thNight
10%11318%64%
1485
16th to endNight
13%12417%60%
1485
July1st to 15thNight
22%6%15%18%16%20%
1395
16th to endNight
26%8%22%24%12%3
1467
August1st to 15thNight
20%6%14%22%17%18%
1476
16th to endNight
24%5%14%21%18%15%
1718
September1st to 15thNight
24%5%8%23%20%18%
1815
16th to endNight
13%2211%31%39%
1815
October1st to 15thNight
13%1314%25%41%
1914
16th to endNight
11%1211%23%49%
2112
November1st to 15thNight
12%1212%32%38%
2100
16th to endNight
19%1311%23%40%
2298
December1st to 15thNight
20%1416%30%25%
2340
16th to endNight
27%16%16%28%19%
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
16%217%45%14%3
90
16th to endDay
9%115%37%28%8%
96
February1st to 15thDay
7%9%19%38%23%2
173
16th to endDay
13%14%36%23%10%2
238
March1st to 15thDay
8%14%25%30%13%7%
270
16th to endDay
417%33%22%16%4
288
April1st to 15thDay
8%17%29%26%13%4
269
16th to endDay
5%20%32%27%11%2
270
May1st to 15thDay
415%36%26%11%4
288
16th to endDay
18%36%38%11%2
301
June1st to 15thDay
6%6%30%39%13%3
255
16th to endDay
3116%49%20%7%
255
July1st to 15thDay
5%211%44%30%6%
245
16th to endDay
8%29%35%29%15%
271
August1st to 15thDay
7%6%41%31%11%
255
16th to endDay
126%38%37%13%
268
September1st to 15thDay
10%117%38%23%7%
255
16th to endDay
8%423%32%24%5%
255
October1st to 15thDay
19%20%38%20%9%
155
16th to endDay
316%28%51%10%
96
November1st to 15thDay
310%18%35%25%6%
90
16th to endDay
5%6%25%38%22%1
90
December1st to 15thDay
6%15%30%42%5%
90
16th to endDay
19%6%20%33%18%1
96
January1st to 15thNight
8%13%45%27%4
720
16th to endNight
8%213%44%26%4
768
February1st to 15thNight
6%111%46%28%5%
704
16th to endNight
7%218%48%19%2
632
March1st to 15thNight
6%218%41%25%5%
720
16th to endNight
3313%44%31%4
768
April1st to 15thNight
4415%50%22%2
686
16th to endNight
2418%47%24%2
540
May1st to 15thNight
417%44%29%2
540
16th to endNight
2216%43%33%1
542
June1st to 15thNight
2110%46%36%2
495
16th to endNight
16%36%50%4
495
July1st to 15thNight
21322%62%7%
465
16th to endNight
3116%63%13%
522
August1st to 15thNight
4115%66%13%
494
16th to endNight
2120%61%12%
551
September1st to 15thNight
5%15%24%50%12%
660
16th to endNight
39%33%43%9%
656
October1st to 15thNight
2112%42%35%6%
660
16th to endNight
27%41%38%9%
704
November1st to 15thNight
211%42%37%6%
700
16th to endNight
7%111%42%31%5%
720
December1st to 15thNight
8%112%41%30%5%
720
16th to endNight
9%212%47%20%6%
768
Page generated at 2017-05-25 10:27:33. Version ac04

Copyright 2017 A. Danko


Desert Pines Observatory Clear Sky Chart | Charts Home