Coinjock
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coinjock clear sky chart from 2005-11-05 to 2018-03-21.

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
48%
16257
21%
49226
14%
16220
55%
16220
27%
31062

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
32%
776
21%
2590
11%
776
45%
776
20%
1654
January16th to endNight
30%
832
23%
2704
12%
832
45%
832
24%
1694
February1st to 15thNight
30%
762
20%
2414
12%
761
42%
761
25%
1508
February16th to endNight
33%
683
27%
2049
15%
683
48%
683
30%
1239
March1st to 15thNight
37%
780
22%
2213
14%
780
47%
780
30%
1387
March16th to endNight
40%
792
20%
2122
13%
792
46%
792
26%
1439
April1st to 15thNight
44%
718
20%
1796
8%
718
50%
718
34%
1163
April16th to endNight
50%
720
20%
1800
9%
720
52%
720
33%
1183
May1st to 15thNight
53%
713
15%
1793
8%
713
55%
713
31%
1196
May16th to endNight
67%
374
18%
1497
21%
374
69%
374
26%
846
June1st to 15thNight
65%
360
15%
1440
18%
360
66%
360
23%
847
June16th to endNight
75%
360
17%
1440
22%
360
76%
360
24%
822
July1st to 15thNight
73%
356
13%
1376
15%
356
74%
356
26%
806
July16th to endNight
74%
564
15%
1595
13%
531
76%
531
30%
1000
August1st to 15thNight
67%
626
14%
1696
10%
623
67%
623
27%
1134
August16th to endNight
66%
764
18%
1910
11%
764
66%
764
30%
1316
September1st to 15thNight
62%
720
22%
1800
16%
720
63%
720
30%
1236
September16th to endNight
57%
717
19%
1940
16%
717
58%
717
24%
1338
October1st to 15thNight
54%
720
24%
2160
23%
720
60%
720
28%
1366
October16th to endNight
48%
768
32%
2304
25%
768
59%
768
33%
1350
November1st to 15thNight
43%
760
19%
2416
14%
760
52%
760
24%
1547
November16th to endNight
44%
780
25%
2535
19%
780
54%
780
27%
1496
December1st to 15thNight
38%
780
19%
2724
11%
780
50%
780
21%
1702
December16th to endNight
35%
832
22%
2912
14%
832
47%
832
23%
1793

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
12%5%244345%5%8%42%
49606
Night
13%5%2442445%7%43%
49411
Cloud CoverDay
12%5%244345%5%8%42%
49616
Night
13%5%2442445%7%43%
49415
TransparencyDay
38%5%14%23%15%2
49309
Night
39%5%12%22%16%3
49226
SeeingDay
16%317%28%26%8%
6510
Night
16%421%32%21%3
16264

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
16%6%24424447%42%
1676
16th to endDay
16%5%24325%45%5%44%
1872
February1st to 15thDay
15%7%25%5%2345%5%42%
1777
16th to endDay
14%5%24424448%44%
1710
March1st to 15thDay
14%423433336%49%
2062
16th to endDay
17%5%24424446%43%
2228
April1st to 15thDay
11%6%25%323346%49%
2152
16th to endDay
10%5%245%35%348%47%
2160
May1st to 15thDay
12%5%35%42445%6%42%
2167
16th to endDay
11%414325%6%6%9%42%
2618
June1st to 15thDay
9%4244245%7%11%42%
2520
16th to endDay
6%325%5%36%6%7%12%39%
2520
July1st to 15thDay
7%4145%46%6%8%10%38%
2501
16th to endDay
7%4145%37%8%8%11%37%
2465
August1st to 15thDay
10%5%25%5%35%6%6%10%36%
2238
16th to endDay
10%5%26%5%36%6%7%9%37%
2292
September1st to 15thDay
12%435%5%346%6%8%39%
2160
16th to endDay
18%8%35%5%345%5%7%32%
2016
October1st to 15thDay
16%6%25%423445%43%
1800
16th to endDay
11%5%1442335%5%51%
1920
November1st to 15thDay
18%7%2442335%6%42%
1770
16th to endDay
13%423323437%50%
1755
December1st to 15thDay
16%5%25%424446%42%
1563
16th to endDay
18%6%24424345%41%
1664
January1st to 15thNight
14%6%25%5%2445%7%41%
2590
16th to endNight
16%6%25%5%14445%43%
2704
February1st to 15thNight
18%6%24323346%43%
2413
16th to endNight
12%5%24334446%48%
2049
March1st to 15thNight
15%42442335%6%48%
2201
16th to endNight
17%5%25%5%34445%42%
2122
April1st to 15thNight
10%6%25%425%45%7%45%
1796
16th to endNight
15%6%245%23336%46%
1800
May1st to 15thNight
12%5%245%35%5%6%8%40%
1793
16th to endNight
10%5%3332445%10%45%
1495
June1st to 15thNight
9%425%5%36%5%5%10%41%
1440
16th to endNight
5%325%5%36%6%7%10%42%
1440
July1st to 15thNight
7%325%4447%8%12%38%
1457
16th to endNight
9%414436%7%7%11%40%
1703
August1st to 15thNight
9%6%26%5%35%5%6%9%37%
1707
16th to endNight
11%5%36%5%35%5%5%10%36%
1910
September1st to 15thNight
13%5%25%6%3445%8%39%
1800
16th to endNight
17%7%25%5%345%47%37%
1940
October1st to 15thNight
16%5%15%424435%46%
2160
16th to endNight
12%414323346%53%
2304
November1st to 15thNight
18%6%24423347%41%
2416
16th to endNight
15%423424446%47%
2535
December1st to 15thNight
14%6%25%5%3445%6%40%
2724
16th to endNight
16%7%35%42335%6%42%
2912

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%6%24434447%41%
1676
16th to endDay
16%5%23435%45%6%43%
1872
February1st to 15thDay
14%7%26%5%23446%41%
1777
16th to endDay
13%5%34434447%45%
1710
March1st to 15thDay
13%424434235%49%
2073
16th to endDay
17%5%25%323446%43%
2227
April1st to 15thDay
11%5%24423346%50%
2152
16th to endDay
10%5%24434438%48%
2160
May1st to 15thDay
11%5%25%5%26%45%7%42%
2167
16th to endDay
11%424425%6%6%9%43%
2618
June1st to 15thDay
9%4243245%7%11%43%
2520
16th to endDay
6%425%5%35%7%7%12%39%
2520
July1st to 15thDay
7%4246%36%6%7%11%38%
2501
16th to endDay
7%3245%36%8%7%11%38%
2465
August1st to 15thDay
10%5%26%5%36%6%6%10%36%
2238
16th to endDay
10%425%6%45%5%7%10%36%
2292
September1st to 15thDay
11%5%25%5%35%6%5%7%40%
2160
16th to endDay
19%7%26%5%345%47%32%
2016
October1st to 15thDay
17%5%25%5%23335%44%
1800
16th to endDay
11%5%245%23445%51%
1920
November1st to 15thDay
18%6%2442435%5%41%
1770
16th to endDay
12%43332335%7%50%
1755
December1st to 15thDay
16%6%24435%35%6%42%
1563
16th to endDay
18%5%25%424345%41%
1664
January1st to 15thNight
14%5%25%5%25%45%7%40%
2590
16th to endNight
16%6%25%423445%43%
2704
February1st to 15thNight
18%6%2342335%7%42%
2406
16th to endNight
12%5%2432445%6%47%
2049
March1st to 15thNight
15%5%24424346%47%
2213
16th to endNight
16%6%25%434445%42%
2122
April1st to 15thNight
11%5%25%5%3435%6%45%
1796
16th to endNight
15%6%25%424246%46%
1800
May1st to 15thNight
11%5%345%345%7%8%40%
1792
16th to endNight
10%6%2332445%10%45%
1495
June1st to 15thNight
10%325%5%35%46%9%42%
1440
16th to endNight
6%5%145%45%6%7%11%42%
1440
July1st to 15thNight
6%3245%35%7%8%12%39%
1457
16th to endNight
8%3245%36%7%7%11%40%
1703
August1st to 15thNight
9%6%35%5%36%47%10%37%
1707
16th to endNight
11%6%35%5%346%5%9%37%
1910
September1st to 15thNight
14%5%25%5%3445%8%40%
1800
16th to endNight
18%6%25%43445%7%37%
1940
October1st to 15thNight
16%6%25%423436%46%
2160
16th to endNight
12%5%23323346%52%
2304
November1st to 15thNight
17%6%2442335%7%42%
2416
16th to endNight
14%5%24323447%47%
2535
December1st to 15thNight
14%7%25%435%5%5%6%40%
2724
16th to endNight
16%7%25%5%23346%42%
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
41%5%11%19%18%3
1677
16th to endDay
41%49%24%17%4
1872
February1st to 15thDay
43%39%22%16%4
1780
16th to endDay
39%411%24%16%3
1710
March1st to 15thDay
37%312%23%18%4
2073
16th to endDay
41%312%21%17%3
2228
April1st to 15thDay
35%410%26%19%4
2152
16th to endDay
34%415%21%18%5%
2160
May1st to 15thDay
38%6%15%23%13%1
2167
16th to endDay
34%6%17%26%13%1
2622
June1st to 15thDay
32%6%19%27%12%
2520
16th to endDay
34%8%18%24%12%1
2520
July1st to 15thDay
34%8%20%25%10%
2353
16th to endDay
32%8%19%25%13%
2310
August1st to 15thDay
40%7%18%21%11%
2225
16th to endDay
38%6%19%22%9%2
2292
September1st to 15thDay
38%7%15%20%14%2
2160
16th to endDay
49%5%10%19%14%
2016
October1st to 15thDay
42%38%24%19%2
1800
16th to endDay
34%45%26%24%4
1920
November1st to 15thDay
43%312%19%17%4
1770
16th to endDay
33%311%25%20%4
1755
December1st to 15thDay
43%312%23%14%2
1563
16th to endDay
45%310%23%13%3
1664
January1st to 15thNight
43%5%8%21%17%4
2590
16th to endNight
42%39%22%16%5%
2704
February1st to 15thNight
42%28%23%19%3
2414
16th to endNight
36%410%26%18%5%
2049
March1st to 15thNight
38%411%24%17%4
2213
16th to endNight
43%48%22%16%3
2122
April1st to 15thNight
38%313%19%20%4
1796
16th to endNight
40%29%22%19%5%
1800
May1st to 15thNight
39%5%17%24%11%1
1793
16th to endNight
34%7%17%25%12%2
1497
June1st to 15thNight
37%7%17%26%10%
1440
16th to endNight
33%9%18%24%12%1
1440
July1st to 15thNight
33%10%23%20%12%1
1376
16th to endNight
33%9%18%25%11%1
1595
August1st to 15thNight
41%7%18%21%11%
1696
16th to endNight
41%7%16%24%9%1
1910
September1st to 15thNight
41%6%15%19%14%2
1800
16th to endNight
46%5%11%19%16%
1940
October1st to 15thNight
40%49%22%20%3
2160
16th to endNight
33%46%24%25%4
2304
November1st to 15thNight
42%5%9%17%20%4
2416
16th to endNight
37%38%24%19%5%
2535
December1st to 15thNight
43%412%20%15%3
2724
16th to endNight
43%312%21%14%4
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
19%7%35%30%7%
119
16th to endDay
18%6%31%29%11%3
144
February1st to 15thDay
24%9%32%28%5%
203
16th to endDay
15%5%34%32%12%
291
March1st to 15thDay
15%7%37%25%12%
330
16th to endDay
18%425%37%8%5%
311
April1st to 15thDay
15%5%26%31%18%2
270
16th to endDay
11%221%32%27%5%
270
May1st to 15thDay
18%320%37%17%3
288
16th to endDay
15%11%24%31%16%
331
June1st to 15thDay
15%17%25%33%15%
315
16th to endDay
10%6%30%43%8%
315
July1st to 15thDay
9%326%44%14%
305
16th to endDay
11%1123%43%18%
326
August1st to 15thDay
15%1226%38%15%
313
16th to endDay
11%422%43%17%
332
September1st to 15thDay
12%10%23%37%14%
315
16th to endDay
27%18%24%32%5%
314
October1st to 15thDay
26%112%26%26%6%
315
16th to endDay
10%420%27%25%10%
336
November1st to 15thDay
21%5%21%29%17%5%
293
16th to endDay
14%9%22%28%22%2
285
December1st to 15thDay
24%6%25%27%12%2
93
16th to endDay
25%128%34%11%
96
January1st to 15thNight
16%12%31%28%10%
780
16th to endNight
19%8%36%29%6%
832
February1st to 15thNight
23%6%34%32%3
764
16th to endNight
14%8%38%29%8%
683
March1st to 15thNight
17%5%34%31%10%1
780
16th to endNight
20%426%34%12%1
792
April1st to 15thNight
12%331%36%14%
718
16th to endNight
16%320%39%16%2
720
May1st to 15thNight
15%219%40%19%1
713
16th to endNight
13%27%31%35%9%
375
June1st to 15thNight
10%28%36%34%7%
360
16th to endNight
6%15%43%38%4
360
July1st to 15thNight
8%5%31%45%7%
356
16th to endNight
10%1229%43%10%
564
August1st to 15thNight
13%2233%38%9%
626
16th to endNight
14%1327%42%11%
764
September1st to 15thNight
17%25%26%39%8%
720
16th to endNight
22%18%32%31%4
717
October1st to 15thNight
20%213%29%28%6%
720
16th to endNight
15%6%23%29%19%5%
768
November1st to 15thNight
19%5%21%33%15%4
760
16th to endNight
16%7%25%30%18%1
780
December1st to 15thNight
17%7%30%29%14%
780
16th to endNight
18%6%33%34%6%
832
Page generated at 2018-03-22 11:34:23. Version ac04

Copyright 2018 A. Danko


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