Cottonwood Pit Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cottonwood Pit Campground clear sky chart from 2005-11-05 to 2018-01-20.

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
50%
15215
17%
48493
15%
15189
53%
15189
24%
31201

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
36%
776
10%
2716
10%
776
38%
776
13%
2035
January16th to endNight
46%
788
15%
2731
15%
788
49%
788
17%
1873
February1st to 15thNight
38%
698
8%
2288
7%
696
40%
696
14%
1712
February16th to endNight
37%
632
14%
1909
13%
632
40%
632
16%
1413
March1st to 15thNight
36%
720
9%
2142
6%
720
40%
720
14%
1648
March16th to endNight
34%
768
10%
2010
6%
768
37%
768
17%
1515
April1st to 15thNight
39%
719
12%
1799
6%
719
40%
719
19%
1354
April16th to endNight
45%
672
15%
1752
8%
672
48%
672
27%
1186
May1st to 15thNight
51%
374
19%
1454
20%
374
57%
374
28%
784
May16th to endNight
54%
374
12%
1496
15%
374
58%
374
20%
916
June1st to 15thNight
55%
360
14%
1440
17%
360
62%
360
25%
814
June16th to endNight
61%
360
20%
1440
29%
360
68%
360
37%
665
July1st to 15thNight
76%
340
21%
1360
31%
340
83%
340
53%
526
July16th to endNight
74%
376
34%
1416
42%
354
84%
354
60%
500
August1st to 15thNight
78%
429
33%
1501
31%
427
84%
427
54%
628
August16th to endNight
76%
753
38%
1899
25%
753
79%
753
68%
915
September1st to 15thNight
78%
720
37%
1800
22%
720
80%
720
68%
881
September16th to endNight
65%
716
30%
1933
25%
716
67%
716
42%
1109
October1st to 15thNight
55%
720
20%
2160
19%
720
60%
720
33%
1281
October16th to endNight
53%
768
21%
2406
21%
768
56%
768
24%
1561
November1st to 15thNight
41%
760
14%
2470
14%
760
44%
760
16%
1794
November16th to endNight
38%
780
10%
2729
9%
780
42%
780
15%
1944
December1st to 15thNight
42%
780
11%
2730
11%
780
44%
780
16%
1936
December16th to endNight
33%
832
11%
2912
10%
832
36%
832
11%
2211

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
9%9%46%5%24446%42%
49060
Night
8%9%36%5%3445%6%42%
48661
Cloud CoverDay
8%10%46%5%24445%42%
49060
Night
7%9%46%5%3445%6%41%
48665
TransparencyDay
43%49%19%16%6%
48731
Night
42%5%12%20%14%4
48494
SeeingDay
16%16%26%24%12%3
5874
Night
13%10%17%30%22%4
15227

By Month

Percentage Cloud Cover NW (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
12%13%49%8%36%5%5%6%24%
1552
16th to endDay
11%15%5%6%6%33349%29%
1596
February1st to 15thDay
11%14%6%10%5%3435%6%25%
1576
16th to endDay
8%13%6%9%9%47%5%6%5%24%
1565
March1st to 15thDay
12%15%8%12%7%35%44420%
1818
16th to endDay
10%17%7%10%8%35%44423%
2214
April1st to 15thDay
10%16%7%8%6%45%45%5%25%
2149
16th to endDay
9%12%5%7%5%34446%36%
2207
May1st to 15thDay
8%9%46%5%25%45%6%42%
2494
16th to endDay
13%11%47%7%35%5%45%31%
2615
June1st to 15thDay
13%8%36%43435%7%39%
2520
16th to endDay
7%5%1422335%6%56%
2520
July1st to 15thDay
2113313345%69%
2520
16th to endDay
111221233476%
2657
August1st to 15thDay
2212323346%67%
2448
16th to endDay
212212235%73%
2304
September1st to 15thDay
2212212236%72%
2160
16th to endDay
7%7%25%424446%50%
2024
October1st to 15thDay
11%8%345%345%5%6%42%
1800
16th to endDay
13%8%46%5%24445%38%
1818
November1st to 15thDay
14%13%47%6%2445%6%29%
1719
16th to endDay
12%13%5%8%7%36%5%46%26%
1560
December1st to 15thDay
11%12%5%8%6%35%6%6%6%27%
1560
16th to endDay
15%16%7%10%7%445%46%18%
1664
January1st to 15thNight
9%14%5%8%7%45%6%46%26%
2716
16th to endNight
10%12%47%5%25%46%7%31%
2731
February1st to 15thNight
11%12%5%9%6%345%5%7%27%
2276
16th to endNight
9%13%5%8%6%45%5%5%7%28%
1909
March1st to 15thNight
12%12%5%8%7%37%5%5%6%25%
2142
16th to endNight
8%10%48%7%46%6%7%8%26%
2006
April1st to 15thNight
11%11%5%7%6%25%5%5%6%31%
1799
16th to endNight
7%10%35%43445%7%43%
1752
May1st to 15thNight
6%7%35%42335%7%50%
1454
16th to endNight
8%6%36%6%25%5%5%8%40%
1496
June1st to 15thNight
10%5%25%42436%7%49%
1440
16th to endNight
5%413323437%60%
1440
July1st to 15thNight
211223446%70%
1440
16th to endNight
11111223379%
1512
August1st to 15thNight
221113447%69%
1509
16th to endNight
11221222478%
1899
September1st to 15thNight
11221135%475%
1800
16th to endNight
6%5%14323446%57%
1933
October1st to 15thNight
7%6%25%42335%6%50%
2160
16th to endNight
11%7%37%5%24446%42%
2406
November1st to 15thNight
14%11%36%6%35%5%6%8%28%
2470
16th to endNight
12%10%48%7%45%5%5%6%30%
2729
December1st to 15thNight
11%11%5%6%7%25%45%8%30%
2730
16th to endNight
12%16%5%8%7%35%45%6%23%
2912

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
11%13%5%10%8%35%5%5%5%26%
1552
16th to endDay
10%16%6%7%6%23348%30%
1596
February1st to 15thDay
9%15%8%9%7%3435%6%25%
1576
16th to endDay
8%14%7%8%8%5%6%5%6%5%23%
1565
March1st to 15thDay
9%18%7%12%9%35%44419%
1818
16th to endDay
10%18%7%11%8%35%435%21%
2214
April1st to 15thDay
11%18%7%8%6%3445%5%23%
2149
16th to endDay
10%13%5%7%5%24346%35%
2207
May1st to 15thDay
9%11%36%43445%6%41%
2494
16th to endDay
15%12%37%6%34445%30%
2615
June1st to 15thDay
14%9%25%5%2445%6%38%
2520
16th to endDay
7%5%1422335%6%55%
2520
July1st to 15thDay
2212323445%67%
2520
16th to endDay
111121233475%
2657
August1st to 15thDay
232323346%66%
2448
16th to endDay
222112245%73%
2304
September1st to 15thDay
221221323472%
2160
16th to endDay
8%7%34424345%50%
2024
October1st to 15thDay
11%10%26%5%235%46%41%
1800
16th to endDay
11%9%48%5%34445%38%
1818
November1st to 15thDay
13%15%47%6%3445%6%27%
1719
16th to endDay
7%16%6%8%7%5%5%5%5%6%26%
1560
December1st to 15thDay
9%14%6%9%6%35%5%5%7%27%
1560
16th to endDay
13%19%7%9%6%45%345%20%
1664
January1st to 15thNight
9%14%7%9%7%45%446%25%
2716
16th to endNight
8%13%5%7%6%35%46%6%31%
2731
February1st to 15thNight
9%11%6%9%8%45%5%5%6%26%
2276
16th to endNight
7%12%7%8%6%45%5%5%7%28%
1909
March1st to 15thNight
8%12%5%9%8%46%6%6%6%24%
2142
16th to endNight
7%11%5%9%8%36%7%7%9%25%
2010
April1st to 15thNight
10%13%48%6%35%45%5%30%
1799
16th to endNight
8%10%45%4345%5%7%41%
1752
May1st to 15thNight
7%7%35%33435%6%49%
1454
16th to endNight
9%9%35%4445%5%8%39%
1496
June1st to 15thNight
11%6%144235%47%48%
1440
16th to endNight
4423423246%60%
1440
July1st to 15thNight
11222325%6%70%
1440
16th to endNight
1111213479%
1512
August1st to 15thNight
222213347%68%
1509
16th to endNight
11221222478%
1899
September1st to 15thNight
11221233475%
1800
16th to endNight
5%5%25%324446%56%
1933
October1st to 15thNight
9%7%25%434346%49%
2160
16th to endNight
8%8%28%6%34446%41%
2406
November1st to 15thNight
13%11%36%6%36%5%6%7%28%
2470
16th to endNight
8%11%5%9%8%45%45%5%30%
2729
December1st to 15thNight
7%13%5%9%7%44447%29%
2730
16th to endNight
10%16%6%9%7%45%5%5%6%22%
2912

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
58%6%13%15%6%
1552
16th to endDay
53%5%14%15%7%4
1596
February1st to 15thDay
58%5%15%14%5%1
1576
16th to endDay
59%6%12%15%4
1565
March1st to 15thDay
67%410%11%5%1
1818
16th to endDay
64%412%13%4
2214
April1st to 15thDay
61%411%16%5%
2149
16th to endDay
50%411%22%10%1
2207
May1st to 15thDay
42%411%27%12%1
2494
16th to endDay
55%49%20%8%1
2619
June1st to 15thDay
45%48%25%13%2
2520
16th to endDay
29%29%29%23%5%
2520
July1st to 15thDay
17%37%19%30%20%
2371
16th to endDay
13%2312%36%30%
2490
August1st to 15thDay
18%3423%32%18%
2431
16th to endDay
13%2425%37%16%
2304
September1st to 15thDay
15%2425%33%18%
2160
16th to endDay
34%48%23%22%6%
2024
October1st to 15thDay
42%5%10%20%16%5%
1800
16th to endDay
47%410%21%15%1
1818
November1st to 15thDay
56%5%11%18%6%
1719
16th to endDay
58%412%12%9%1
1560
December1st to 15thDay
54%7%13%16%6%1
1560
16th to endDay
66%411%12%4
1664
January1st to 15thNight
58%6%12%14%7%1
2716
16th to endNight
50%5%11%18%9%4
2731
February1st to 15thNight
56%7%15%12%7%1
2288
16th to endNight
53%7%11%19%6%
1909
March1st to 15thNight
56%7%12%15%42
2142
16th to endNight
50%9%17%18%3
2010
April1st to 15thNight
53%5%12%21%6%
1799
16th to endNight
41%6%18%23%9%1
1752
May1st to 15thNight
33%314%32%14%
1455
16th to endNight
41%6%17%25%8%1
1496
June1st to 15thNight
34%6%13%28%13%2
1440
16th to endNight
24%312%33%19%5%
1440
July1st to 15thNight
15%210%25%29%16%
1360
16th to endNight
10%2417%37%26%
1416
August1st to 15thNight
15%36%26%31%16%
1501
16th to endNight
12%26%25%36%17%
1899
September1st to 15thNight
12%2428%36%15%
1800
16th to endNight
27%49%24%21%11%
1933
October1st to 15thNight
34%412%24%20%4
2160
16th to endNight
43%5%11%18%17%3
2406
November1st to 15thNight
52%7%11%17%10%
2470
16th to endNight
54%5%13%14%11%1
2729
December1st to 15thNight
52%6%14%17%8%
2730
16th to endNight
61%411%15%5%1
2912

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
17%11%23%14%26%6%
90
16th to endDay
23%17%26%22%8%3
99
February1st to 15thDay
23%20%25%20%8%
236
16th to endDay
23%25%31%13%5%
235
March1st to 15thDay
30%26%25%13%4
270
16th to endDay
27%25%31%12%3
288
April1st to 15thDay
22%23%25%17%7%3
269
16th to endDay
21%25%25%16%8%3
270
May1st to 15thDay
21%19%26%21%7%2
288
16th to endDay
23%11%21%23%14%4
330
June1st to 15thDay
16%17%26%21%13%4
315
16th to endDay
9%14%31%26%13%3
315
July1st to 15thDay
6%7%29%33%19%3
305
16th to endDay
110%36%30%15%4
327
August1st to 15thDay
35%31%33%16%10%
315
16th to endDay
49%21%34%20%9%
332
September1st to 15thDay
5%7%28%29%24%4
315
16th to endDay
14%10%24%28%19%2
315
October1st to 15thDay
22%16%17%31%11%1
315
16th to endDay
18%15%23%25%12%4
234
November1st to 15thDay
20%18%28%25%6%
135
16th to endDay
24%24%18%21%11%
90
December1st to 15thDay
21%18%20%18%12%8%
90
16th to endDay
22%15%26%26%8%1
96
January1st to 15thNight
16%15%19%23%22%3
780
16th to endNight
17%11%15%28%22%4
788
February1st to 15thNight
16%13%17%31%18%3
704
16th to endNight
14%16%21%28%16%1
632
March1st to 15thNight
16%17%20%28%15%2
720
16th to endNight
14%19%23%26%14%1
768
April1st to 15thNight
18%15%19%26%16%3
719
16th to endNight
13%12%22%27%20%3
672
May1st to 15thNight
10%7%25%32%21%2
375
16th to endNight
12%5%18%30%27%5%
375
June1st to 15thNight
14%6%17%37%22%1
360
16th to endNight
7%5%19%41%23%1
360
July1st to 15thNight
2115%45%32%3
340
16th to endNight
2217%42%32%2
376
August1st to 15thNight
412%35%40%6%
429
16th to endNight
1314%35%39%5%
753
September1st to 15thNight
2213%35%36%9%
720
16th to endNight
8%5%14%31%32%7%
716
October1st to 15thNight
12%6%18%33%22%6%
720
16th to endNight
13%9%13%33%22%7%
768
November1st to 15thNight
18%12%18%33%15%1
760
16th to endNight
18%17%17%23%18%5%
780
December1st to 15thNight
19%10%17%28%21%2
780
16th to endNight
21%18%18%28%13%1
832
Page generated at 2018-01-21 09:19:25. Version ac04

Copyright 2018 A. Danko


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