Echo Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Echo Bay clear sky chart from 2005-11-06 to 2024-01-14.

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
69%
24336
37%
74411
29%
24294
77%
24294
55%
34087

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 10thNight
61%
759
32%
2457
26%
756
71%
756
43%
1198
January11th to 20thNight
69%
734
37%
2385
34%
734
77%
734
50%
1093
January21st to endNight
60%
792
36%
2574
29%
792
74%
792
41%
1267
February1st to 10thNight
62%
720
35%
2169
27%
720
74%
720
48%
1061
February11th to 20thNight
57%
700
37%
2099
30%
700
70%
700
46%
1033
February21st to endNight
54%
592
36%
1776
30%
592
65%
592
47%
855
March1st to 10thNight
58%
720
32%
2132
26%
720
69%
720
47%
1047
March11th to 20thNight
59%
720
34%
1980
26%
720
68%
720
48%
1036
March21st to endNight
56%
792
35%
2178
21%
792
68%
792
51%
1096
April1st to 10thNight
58%
720
34%
1886
19%
720
67%
720
55%
933
April11th to 20thNight
54%
711
36%
1779
15%
711
66%
711
56%
896
April21st to endNight
63%
540
44%
1620
26%
540
75%
540
61%
690
May1st to 10thNight
60%
540
37%
1620
22%
540
70%
540
59%
713
May11th to 20thNight
68%
531
40%
1595
27%
531
76%
531
68%
651
May21st to endNight
65%
582
33%
1746
23%
582
72%
582
61%
749
June1st to 10thNight
73%
540
36%
1620
27%
540
80%
540
78%
614
June11th to 20thNight
69%
540
36%
1620
29%
540
75%
540
73%
634
June21st to endNight
81%
540
34%
1620
30%
540
85%
540
77%
633
July1st to 10thNight
83%
525
33%
1575
29%
525
85%
525
69%
668
July11th to 20thNight
80%
522
30%
1566
27%
522
81%
522
56%
735
July21st to endNight
80%
591
31%
1674
26%
558
81%
558
50%
838
August1st to 10thNight
80%
537
39%
1602
30%
534
82%
534
60%
720
August11th to 20thNight
85%
606
41%
1674
29%
606
87%
606
68%
758
August21st to endNight
85%
792
41%
1980
29%
792
86%
792
72%
950
September1st to 10thNight
81%
720
40%
1921
30%
720
85%
720
68%
883
September11th to 20thNight
83%
720
45%
1980
37%
720
88%
720
76%
838
September21st to endNight
78%
720
45%
1980
34%
720
85%
720
75%
837
October1st to 10thNight
74%
720
41%
1980
32%
720
82%
720
65%
909
October11th to 20thNight
75%
720
46%
2078
37%
720
84%
720
68%
885
October21st to endNight
71%
792
45%
2438
36%
792
83%
792
66%
974
November1st to 10thNight
73%
740
40%
2405
37%
740
83%
740
64%
965
November11th to 20thNight
75%
760
42%
2470
39%
760
84%
760
62%
998
November21st to endNight
69%
760
39%
2470
36%
760
77%
760
55%
1068
December1st to 10thNight
64%
760
34%
2470
30%
760
72%
760
44%
1180
December11th to 20thNight
66%
758
33%
2907
29%
758
74%
758
36%
1463
December21st to endNight
57%
820
20%
4385
27%
817
67%
817
23%
2219

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
2212223346%72%
74914
Night
3213323346%70%
74886
TransparencyDay
14%36%15%26%35%
74641
Night
16%36%14%26%35%
74681
SeeingDay
48%19%31%28%11%
14063
Night
46%17%38%31%4
24361

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 10thDay
432442346%7%62%
1708
11th to 20thDay
3413213449%65%
1647
21st to endDay
6%323323446%63%
1782
February1st to 10thDay
3313323246%70%
1789
11th to 20thDay
321332445%6%66%
1750
21st to endDay
5%313333345%65%
1480
March1st to 10thDay
331342345%7%66%
1827
11th to 20thDay
3414324346%65%
1980
21st to endDay
23124235%6%8%64%
2178
April1st to 10thDay
2213333447%67%
2070
11th to 20thDay
3212222345%74%
2129
21st to endDay
2212223336%75%
2340
May1st to 10thDay
1112223346%77%
2340
11th to 20thDay
1111112236%80%
2301
21st to endDay
1112212336%78%
2530
June1st to 10thDay
111111233482%
2340
11th to 20thDay
121111122485%
2340
21st to endDay
1112111225%83%
2340
July1st to 10thDay
1112223446%75%
2340
11th to 20thDay
221322345%7%68%
2340
21st to endDay
3213435%5%7%9%58%
2545
August1st to 10thDay
2212222347%72%
2328
11th to 20thDay
21121335%8%74%
2223
21st to endDay
221212346%76%
2376
September1st to 10thDay
2112212345%76%
2039
11th to 20thDay
111121112386%
1980
21st to endDay
111211222481%
1980
October1st to 10thDay
2112222335%75%
1980
11th to 20thDay
111112223482%
1880
21st to endDay
111111223484%
1913
November1st to 10thDay
2211212346%76%
1674
11th to 20thDay
2212222335%77%
1710
21st to endDay
3222213446%70%
1710
December1st to 10thDay
4313423348%65%
1710
11th to 20thDay
5%424435%47%10%52%
2169
21st to endDay
6%42443447%9%55%
3146
January1st to 10thNight
5%423323347%64%
2457
11th to 20thNight
3313323348%67%
2385
21st to endNight
6%41332345%7%61%
2574
February1st to 10thNight
3324333346%68%
2169
11th to 20thNight
5%31332334467%
2098
21st to endNight
6%3133235%6%5%64%
1776
March1st to 10thNight
431332346%8%62%
2132
11th to 20thNight
442342335%6%64%
1980
21st to endNight
3314324346%67%
2178
April1st to 10thNight
2212224347%70%
1886
11th to 20thNight
2213322446%71%
1779
21st to endNight
2112213347%75%
1620
May1st to 10thNight
2212313346%73%
1620
11th to 20thNight
1212112235%80%
1594
21st to endNight
2112323346%74%
1746
June1st to 10thNight
111112236%82%
1620
11th to 20thNight
111111123483%
1620
21st to endNight
111111235%83%
1620
July1st to 10thNight
12121335%6%75%
1620
11th to 20thNight
32134245%47%65%
1620
21st to endNight
2324436%5%5%9%57%
1773
August1st to 10thNight
3212323345%72%
1611
11th to 20thNight
2111313246%75%
1674
21st to endNight
121231335%6%74%
1980
September1st to 10thNight
2212313345%75%
1921
11th to 20thNight
11221223384%
1980
21st to endNight
111221222483%
1980
October1st to 10thNight
3212212326%77%
1980
11th to 20thNight
211221222382%
2078
21st to endNight
112211245%80%
2438
November1st to 10thNight
2212212245%77%
2405
11th to 20thNight
3212111345%77%
2470
21st to endNight
4213322347%71%
2470
December1st to 10thNight
5%423313446%65%
2470
11th to 20thNight
7%41442345%8%58%
3041
21st to endNight
7%5%25%5%3445%7%52%
4521

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 10thDay
20%7%12%30%26%5%
1709
11th to 20thDay
19%5%11%27%31%8%
1647
21st to endDay
22%47%29%30%7%
1782
February1st to 10thDay
17%48%22%30%18%
1789
11th to 20thDay
18%47%20%32%19%
1760
21st to endDay
20%48%21%32%16%
1480
March1st to 10thDay
17%47%18%35%19%
1827
11th to 20thDay
20%46%16%34%20%
1980
21st to endDay
17%48%22%32%18%
2178
April1st to 10thDay
18%35%15%30%29%
2070
11th to 20thDay
14%25%13%26%40%
2132
21st to endDay
12%2412%33%36%
2340
May1st to 10thDay
11%25%12%30%40%
2340
11th to 20thDay
8%2410%31%46%
2304
21st to endDay
10%249%28%46%
2530
June1st to 10thDay
7%237%20%61%
2340
11th to 20thDay
6%125%15%71%
2340
21st to endDay
7%22412%73%
2340
July1st to 10thDay
11%346%13%62%
2276
11th to 20thDay
14%46%12%21%43%
2271
21st to endDay
19%6%10%15%19%31%
2404
August1st to 10thDay
13%36%10%19%49%
2313
11th to 20thDay
8%35%10%24%49%
2223
21st to endDay
10%25%10%24%49%
2376
September1st to 10thDay
11%45%9%17%54%
2039
11th to 20thDay
7%138%24%56%
1980
21st to endDay
9%238%24%54%
1980
October1st to 10thDay
13%3413%24%42%
1980
11th to 20thDay
9%2310%32%43%
1880
21st to endDay
7%2413%38%36%
1913
November1st to 10thDay
11%2419%38%25%
1674
11th to 20thDay
13%36%18%40%20%
1710
21st to endDay
15%37%22%36%17%
1710
December1st to 10thDay
20%411%23%29%12%
1710
11th to 20thDay
26%8%13%26%22%5%
2168
21st to endDay
24%8%14%27%21%7%
3146
January1st to 10thNight
21%5%8%28%30%8%
2457
11th to 20thNight
17%47%26%32%14%
2385
21st to endNight
23%48%23%32%10%
2574
February1st to 10thNight
20%37%17%34%19%
2169
11th to 20thNight
21%36%18%26%26%
2099
21st to endNight
19%38%14%35%20%
1776
March1st to 10thNight
19%47%17%31%22%
2132
11th to 20thNight
21%4412%31%28%
1980
21st to endNight
18%46%17%33%23%
2178
April1st to 10thNight
16%36%13%29%33%
1886
11th to 20thNight
15%25%11%30%36%
1779
21st to endNight
12%2411%28%43%
1620
May1st to 10thNight
13%25%9%26%44%
1620
11th to 20thNight
10%2410%25%50%
1595
21st to endNight
11%349%24%49%
1746
June1st to 10thNight
6%136%18%66%
1620
11th to 20thNight
7%22413%71%
1620
21st to endNight
6%2239%77%
1620
July1st to 10thNight
11%246%10%67%
1575
11th to 20thNight
17%45%10%18%47%
1566
21st to endNight
19%6%10%15%20%31%
1674
August1st to 10thNight
15%349%16%53%
1602
11th to 20thNight
11%35%8%20%53%
1674
21st to endNight
10%348%21%53%
1980
September1st to 10thNight
11%349%18%55%
1921
11th to 20thNight
7%338%19%61%
1980
21st to endNight
8%137%19%62%
1980
October1st to 10thNight
12%3411%22%48%
1980
11th to 20thNight
11%228%24%54%
2078
21st to endNight
9%2411%28%46%
2438
November1st to 10thNight
11%2414%38%30%
2405
11th to 20thNight
12%25%15%37%29%
2470
21st to endNight
15%26%14%35%27%
2470
December1st to 10thNight
21%48%21%27%19%
2470
11th to 20thNight
25%5%10%22%30%7%
3041
21st to endNight
28%9%10%22%26%6%
4521

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 10thDay
10%11%17%41%18%2
270
11th to 20thDay
10%6%18%41%21%4
249
21st to endDay
6%9%16%33%25%10%
264
February1st to 10thDay
6%10%19%32%24%10%
409
11th to 20thDay
7%14%23%31%19%7%
415
21st to endDay
7%19%22%28%21%4
346
March1st to 10thDay
7%18%24%25%19%6%
420
11th to 20thDay
9%12%22%29%20%9%
420
21st to endDay
6%15%30%29%16%4
462
April1st to 10thDay
5%14%26%30%18%7%
420
11th to 20thDay
5%17%30%26%17%4
412
21st to endDay
415%23%26%22%9%
420
May1st to 10thDay
411%32%27%21%6%
423
11th to 20thDay
29%25%33%24%7%
448
21st to endDay
29%25%28%27%9%
485
June1st to 10thDay
18%21%33%26%10%
450
11th to 20thDay
28%20%28%30%12%
450
21st to endDay
15%18%32%34%11%
450
July1st to 10thDay
1113%35%36%14%
446
11th to 20thDay
2110%30%43%14%
444
21st to endDay
316%31%43%16%
487
August1st to 10thDay
2116%34%35%13%
447
11th to 20thDay
1310%32%34%20%
437
21st to endDay
3112%28%38%19%
495
September1st to 10thDay
1414%23%37%21%
450
11th to 20thDay
1418%28%37%12%
450
21st to endDay
27%14%29%32%16%
450
October1st to 10thDay
26%16%32%29%15%
450
11th to 20thDay
27%15%26%35%16%
350
21st to endDay
36%16%28%34%12%
297
November1st to 10thDay
310%14%29%36%9%
270
11th to 20thDay
28%10%40%28%12%
270
21st to endDay
38%17%34%30%9%
270
December1st to 10thDay
5%7%14%39%30%5%
270
11th to 20thDay
4417%40%27%8%
270
21st to endDay
11%12%16%37%18%4
297
January1st to 10thNight
7%7%18%36%26%5%
760
11th to 20thNight
47%15%47%25%2
734
21st to endNight
8%7%19%40%22%4
792
February1st to 10thNight
47%21%42%23%3
720
11th to 20thNight
7%10%21%39%20%3
704
21st to endNight
8%9%25%38%19%2
592
March1st to 10thNight
5%11%22%40%20%1
720
11th to 20thNight
6%8%23%33%28%3
720
21st to endNight
411%25%38%20%2
792
April1st to 10thNight
312%23%37%24%1
720
11th to 20thNight
312%27%34%20%3
711
21st to endNight
310%22%39%22%4
540
May1st to 10thNight
46%27%39%20%4
540
11th to 20thNight
26%22%36%30%4
531
21st to endNight
38%22%37%28%3
584
June1st to 10thNight
15%19%45%28%3
540
11th to 20thNight
1422%35%33%4
540
21st to endNight
1214%43%37%3
540
July1st to 10thNight
311%35%45%5%
525
11th to 20thNight
38%45%38%5%
522
21st to endNight
37%41%46%3
591
August1st to 10thNight
3110%41%41%4
537
11th to 20thNight
217%38%48%4
606
21st to endNight
28%30%53%7%
792
September1st to 10thNight
328%30%51%7%
720
11th to 20thNight
1111%36%44%7%
720
21st to endNight
2314%32%42%7%
720
October1st to 10thNight
35%15%43%32%3
720
11th to 20thNight
25%14%36%38%6%
720
21st to endNight
37%15%32%37%5%
792
November1st to 10thNight
36%15%36%37%4
740
11th to 20thNight
4412%43%32%4
760
21st to endNight
46%16%39%30%4
760
December1st to 10thNight
7%7%16%39%28%2
760
11th to 20thNight
8%416%42%28%2
760
21st to endNight
9%8%20%39%21%3
836
Page generated at 2024-01-11 01:22:41. Version ac07

Copyright 2024 Attilla Danko


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