Cottonwood Spring Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cottonwood Spring Campground clear sky chart from 2005-11-05 to 2018-02-22.

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
75%
16706
40%
48912
32%
16665
82%
16665
61%
21835

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
67%
780
35%
2522
32%
776
76%
776
45%
1206
January16th to endNight
64%
832
41%
2574
32%
832
77%
832
47%
1240
February1st to 15thNight
67%
759
40%
2290
34%
758
79%
758
52%
1061
February16th to endNight
61%
660
39%
1979
35%
660
71%
660
48%
976
March1st to 15thNight
66%
720
37%
2118
33%
720
76%
720
55%
980
March16th to endNight
68%
768
38%
2109
29%
768
77%
768
57%
1021
April1st to 15thNight
59%
719
39%
1799
18%
719
71%
719
62%
876
April16th to endNight
65%
693
44%
1773
21%
693
76%
693
71%
793
May1st to 15thNight
72%
539
43%
1619
29%
539
79%
539
75%
614
May16th to endNight
76%
561
40%
1685
29%
561
81%
561
75%
652
June1st to 15thNight
80%
540
36%
1620
29%
540
83%
540
78%
619
June16th to endNight
85%
540
38%
1620
32%
540
86%
540
80%
621
July1st to 15thNight
89%
510
31%
1530
27%
510
89%
510
63%
671
July16th to endNight
85%
564
36%
1593
31%
531
86%
531
57%
737
August1st to 15thNight
90%
681
38%
1755
26%
678
91%
678
71%
831
August16th to endNight
90%
764
43%
1910
31%
764
90%
764
71%
928
September1st to 15thNight
89%
720
39%
1911
32%
720
90%
720
71%
865
September16th to endNight
88%
716
50%
1980
43%
716
93%
716
83%
796
October1st to 15thNight
78%
720
45%
1980
37%
720
85%
720
71%
862
October16th to endNight
83%
768
48%
2301
45%
768
90%
768
70%
941
November1st to 15thNight
76%
760
39%
2470
36%
760
85%
760
62%
1013
November16th to endNight
75%
780
44%
2535
44%
780
82%
780
58%
1067
December1st to 15thNight
68%
780
37%
2535
34%
780
76%
780
48%
1163
December16th to endNight
64%
832
39%
2704
34%
832
75%
832
43%
1302

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
222212235%74%
49337
Night
2212212335%74%
49109
TransparencyDay
13%2211%26%43%
49032
Night
13%2212%26%42%
48915
SeeingDay
49%22%35%22%5%
6327
Night
3412%29%37%12%
16714

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
3312313246%65%
1746
16th to endDay
431232235%6%65%
1999
February1st to 15thDay
221231325%6%68%
1901
16th to endDay
23145%23346%61%
1641
March1st to 15thDay
212112447%70%
1840
16th to endDay
1212212237%72%
2112
April1st to 15thDay
1212312345%70%
2149
16th to endDay
11111126%81%
2187
May1st to 15thDay
1121123480%
2331
16th to endDay
11122384%
2429
June1st to 15thDay
1111112384%
2340
16th to endDay
1111287%
2340
July1st to 15thDay
322222247%70%
2340
16th to endDay
2312223346%66%
2467
August1st to 15thDay
112112245%74%
2193
16th to endDay
32221223473%
2292
September1st to 15thDay
112112335%74%
2049
16th to endDay
111111385%
1980
October1st to 15thDay
111121122480%
1980
16th to endDay
1121222479%
1920
November1st to 15thDay
221222232473%
1719
16th to endDay
2212212336%71%
1755
December1st to 15thDay
321222345%8%62%
1755
16th to endDay
4313224347%62%
1872
January1st to 15thNight
2313323446%63%
2522
16th to endNight
4312223335%65%
2574
February1st to 15thNight
1312213345%69%
2281
16th to endNight
22132245%5%7%62%
1979
March1st to 15thNight
2112213447%69%
2118
16th to endNight
111221245%6%69%
2109
April1st to 15thNight
121213135%75%
1799
16th to endNight
1111212384%
1773
May1st to 15thNight
1135%84%
1619
16th to endNight
1122286%
1684
June1st to 15thNight
11111386%
1620
16th to endNight
1111287%
1620
July1st to 15thNight
11221323474%
1620
16th to endNight
3212213446%66%
1701
August1st to 15thNight
111113335%75%
1764
16th to endNight
211212225%77%
1910
September1st to 15thNight
211132479%
1911
16th to endNight
11111190%
1980
October1st to 15thNight
2111235%80%
1980
16th to endNight
111133381%
2301
November1st to 15thNight
1111212235%76%
2470
16th to endNight
2212212235%74%
2535
December1st to 15thNight
3212313347%65%
2535
16th to endNight
4213313346%64%
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
19%3416%29%26%
1747
16th to endDay
19%2316%30%27%
1999
February1st to 15thDay
16%2413%29%33%
1901
16th to endDay
22%3217%29%24%
1641
March1st to 15thDay
13%3114%30%37%
1840
16th to endDay
14%1116%34%30%
2112
April1st to 15thDay
15%2211%34%34%
2149
16th to endDay
7%1111%33%44%
2187
May1st to 15thDay
8%118%30%49%
2331
16th to endDay
7%119%27%53%
2432
June1st to 15thDay
7%15%18%67%
2340
16th to endDay
6%138%80%
2340
July1st to 15thDay
14%228%20%51%
2201
16th to endDay
18%3318%24%31%
2312
August1st to 15thDay
12%229%25%47%
2178
16th to endDay
15%228%25%45%
2292
September1st to 15thDay
11%2312%21%48%
2049
16th to endDay
6%11423%63%
1980
October1st to 15thDay
10%128%25%51%
1980
16th to endDay
10%229%20%54%
1920
November1st to 15thDay
15%2112%29%38%
1719
16th to endDay
13%2312%27%39%
1755
December1st to 15thDay
17%4418%24%30%
1755
16th to endDay
21%26%19%28%21%
1872
January1st to 15thNight
21%3214%28%29%
2522
16th to endNight
20%3217%22%33%
2574
February1st to 15thNight
16%2313%26%36%
2292
16th to endNight
19%4315%30%26%
1979
March1st to 15thNight
14%3313%32%33%
2118
16th to endNight
14%2314%31%31%
2109
April1st to 15thNight
13%1313%35%33%
1799
16th to endNight
7%1212%31%44%
1773
May1st to 15thNight
5%1112%31%47%
1620
16th to endNight
6%119%33%47%
1685
June1st to 15thNight
6%18%19%64%
1620
16th to endNight
6%37%80%
1620
July1st to 15thNight
13%217%20%54%
1530
16th to endNight
16%25%15%28%30%
1593
August1st to 15thNight
11%2112%25%47%
1755
16th to endNight
11%128%24%51%
1910
September1st to 15thNight
9%2211%20%52%
1911
16th to endNight
5%15%22%65%
1980
October1st to 15thNight
9%219%28%48%
1980
16th to endNight
8%228%20%57%
2301
November1st to 15thNight
12%2211%30%41%
2470
16th to endNight
14%2112%28%40%
2535
December1st to 15thNight
19%35%15%25%32%
2535
16th to endNight
21%36%16%28%24%
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
15%420%32%23%2
135
16th to endDay
6%14%26%31%16%4
271
February1st to 15thDay
410%31%30%19%3
326
16th to endDay
11%14%29%29%14%1
264
March1st to 15thDay
5%16%24%31%20%2
270
16th to endDay
417%29%28%17%1
288
April1st to 15thDay
8%19%31%22%13%3
269
16th to endDay
424%29%27%12%1
270
May1st to 15thDay
312%33%34%11%4
288
16th to endDay
211%32%35%13%5%
330
June1st to 15thDay
27%30%35%18%5%
315
16th to endDay
3222%39%20%10%
315
July1st to 15thDay
212%44%27%11%
305
16th to endDay
28%42%31%14%
327
August1st to 15thDay
114%41%28%12%
315
16th to endDay
28%41%33%12%
332
September1st to 15thDay
1416%46%24%6%
315
16th to endDay
19%18%38%28%2
315
October1st to 15thDay
38%24%42%20%
315
16th to endDay
3417%31%36%6%
213
November1st to 15thDay
18%18%31%34%5%
135
16th to endDay
7%10%20%27%28%5%
135
December1st to 15thDay
7%14%10%36%28%2
135
16th to endDay
10%8%13%32%29%4
144
January1st to 15thNight
5%414%35%29%10%
780
16th to endNight
7%6%16%32%28%8%
832
February1st to 15thNight
37%14%34%31%8%
764
16th to endNight
37%22%37%21%7%
660
March1st to 15thNight
38%17%32%29%9%
720
16th to endNight
27%16%32%29%11%
768
April1st to 15thNight
310%22%31%25%7%
719
16th to endNight
19%20%28%29%9%
693
May1st to 15thNight
16%15%32%35%8%
540
16th to endNight
16%14%34%35%8%
563
June1st to 15thNight
212%35%39%7%
540
16th to endNight
110%31%47%8%
540
July1st to 15thNight
2225%55%14%
510
16th to endNight
31117%62%12%
564
August1st to 15thNight
1314%61%18%
681
16th to endNight
4111%55%27%
764
September1st to 15thNight
2320%52%20%
720
16th to endNight
117%27%42%19%
716
October1st to 15thNight
2411%35%34%11%
720
16th to endNight
237%29%39%17%
768
November1st to 15thNight
1313%33%34%13%
760
16th to endNight
4411%28%33%17%
780
December1st to 15thNight
5%6%11%36%31%9%
780
16th to endNight
7%8%13%34%27%8%
832
Page generated at 2018-02-23 08:21:40. Version ac04

Copyright 2018 A. Danko


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