Crestview
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Crestview clear sky chart from 2005-11-05 to 2018-02-14.

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
62%
15931
32%
48782
25%
15904
70%
15904
51%
22785

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
58%
776
28%
2716
22%
776
70%
776
44%
1246
January16th to endNight
58%
832
29%
2740
26%
832
65%
832
41%
1352
February1st to 15thNight
56%
755
31%
2328
26%
755
64%
755
45%
1152
February16th to endNight
51%
632
28%
1895
23%
632
61%
632
40%
992
March1st to 15thNight
50%
720
27%
2160
20%
720
61%
720
43%
1066
March16th to endNight
46%
768
26%
1989
14%
768
55%
768
45%
1087
April1st to 15thNight
47%
719
25%
1799
10%
719
55%
719
41%
1041
April16th to endNight
51%
720
24%
1800
10%
720
57%
720
51%
963
May1st to 15thNight
56%
578
28%
1658
18%
578
62%
578
52%
801
May16th to endNight
58%
436
27%
1559
23%
436
65%
436
42%
713
June1st to 15thNight
66%
360
29%
1440
29%
360
76%
360
49%
564
June16th to endNight
77%
360
37%
1440
41%
360
86%
360
70%
455
July1st to 15thNight
88%
340
33%
1360
43%
340
89%
340
65%
460
July16th to endNight
80%
409
37%
1447
41%
385
82%
385
53%
586
August1st to 15thNight
81%
686
36%
1760
23%
683
83%
683
72%
817
August16th to endNight
83%
764
42%
1910
26%
764
85%
764
74%
901
September1st to 15thNight
81%
720
42%
1800
28%
720
85%
720
75%
832
September16th to endNight
75%
716
45%
1971
36%
716
82%
716
68%
878
October1st to 15thNight
67%
720
34%
2079
29%
720
76%
720
56%
975
October16th to endNight
70%
768
41%
2349
38%
768
80%
768
58%
1020
November1st to 15thNight
66%
760
33%
2470
31%
760
74%
760
55%
1078
November16th to endNight
57%
780
36%
2535
28%
780
71%
780
52%
1091
December1st to 15thNight
53%
780
26%
2665
19%
780
64%
780
43%
1217
December16th to endNight
47%
832
27%
2912
23%
832
58%
832
35%
1498

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
2313323347%65%
49303
Night
1212212347%70%
48959
TransparencyDay
19%49%21%26%18%
48977
Night
15%411%25%28%13%
48785
SeeingDay
6%18%30%26%13%4
6231
Night
28%23%32%26%7%
15942

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
1133225%411%62%
1552
16th to endDay
13233245%6%8%57%
1834
February1st to 15thDay
2233233410%62%
1832
16th to endDay
3244235%6%8%57%
1579
March1st to 15thDay
22322346%13%58%
1800
16th to endDay
3123245%7%9%57%
2230
April1st to 15thDay
232432346%8%58%
2149
16th to endDay
1422213346%65%
2160
May1st to 15thDay
241232345%6%63%
2292
16th to endDay
47%25%424436%54%
2551
June1st to 15thDay
5%212224346%64%
2520
16th to endDay
22121222378%
2520
July1st to 15thDay
3213313336%66%
2520
16th to endDay
5%31332333464%
2622
August1st to 15thDay
22132333373%
2190
16th to endDay
221221233473%
2292
September1st to 15thDay
321321233470%
2160
16th to endDay
1212212235%75%
1989
October1st to 15thDay
2312311235%71%
1878
16th to endDay
1213211236%73%
1873
November1st to 15thDay
121221135%9%68%
1719
16th to endDay
2111225%9%71%
1755
December1st to 15thDay
213223448%66%
1622
16th to endDay
11442447%10%57%
1664
January1st to 15thNight
21331335%9%62%
2716
16th to endNight
32221345%9%62%
2740
February1st to 15thNight
313323449%64%
2318
16th to endNight
323313348%64%
1895
March1st to 15thNight
21232346%9%64%
2160
16th to endNight
32321235%8%65%
1989
April1st to 15thNight
1323215%45%7%62%
1799
16th to endNight
1323312345%69%
1800
May1st to 15thNight
1311313237%69%
1658
16th to endNight
4413212245%67%
1559
June1st to 15thNight
21221335%6%69%
1440
16th to endNight
1111112285%
1440
July1st to 15thNight
11111233477%
1440
16th to endNight
321231333471%
1545
August1st to 15thNight
11121222380%
1769
16th to endNight
1121123480%
1910
September1st to 15thNight
11111223382%
1800
16th to endNight
12111123480%
1971
October1st to 15thNight
23121124474%
2079
16th to endNight
111112335%77%
2349
November1st to 15thNight
111112337%74%
2470
16th to endNight
22212337%72%
2535
December1st to 15thNight
12411235%8%66%
2665
16th to endNight
1144245%7%11%57%
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
18%6%15%27%24%7%
1552
16th to endDay
24%7%13%21%23%10%
1834
February1st to 15thDay
19%5%15%26%23%9%
1832
16th to endDay
25%7%11%25%26%3
1579
March1st to 15thDay
21%6%16%25%22%7%
1800
16th to endDay
22%9%19%28%16%4
2230
April1st to 15thDay
25%6%15%28%17%6%
2149
16th to endDay
21%5%15%29%21%6%
2160
May1st to 15thDay
23%5%10%32%24%4
2292
16th to endDay
31%49%23%24%6%
2555
June1st to 15thDay
22%29%20%29%15%
2520
16th to endDay
12%1210%39%32%
2520
July1st to 15thDay
19%247%23%43%
2371
16th to endDay
22%249%19%41%
2457
August1st to 15thDay
15%1211%22%45%
2174
16th to endDay
15%129%36%34%
2292
September1st to 15thDay
19%2311%30%33%
2160
16th to endDay
14%2224%33%21%
1989
October1st to 15thDay
18%25%22%32%19%
1878
16th to endDay
13%35%23%36%16%
1873
November1st to 15thDay
14%310%31%28%11%
1719
16th to endDay
12%5%13%27%34%7%
1755
December1st to 15thDay
18%7%13%28%23%8%
1622
16th to endDay
22%10%16%22%19%8%
1664
January1st to 15thNight
18%5%15%27%25%7%
2716
16th to endNight
19%8%13%23%23%11%
2740
February1st to 15thNight
20%412%29%21%10%
2329
16th to endNight
20%7%13%27%25%4
1895
March1st to 15thNight
18%6%16%26%23%8%
2160
16th to endNight
19%6%20%30%19%3
1989
April1st to 15thNight
23%5%15%31%19%4
1799
16th to endNight
18%419%32%19%5%
1800
May1st to 15thNight
17%314%34%25%4
1659
16th to endNight
20%312%31%25%5%
1560
June1st to 15thNight
15%310%26%32%10%
1440
16th to endNight
7%1415%40%30%
1440
July1st to 15thNight
9%2412%33%37%
1360
16th to endNight
16%2314%27%35%
1447
August1st to 15thNight
10%1415%26%41%
1760
16th to endNight
8%2214%42%27%
1910
September1st to 15thNight
8%2416%41%26%
1800
16th to endNight
10%2428%36%18%
1971
October1st to 15thNight
15%37%25%35%12%
2079
16th to endNight
11%47%26%36%14%
2349
November1st to 15thNight
12%6%11%27%29%12%
2470
16th to endNight
12%413%29%31%7%
2535
December1st to 15thNight
16%6%18%25%24%7%
2665
16th to endNight
22%9%13%24%22%7%
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
222%32%23%8%11%
90
16th to endDay
321%28%27%14%5%
266
February1st to 15thDay
223%25%23%19%5%
309
16th to endDay
5%23%33%23%13%
238
March1st to 15thDay
226%32%20%12%5%
270
16th to endDay
6%30%32%22%7%
288
April1st to 15thDay
8%33%28%17%8%2
269
16th to endDay
9%31%35%18%4
270
May1st to 15thDay
7%21%35%21%7%5%
288
16th to endDay
13%19%25%23%14%3
330
June1st to 15thDay
9%20%36%21%9%3
315
16th to endDay
5%15%34%28%11%5%
315
July1st to 15thDay
4333%34%17%6%
305
16th to endDay
8%7%31%35%10%6%
327
August1st to 15thDay
411%36%27%15%4
315
16th to endDay
47%30%32%15%9%
332
September1st to 15thDay
8%10%27%32%16%3
315
16th to endDay
7%11%29%31%18%2
315
October1st to 15thDay
418%34%26%12%3
315
16th to endDay
415%27%27%18%6%
289
November1st to 15thDay
317%20%16%25%16%
135
16th to endDay
121%17%37%18%3
135
December1st to 15thDay
317%32%26%12%6%
104
16th to endDay
114%26%31%16%10%
96
January1st to 15thNight
29%25%28%22%11%
780
16th to endNight
27%26%33%19%9%
832
February1st to 15thNight
19%27%30%24%6%
760
16th to endNight
215%27%31%15%6%
632
March1st to 15thNight
112%31%28%17%7%
720
16th to endNight
116%31%27%18%4
768
April1st to 15thNight
314%30%29%17%4
719
16th to endNight
311%28%29%19%7%
720
May1st to 15thNight
38%27%33%23%4
579
16th to endNight
5%8%23%29%27%6%
437
June1st to 15thNight
2323%36%31%2
360
16th to endNight
2117%44%31%3
360
July1st to 15thNight
15%46%42%3
340
16th to endNight
46%37%45%5%
409
August1st to 15thNight
2112%39%37%6%
686
16th to endNight
1110%35%41%9%
764
September1st to 15thNight
2111%33%41%9%
720
16th to endNight
2414%31%34%11%
716
October1st to 15thNight
37%19%34%25%10%
720
16th to endNight
28%16%27%30%14%
768
November1st to 15thNight
15%24%30%26%10%
760
16th to endNight
112%25%28%23%8%
780
December1st to 15thNight
210%28%33%17%7%
780
16th to endNight
13%34%28%18%3
832
Page generated at 2018-02-15 07:58:51. Version ac04

Copyright 2018 A. Danko


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