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 2017-04-07.

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%
15424
15%
45575
9%
15382
41%
15382
20%
32128

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
27%
543
14%
1723
8%
543
34%
543
19%
1207
April16th to endNight
35%
495
19%
1485
9%
495
45%
495
25%
983
May1st to 15thNight
37%
495
14%
1485
7%
495
44%
495
21%
1036
May16th to endNight
50%
514
16%
1504
12%
513
55%
513
30%
940
June1st to 15thNight
53%
495
16%
1320
11%
495
58%
495
32%
855
June16th to endNight
56%
495
14%
1320
11%
495
60%
495
33%
839
July1st to 15thNight
64%
465
17%
1240
14%
465
66%
465
41%
737
July16th to endNight
67%
522
17%
1358
14%
489
69%
489
38%
814
August1st to 15thNight
67%
494
21%
1474
18%
491
69%
491
36%
861
August16th to endNight
62%
525
21%
1610
17%
525
66%
525
33%
939
September1st to 15thNight
57%
599
26%
1754
20%
599
62%
599
34%
1051
September16th to endNight
56%
657
22%
1815
16%
657
60%
657
33%
1120
October1st to 15thNight
45%
660
20%
1886
15%
660
50%
660
26%
1241
October16th to endNight
27%
704
14%
2225
8%
704
36%
704
16%
1583
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%6%345%5%7%32%
45650
Night
15%9%46%5%34446%34%
45751
Cloud CoverDay
14%9%47%6%345%5%7%32%
45660
Night
15%9%46%5%34446%34%
45755
TransparencyDay
50%5%11%19%10%1
45344
Night
50%5%11%20%11%1
45575
SeeingDay
18%7%25%24%16%7%
5175
Night
19%8%28%29%12%1
15428

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%34446%29%
2050
16th to endDay
16%7%36%42435%7%37%
2145
May1st to 15thDay
19%9%36%445%5%45%31%
2136
16th to endDay
13%6%25%5%245%5%8%39%
2256
June1st to 15thDay
11%6%36%5%35%5%5%6%39%
2310
16th to endDay
10%5%25%6%45%7%7%9%35%
2310
July1st to 15thDay
8%5%15%4345%7%9%43%
2310
16th to endDay
8%425%6%36%6%8%9%38%
2400
August1st to 15thDay
10%5%25%6%35%6%6%9%37%
2145
16th to endDay
11%5%25%435%6%6%7%40%
2239
September1st to 15thDay
12%5%35%4336%5%7%41%
1865
16th to endDay
12%5%25%4346%6%9%39%
1815
October1st to 15thDay
14%8%36%5%24445%38%
1744
16th to endDay
21%9%35%6%34436%31%
1647
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%9%35%5%2445%6%33%
1723
16th to endNight
16%7%34424447%40%
1485
May1st to 15thNight
18%6%25%5%35%45%6%34%
1485
16th to endNight
13%4245%3445%7%46%
1502
June1st to 15thNight
11%5%15%43445%8%44%
1320
16th to endNight
9%435%5%345%6%11%42%
1320
July1st to 15thNight
8%3244235%5%9%52%
1320
16th to endNight
6%424425%35%9%50%
1459
August1st to 15thNight
7%324435%5%5%8%49%
1485
16th to endNight
10%5%24324337%51%
1610
September1st to 15thNight
12%424323445%51%
1754
16th to endNight
11%5%3442445%7%46%
1815
October1st to 15thNight
15%6%25%43445%5%41%
1886
16th to endNight
22%8%36%5%34445%32%
2225
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
20%11%46%5%34345%29%
2050
16th to endDay
16%7%36%5%2445%6%37%
2145
May1st to 15thDay
20%8%36%435%446%31%
2136
16th to endDay
13%5%35%5%345%5%8%40%
2256
June1st to 15thDay
11%6%36%6%35%6%5%7%39%
2310
16th to endDay
10%5%26%7%35%7%7%9%35%
2310
July1st to 15thDay
8%5%15%5%345%7%8%43%
2310
16th to endDay
8%415%6%46%6%9%9%38%
2400
August1st to 15thDay
10%5%35%5%36%5%5%9%38%
2145
16th to endDay
11%5%245%445%6%8%41%
2239
September1st to 15thDay
12%6%25%4345%5%8%40%
1865
16th to endDay
13%6%244346%6%9%39%
1815
October1st to 15thDay
15%7%36%6%24445%38%
1744
16th to endDay
21%9%36%6%23446%31%
1647
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
19%9%345%2445%5%33%
1723
16th to endNight
17%7%35%324447%40%
1485
May1st to 15thNight
19%6%35%6%2445%7%34%
1484
16th to endNight
12%424434347%45%
1502
June1st to 15thNight
11%6%2443445%8%44%
1320
16th to endNight
8%4345%345%6%11%42%
1320
July1st to 15thNight
8%31442445%8%53%
1320
16th to endNight
6%5%2443445%9%50%
1459
August1st to 15thNight
6%324435%5%5%9%48%
1485
16th to endNight
10%5%25%323346%51%
1610
September1st to 15thNight
13%423323445%51%
1754
16th to endNight
10%5%25%424447%46%
1815
October1st to 15thNight
15%5%35%434446%41%
1886
16th to endNight
21%8%36%5%3444432%
2225
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
56%48%19%10%
2050
16th to endDay
45%413%17%14%2
2145
May1st to 15thDay
52%5%11%19%9%1
2136
16th to endDay
42%5%13%24%12%1
2260
June1st to 15thDay
41%7%11%23%14%1
2310
16th to endDay
41%8%12%20%16%
2310
July1st to 15thDay
35%7%10%24%19%2
2161
16th to endDay
37%8%14%22%14%2
2238
August1st to 15thDay
41%7%12%23%13%2
2132
16th to endDay
38%7%11%24%16%2
2239
September1st to 15thDay
40%6%12%25%14%1
1865
16th to endDay
40%5%11%29%12%
1815
October1st to 15thDay
46%5%11%22%13%1
1744
16th to endDay
54%413%20%6%
1647
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%410%18%14%
1723
16th to endNight
43%5%11%18%17%3
1485
May1st to 15thNight
48%5%11%21%10%2
1485
16th to endNight
37%5%12%24%15%4
1504
June1st to 15thNight
38%5%12%27%15%1
1320
16th to endNight
35%6%15%24%17%
1320
July1st to 15thNight
29%5%10%29%21%2
1240
16th to endNight
30%5%16%24%20%2
1358
August1st to 15thNight
31%5%13%30%16%2
1474
16th to endNight
33%411%29%17%3
1610
September1st to 15thNight
33%5%10%29%20%1
1754
16th to endNight
36%412%27%18%
1815
October1st to 15thNight
42%5%10%22%17%1
1886
16th to endNight
53%412%21%7%
2225
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
25%9%29%24%8%2
235
16th to endDay
20%7%29%21%14%7%
210
May1st to 15thDay
27%7%25%21%13%4
228
16th to endDay
17%6%20%28%19%8%
300
June1st to 15thDay
15%6%28%30%15%4
420
16th to endDay
10%7%28%27%19%6%
420
July1st to 15thDay
12%5%20%28%21%11%
400
16th to endDay
8%422%34%20%10%
386
August1st to 15thDay
11%15%28%21%22%
253
16th to endDay
16%117%17%28%19%
268
September1st to 15thDay
13%416%21%26%17%
255
16th to endDay
17%414%22%28%12%
254
October1st to 15thDay
18%6%23%28%17%5%
255
16th to endDay
32%8%28%22%8%
159
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
23%12%32%24%6%
543
16th to endNight
22%6%32%28%8%1
495
May1st to 15thNight
21%330%33%8%1
495
16th to endNight
14%323%38%18%2
515
June1st to 15thNight
12%224%44%15%
495
16th to endNight
9%221%44%20%1
495
July1st to 15thNight
9%117%41%27%2
465
16th to endNight
6%216%47%22%4
522
August1st to 15thNight
9%114%44%25%4
494
16th to endNight
12%413%34%30%5%
525
September1st to 15thNight
15%318%31%27%4
599
16th to endNight
12%6%16%31%28%4
657
October1st to 15thNight
16%6%25%32%16%1
660
16th to endNight
25%11%31%25%6%
704
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 2017-04-08 05:35:13. Version ac04

Copyright 2017 A. Danko


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