Cohoctah Nightcrawler Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cohoctah Nightcrawler Observatory clear sky chart from 2005-11-05 to 2017-10-31.

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
36%
16095
15%
47521
10%
16053
42%
16053
20%
33304

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
17%
900
9%
2506
3%
895
21%
895
11%
2031
January16th to endNight
20%
889
8%
2617
3%
889
25%
889
11%
2095
February1st to 15thNight
17%
701
9%
2247
3%
701
23%
701
10%
1753
February16th to endNight
23%
631
14%
1893
6%
631
31%
631
13%
1441
March1st to 15thNight
28%
720
15%
2091
9%
720
33%
720
18%
1518
March16th to endNight
31%
768
18%
2112
10%
768
38%
768
21%
1495
April1st to 15thNight
28%
567
13%
1801
8%
567
34%
567
19%
1253
April16th to endNight
34%
540
20%
1620
9%
540
44%
540
25%
1069
May1st to 15thNight
36%
540
14%
1620
6%
540
43%
540
22%
1127
May16th to endNight
48%
562
16%
1645
12%
561
53%
561
29%
1047
June1st to 15thNight
56%
540
15%
1440
11%
540
60%
540
34%
913
June16th to endNight
55%
540
16%
1440
12%
540
60%
540
35%
902
July1st to 15thNight
63%
510
16%
1360
13%
510
66%
510
41%
808
July16th to endNight
67%
564
20%
1475
16%
531
70%
531
39%
872
August1st to 15thNight
67%
539
21%
1609
17%
536
69%
536
36%
938
August16th to endNight
62%
573
23%
1757
18%
573
66%
573
33%
1023
September1st to 15thNight
58%
654
25%
1914
19%
654
63%
654
35%
1134
September16th to endNight
57%
717
24%
1980
18%
717
61%
717
34%
1211
October1st to 15thNight
44%
720
19%
2058
14%
720
49%
720
25%
1374
October16th to endNight
28%
768
16%
2426
9%
768
37%
768
16%
1711
November1st to 15thNight
34%
700
19%
2276
16%
700
40%
700
21%
1494
November16th to endNight
24%
720
13%
2350
9%
720
30%
720
14%
1752
December1st to 15thNight
17%
772
7%
2572
3%
772
22%
772
9%
2032
December16th to endNight
13%
960
7%
2712
2%
960
19%
960
8%
2311

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
14%9%47%5%345%5%7%33%
48220
Night
15%9%46%5%34446%35%
47697
Cloud CoverDay
14%9%47%6%345%5%7%33%
48230
Night
15%9%46%5%34446%35%
47701
TransparencyDay
49%5%11%20%11%1
47914
Night
49%5%11%20%11%1
47521
SeeingDay
17%7%26%24%16%7%
6044
Night
19%8%28%29%12%1
16099

By Month

Percentage Cloud Cover NE (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
17%16%7%11%7%5%5%5%4416%
1432
16th to endDay
15%18%9%11%8%5%433414%
1605
February1st to 15thDay
14%15%6%10%8%5%5%446%18%
1612
16th to endDay
13%15%6%12%7%35%445%20%
1580
March1st to 15thDay
15%11%5%8%7%34447%27%
1858
16th to endDay
17%11%5%7%6%24346%30%
2112
April1st to 15thDay
20%10%46%5%34346%30%
2157
16th to endDay
15%7%36%5%25%45%7%37%
2340
May1st to 15thDay
19%8%36%445%5%46%33%
2331
16th to endDay
13%6%25%5%245%5%8%38%
2467
June1st to 15thDay
10%6%26%5%35%5%5%7%41%
2520
16th to endDay
10%5%25%6%45%7%7%9%35%
2520
July1st to 15thDay
7%5%25%435%5%7%9%44%
2520
16th to endDay
7%425%6%36%6%8%9%39%
2590
August1st to 15thDay
10%5%25%6%36%6%6%9%37%
2340
16th to endDay
11%6%25%435%6%6%7%40%
2444
September1st to 15thDay
11%5%25%4346%5%7%41%
2034
16th to endDay
12%6%25%4246%6%9%41%
1980
October1st to 15thDay
15%8%36%5%24445%38%
1902
16th to endDay
20%10%35%6%34436%31%
1797
November1st to 15thDay
15%9%35%5%34447%36%
1582
16th to endDay
16%13%6%8%5%34346%26%
1605
December1st to 15thDay
16%14%8%11%6%35%33420%
1386
16th to endDay
20%19%8%9%7%3334416%
1506
January1st to 15thNight
22%13%5%9%7%3434421%
2506
16th to endNight
13%13%7%11%7%45%5%46%19%
2617
February1st to 15thNight
16%14%5%8%7%4434425%
2245
16th to endNight
15%12%49%8%45%446%25%
1893
March1st to 15thNight
15%11%47%5%2435%5%32%
2079
16th to endNight
15%8%46%5%35%45%7%35%
2112
April1st to 15thNight
19%8%35%5%2445%6%33%
1801
16th to endNight
16%6%3442445%8%39%
1620
May1st to 15thNight
18%6%25%5%35%45%6%35%
1620
16th to endNight
12%4246%3445%7%44%
1643
June1st to 15thNight
10%5%14435%45%8%45%
1440
16th to endNight
8%435%43445%10%44%
1440
July1st to 15thNight
7%32442345%9%52%
1440
16th to endNight
6%41442435%10%50%
1576
August1st to 15thNight
7%314435%5%6%8%49%
1620
16th to endNight
9%5%25%324337%51%
1757
September1st to 15thNight
11%423323445%52%
1914
16th to endNight
10%43442445%7%47%
1980
October1st to 15thNight
16%7%25%43445%5%40%
2058
16th to endNight
21%8%36%433445%33%
2426
November1st to 15thNight
15%8%26%4345%5%6%38%
2276
16th to endNight
20%12%46%5%3445%5%27%
2350
December1st to 15thNight
19%15%7%8%6%3444421%
2572
16th to endNight
20%16%8%10%6%34445%14%
2712

Percentage Cloud Cover SE (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
16%16%7%12%6%5%46%3416%
1432
16th to endDay
15%18%9%11%9%35%32414%
1605
February1st to 15thDay
14%14%7%10%8%45%5%45%18%
1612
16th to endDay
13%15%7%12%7%35%5%45%20%
1580
March1st to 15thDay
16%11%5%8%7%34446%27%
1869
16th to endDay
17%12%48%5%33346%29%
2111
April1st to 15thDay
19%11%46%5%34346%31%
2157
16th to endDay
15%7%36%5%2445%7%37%
2340
May1st to 15thDay
20%7%35%435%446%32%
2331
16th to endDay
13%6%35%5%345%5%8%39%
2467
June1st to 15thDay
10%5%26%5%35%5%5%7%41%
2520
16th to endDay
10%5%26%7%35%7%7%9%35%
2520
July1st to 15thDay
8%5%25%5%35%5%7%8%44%
2520
16th to endDay
7%5%15%6%36%6%9%8%38%
2590
August1st to 15thDay
10%5%36%5%36%5%5%9%38%
2340
16th to endDay
11%5%25%5%445%6%7%40%
2444
September1st to 15thDay
11%5%25%5%345%5%7%41%
2034
16th to endDay
12%6%244346%6%8%41%
1980
October1st to 15thDay
15%7%36%6%23445%38%
1902
16th to endDay
21%9%36%6%23446%31%
1797
November1st to 15thDay
15%9%35%5%23447%36%
1582
16th to endDay
17%14%5%8%5%34346%26%
1605
December1st to 15thDay
16%14%8%12%6%34435%20%
1386
16th to endDay
20%18%9%9%7%3334416%
1506
January1st to 15thNight
22%13%5%9%7%3434421%
2506
16th to endNight
13%13%7%11%7%46%5%46%19%
2617
February1st to 15thNight
15%14%6%8%7%45%34425%
2238
16th to endNight
15%12%49%8%35%445%25%
1893
March1st to 15thNight
16%11%48%5%24346%32%
2091
16th to endNight
15%8%46%5%35%45%6%35%
2112
April1st to 15thNight
18%9%35%5%2446%5%33%
1801
16th to endNight
16%6%25%4245%48%39%
1620
May1st to 15thNight
19%6%35%5%2445%6%35%
1619
16th to endNight
12%4245%34447%44%
1643
June1st to 15thNight
10%5%2443445%8%46%
1440
16th to endNight
8%5%344245%5%11%43%
1440
July1st to 15thNight
7%31442445%8%52%
1440
16th to endNight
6%42342436%9%51%
1576
August1st to 15thNight
6%324435%45%9%48%
1620
16th to endNight
9%5%25%423347%51%
1757
September1st to 15thNight
12%424323445%52%
1914
16th to endNight
10%5%25%424447%47%
1980
October1st to 15thNight
16%6%35%434446%40%
2058
16th to endNight
21%9%35%5%24445%33%
2426
November1st to 15thNight
15%8%35%4345%5%6%38%
2276
16th to endNight
21%12%46%5%3445%5%27%
2350
December1st to 15thNight
19%15%6%8%5%3443422%
2572
16th to endNight
20%16%8%10%6%44345%15%
2712

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
69%6%8%11%3
1433
16th to endDay
73%47%9%4
1605
February1st to 15thDay
66%7%7%13%5%
1614
16th to endDay
65%38%14%5%1
1580
March1st to 15thDay
57%5%12%16%8%
1869
16th to endDay
55%410%19%8%
2112
April1st to 15thDay
55%49%19%10%
2157
16th to endDay
45%5%14%17%15%2
2340
May1st to 15thDay
51%5%10%19%9%2
2331
16th to endDay
42%5%13%24%12%1
2471
June1st to 15thDay
39%7%11%25%15%1
2520
16th to endDay
41%8%12%20%15%
2520
July1st to 15thDay
35%6%10%25%19%2
2371
16th to endDay
36%8%13%22%15%2
2428
August1st to 15thDay
41%6%12%24%12%2
2327
16th to endDay
39%6%10%24%16%1
2444
September1st to 15thDay
39%6%12%26%14%1
2034
16th to endDay
39%5%11%29%13%
1980
October1st to 15thDay
46%410%22%12%1
1902
16th to endDay
54%413%20%6%
1797
November1st to 15thDay
47%411%23%11%1
1582
16th to endDay
58%5%12%16%6%
1605
December1st to 15thDay
66%410%14%3
1386
16th to endDay
71%411%8%3
1506
January1st to 15thNight
65%410%12%6%
2506
16th to endNight
64%413%11%4
2617
February1st to 15thNight
62%5%9%14%6%
2247
16th to endNight
59%5%10%17%7%
1893
March1st to 15thNight
52%5%10%19%10%1
2091
16th to endNight
49%5%11%22%10%1
2112
April1st to 15thNight
50%411%18%14%
1801
16th to endNight
42%5%11%19%17%3
1620
May1st to 15thNight
48%5%10%21%10%3
1620
16th to endNight
38%5%12%24%15%3
1645
June1st to 15thNight
36%5%11%29%15%1
1440
16th to endNight
34%6%15%26%17%
1440
July1st to 15thNight
29%5%10%30%20%2
1360
16th to endNight
29%5%15%24%22%2
1475
August1st to 15thNight
31%5%13%32%15%2
1609
16th to endNight
33%411%29%18%3
1757
September1st to 15thNight
32%5%9%30%20%1
1914
16th to endNight
35%412%29%18%
1980
October1st to 15thNight
43%5%10%22%16%1
2058
16th to endNight
52%411%21%8%
2426
November1st to 15thNight
45%5%11%23%12%1
2276
16th to endNight
57%5%11%18%6%
2350
December1st to 15thNight
65%311%12%5%
2572
16th to endNight
71%5%9%9%3
2712

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
18%15%42%18%4
90
16th to endDay
34%8%35%15%5%1
96
February1st to 15thDay
25%23%40%10%1
90
16th to endDay
22%14%38%17%7%
81
March1st to 15thDay
27%11%32%23%5%
159
16th to endDay
23%6%33%23%9%1
288
April1st to 15thDay
22%10%32%24%7%2
270
16th to endDay
19%10%31%20%12%5%
270
May1st to 15thDay
27%9%24%22%12%4
288
16th to endDay
17%7%23%26%16%7%
367
June1st to 15thDay
13%6%29%30%15%4
495
16th to endDay
10%8%32%25%17%5%
495
July1st to 15thDay
11%5%22%29%21%10%
475
16th to endDay
8%5%21%33%21%10%
450
August1st to 15thDay
11%115%27%22%21%
313
16th to endDay
17%118%18%27%16%
332
September1st to 15thDay
12%5%17%20%26%18%
315
16th to endDay
15%414%21%29%14%
314
October1st to 15thDay
19%6%25%27%16%5%
315
16th to endDay
30%7%27%25%7%
213
November1st to 15thDay
14%13%24%31%14%2
90
16th to endDay
28%16%36%13%4
87
December1st to 15thDay
16%21%36%25%
60
16th to endDay
31%26%35%6%
91
January1st to 15thNight
27%13%33%19%5%
900
16th to endNight
20%11%34%27%5%
889
February1st to 15thNight
23%12%37%23%3
704
16th to endNight
21%13%32%27%5%
631
March1st to 15thNight
23%10%32%26%6%
720
16th to endNight
17%10%34%27%8%1
768
April1st to 15thNight
22%11%33%25%6%
567
16th to endNight
20%6%35%27%8%1
540
May1st to 15thNight
22%330%33%8%1
540
16th to endNight
14%325%37%16%1
563
June1st to 15thNight
11%223%46%16%
540
16th to endNight
10%223%43%19%1
540
July1st to 15thNight
9%117%41%27%2
510
16th to endNight
6%216%47%23%3
564
August1st to 15thNight
9%114%44%25%4
539
16th to endNight
11%314%34%29%5%
573
September1st to 15thNight
14%218%31%27%5%
654
16th to endNight
11%5%17%31%28%5%
717
October1st to 15thNight
18%6%24%32%16%1
720
16th to endNight
25%10%31%25%6%
768
November1st to 15thNight
20%9%30%25%11%1
700
16th to endNight
25%12%30%24%7%
720
December1st to 15thNight
27%12%34%20%3
772
16th to endNight
28%11%36%19%3
960
Page generated at 2017-11-01 17:23:36. Version ac04

Copyright 2017 A. Danko


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