Knight Sight
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Knight Sight clear sky chart from 2005-11-05 to 2018-01-12.

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
68%
16261
38%
48181
30%
16220
76%
16220
63%
20903

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%
760
29%
2623
28%
760
74%
760
47%
1193
January16th to endNight
64%
768
39%
2332
33%
768
74%
768
52%
1107
February1st to 15thNight
65%
698
35%
2107
31%
697
73%
697
54%
994
February16th to endNight
56%
632
35%
1895
30%
632
68%
632
48%
941
March1st to 15thNight
61%
720
33%
2160
29%
720
73%
720
55%
987
March16th to endNight
54%
768
37%
2025
21%
768
67%
768
61%
966
April1st to 15thNight
47%
719
35%
1799
12%
719
61%
719
59%
897
April16th to endNight
53%
720
40%
1800
15%
720
65%
720
72%
808
May1st to 15thNight
53%
564
38%
1643
21%
563
62%
563
72%
654
May16th to endNight
49%
561
36%
1685
20%
561
61%
561
70%
651
June1st to 15thNight
57%
506
36%
1586
25%
506
67%
506
77%
576
June16th to endNight
72%
360
42%
1440
43%
360
82%
360
83%
409
July1st to 15thNight
86%
340
37%
1360
40%
340
91%
340
67%
450
July16th to endNight
81%
588
35%
1615
28%
553
82%
553
63%
725
August1st to 15thNight
83%
717
39%
1790
23%
713
85%
713
84%
781
August16th to endNight
87%
764
46%
1910
29%
764
89%
764
80%
855
September1st to 15thNight
85%
720
42%
1854
31%
720
90%
720
78%
822
September16th to endNight
83%
716
50%
1980
42%
716
90%
716
85%
781
October1st to 15thNight
71%
720
42%
1980
32%
720
82%
720
70%
861
October16th to endNight
76%
768
47%
2353
43%
768
85%
768
70%
945
November1st to 15thNight
77%
760
38%
2470
38%
760
84%
760
64%
992
November16th to endNight
75%
780
42%
2535
42%
780
82%
780
61%
1044
December1st to 15thNight
68%
780
35%
2535
32%
780
76%
780
53%
1144
December16th to endNight
62%
832
35%
2704
31%
832
71%
832
44%
1320

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
111212235%75%
49135
Night
111212235%75%
48373
TransparencyDay
12%25%15%26%36%
48822
Night
11%26%17%29%31%
48187
SeeingDay
310%21%31%24%9%
6229
Night
15%21%39%28%3
16273

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
3114323338%63%
1545
16th to endDay
4414323346%61%
1890
February1st to 15thDay
1112323347%68%
1751
16th to endDay
3213424347%62%
1579
March1st to 15thDay
11121245%9%68%
1800
16th to endDay
111121345%7%70%
2196
April1st to 15thDay
2111212237%73%
2149
16th to endDay
1111136%79%
2160
May1st to 15thDay
111125%82%
2307
16th to endDay
1111112482%
2429
June1st to 15thDay
1113484%
2370
16th to endDay
1111288%
2520
July1st to 15thDay
11121233476%
2520
16th to endDay
1112314345%71%
2436
August1st to 15thDay
111112482%
2160
16th to endDay
122222479%
2292
September1st to 15thDay
111233480%
2106
16th to endDay
1212286%
1980
October1st to 15thDay
111112335%77%
1980
16th to endDay
1111135%80%
1868
November1st to 15thDay
111112335%75%
1719
16th to endDay
212213337%70%
1755
December1st to 15thDay
221232435%10%62%
1755
16th to endDay
4314323446%61%
1868
January1st to 15thNight
3213313446%65%
2623
16th to endNight
3212223336%67%
2332
February1st to 15thNight
2212212347%68%
2101
16th to endNight
421232345%7%62%
1895
March1st to 15thNight
112313347%69%
2160
16th to endNight
11221235%8%71%
2025
April1st to 15thNight
1111112347%72%
1799
16th to endNight
1111135%82%
1800
May1st to 15thNight
112235%82%
1643
16th to endNight
111125%83%
1684
June1st to 15thNight
1122486%
1586
16th to endNight
11291%
1440
July1st to 15thNight
11111222381%
1440
16th to endNight
121221233475%
1724
August1st to 15thNight
11122385%
1800
16th to endNight
1112384%
1910
September1st to 15thNight
11112384%
1854
16th to endNight
1112289%
1980
October1st to 15thNight
1111223479%
1980
16th to endNight
11111122382%
2353
November1st to 15thNight
11212245%76%
2470
16th to endNight
22212337%73%
2535
December1st to 15thNight
2212313347%66%
2535
16th to endNight
421331335%6%63%
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
20%210%24%27%15%
1545
16th to endDay
23%47%22%23%18%
1890
February1st to 15thDay
17%27%21%28%22%
1751
16th to endDay
21%37%22%30%12%
1579
March1st to 15thDay
12%28%25%29%21%
1800
16th to endDay
12%39%25%28%19%
2196
April1st to 15thDay
13%3421%34%22%
2149
16th to endDay
8%26%20%32%29%
2160
May1st to 15thDay
8%1419%31%35%
2307
16th to endDay
8%1415%37%31%
2432
June1st to 15thDay
6%1211%23%54%
2370
16th to endDay
5%11414%72%
2520
July1st to 15thDay
10%236%17%59%
2371
16th to endDay
15%2412%21%43%
2283
August1st to 15thDay
7%127%16%64%
2146
16th to endDay
10%126%24%55%
2292
September1st to 15thDay
9%138%22%54%
2106
16th to endDay
6%116%31%52%
1980
October1st to 15thDay
10%3312%31%39%
1980
16th to endDay
8%1414%27%43%
1868
November1st to 15thDay
12%26%18%37%23%
1719
16th to endDay
13%36%19%32%24%
1755
December1st to 15thDay
16%5%11%22%25%19%
1755
16th to endDay
22%6%9%24%23%13%
1868
January1st to 15thNight
19%38%20%29%18%
2623
16th to endNight
18%28%22%23%23%
2332
February1st to 15thNight
16%38%20%26%23%
2112
16th to endNight
19%48%23%28%15%
1895
March1st to 15thNight
14%38%24%26%21%
2160
16th to endNight
12%311%26%29%16%
2025
April1st to 15thNight
13%39%27%28%17%
1799
16th to endNight
6%17%28%32%22%
1800
May1st to 15thNight
6%26%22%35%26%
1644
16th to endNight
7%17%21%41%21%
1685
June1st to 15thNight
41415%28%45%
1586
16th to endNight
316%20%65%
1440
July1st to 15thNight
8%218%19%59%
1360
16th to endNight
13%25%11%24%41%
1615
August1st to 15thNight
5%127%28%55%
1790
16th to endNight
6%118%30%50%
1910
September1st to 15thNight
7%248%30%46%
1854
16th to endNight
31110%33%49%
1980
October1st to 15thNight
9%2412%34%36%
1980
16th to endNight
8%2411%26%45%
2353
November1st to 15thNight
11%26%17%35%27%
2470
16th to endNight
12%36%20%27%30%
2535
December1st to 15thNight
16%310%18%28%21%
2535
16th to endNight
20%411%21%26%14%
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
8%12%18%32%21%6%
87
16th to endDay
6%14%19%28%20%9%
258
February1st to 15thDay
113%24%28%21%10%
266
16th to endDay
5%21%22%26%17%6%
238
March1st to 15thDay
6%13%23%28%21%7%
270
16th to endDay
417%28%24%20%4
288
April1st to 15thDay
5%23%23%24%15%7%
269
16th to endDay
325%28%22%15%4
270
May1st to 15thDay
414%26%28%20%5%
288
16th to endDay
313%31%26%19%6%
330
June1st to 15thDay
111%30%29%19%7%
315
16th to endDay
429%32%21%10%
315
July1st to 15thDay
1217%38%26%13%
305
16th to endDay
312%40%26%16%
327
August1st to 15thDay
3122%34%26%12%
315
16th to endDay
1114%36%30%15%
332
September1st to 15thDay
220%39%26%10%
315
16th to endDay
15%15%36%29%10%
315
October1st to 15thDay
29%22%33%24%6%
315
16th to endDay
26%18%25%31%15%
263
November1st to 15thDay
26%17%27%29%16%
135
16th to endDay
114%9%28%37%8%
135
December1st to 15thDay
418%35%31%9%
135
16th to endDay
5%9%13%30%34%6%
143
January1st to 15thNight
2417%41%28%4
764
16th to endNight
4421%38%27%2
768
February1st to 15thNight
3420%39%28%3
704
16th to endNight
48%28%36%18%3
632
March1st to 15thNight
18%24%39%22%2
720
16th to endNight
19%32%34%20%1
768
April1st to 15thNight
212%35%28%18%2
719
16th to endNight
11%32%33%18%2
720
May1st to 15thNight
7%37%38%15%1
564
16th to endNight
10%36%34%16%
563
June1st to 15thNight
6%35%45%12%
506
16th to endNight
26%56%15%
360
July1st to 15thNight
8%56%32%1
340
16th to endNight
210%55%31%1
588
August1st to 15thNight
112%47%34%4
717
16th to endNight
7%40%42%7%
764
September1st to 15thNight
19%36%45%6%
720
16th to endNight
212%36%41%6%
716
October1st to 15thNight
1321%37%33%2
720
16th to endNight
1216%31%38%8%
768
November1st to 15thNight
215%43%32%5%
760
16th to endNight
2314%38%35%6%
780
December1st to 15thNight
3419%40%29%4
780
16th to endNight
46%20%41%23%2
832
Page generated at 2018-01-12 19:01:30. Version ac04

Copyright 2018 A. Danko


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