Channel-Port aux Basques
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Channel-Port aux Basques clear sky chart from 2005-11-05 to 2019-06-02.

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
22%
17566
8%
53814
4%
17519
26%
17519
11%
43187

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
7%
899
3%
2926
0%
896
10%
896
3%
2657
January16th to endNight
9%
960
3%
3136
2%
960
10%
960
4%
2842
February1st to 15thNight
9%
842
3%
2739
1%
839
12%
839
3%
2466
February16th to endNight
16%
735
6%
2246
2%
735
20%
735
8%
1837
March1st to 15thNight
18%
839
11%
2508
4%
836
26%
836
12%
1969
March16th to endNight
23%
755
11%
2329
5%
755
29%
755
12%
1763
April1st to 15thNight
23%
629
9%
2096
6%
629
28%
629
12%
1571
April16th to endNight
26%
623
11%
1903
7%
623
32%
623
15%
1414
May1st to 15thNight
35%
630
14%
1680
6%
630
40%
630
21%
1236
May16th to endNight
31%
657
9%
1752
4%
656
34%
656
18%
1330
June1st to 15thNight
30%
589
4%
1570
2%
589
32%
589
15%
1257
June16th to endNight
34%
585
5%
1560
3%
585
35%
585
17%
1216
July1st to 15thNight
42%
555
6%
1480
4%
555
44%
555
18%
1134
July16th to endNight
37%
613
7%
1547
5%
580
39%
580
16%
1227
August1st to 15thNight
44%
574
10%
1522
6%
570
47%
570
21%
1140
August16th to endNight
44%
621
10%
2010
9%
621
47%
621
18%
1409
September1st to 15thNight
36%
585
12%
1950
9%
585
41%
585
17%
1362
September16th to endNight
33%
583
14%
2119
10%
583
40%
583
18%
1403
October1st to 15thNight
27%
764
12%
2324
6%
764
33%
764
16%
1681
October16th to endNight
15%
888
7%
2677
2%
888
19%
888
10%
2151
November1st to 15thNight
17%
880
7%
2724
3%
880
21%
880
9%
2205
November16th to endNight
13%
900
5%
2940
2%
900
16%
900
6%
2504
December1st to 15thNight
10%
900
4%
2940
1%
900
14%
900
4%
2628
December16th to endNight
9%
960
4%
3136
3%
960
11%
960
4%
2785

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
24%12%5%8%6%34345%21%
54524
Night
23%13%6%9%7%3444418%
53997
TransparencyDay
63%411%14%5%
54213
Night
65%49%13%5%
53826
SeeingDay
31%11%23%21%9%1
10188
Night
30%12%24%23%8%
17568

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
18%18%11%17%10%333136%
1672
16th to endDay
18%17%11%15%16%442124
1792
February1st to 15thDay
18%13%8%18%15%6%5%2326%
1782
16th to endDay
15%14%8%12%13%3434414%
1799
March1st to 15thDay
17%11%6%10%10%45%45%419%
2090
16th to endDay
16%14%6%9%8%4445%5%20%
2596
April1st to 15thDay
24%14%5%7%5%34335%21%
2513
16th to endDay
27%10%45%423345%27%
2661
May1st to 15thDay
25%9%26%424435%31%
2932
16th to endDay
24%9%35%434446%27%
3066
June1st to 15thDay
28%9%46%5%24346%24%
2744
16th to endDay
31%9%45%5%23336%25%
2730
July1st to 15thDay
22%7%35%42445%6%31%
2730
16th to endDay
31%7%26%5%34446%23%
2877
August1st to 15thDay
24%8%36%5%3346%8%24%
2680
16th to endDay
23%7%26%5%2445%8%28%
2542
September1st to 15thDay
26%6%25%5%2446%7%27%
2340
16th to endDay
24%6%26%435%45%7%28%
2171
October1st to 15thDay
24%10%36%5%44446%24%
1966
16th to endDay
31%15%47%5%34445%14%
1898
November1st to 15thDay
29%18%48%6%2323414%
1791
16th to endDay
24%22%7%10%6%3442410%
1680
December1st to 15thDay
25%22%9%12%7%342316%
1680
16th to endDay
19%21%10%15%9%243327%
1792
January1st to 15thNight
22%17%10%15%10%343225%
2926
16th to endNight
19%16%9%16%13%5%32226%
3136
February1st to 15thNight
19%13%8%18%14%5%43325%
2738
16th to endNight
14%15%8%13%10%35%44415%
2246
March1st to 15thNight
18%12%6%10%8%43446%21%
2507
16th to endNight
19%13%5%8%7%35%445%22%
2329
April1st to 15thNight
23%11%5%8%5%34445%22%
2096
16th to endNight
24%10%36%5%24335%28%
1903
May1st to 15thNight
25%8%35%423335%33%
1680
16th to endNight
28%10%35%424346%27%
1750
June1st to 15thNight
29%10%46%424335%23%
1570
16th to endNight
28%10%446%22346%24%
1560
July1st to 15thNight
21%8%47%5%345%45%28%
1560
16th to endNight
32%7%45%324446%22%
1643
August1st to 15thNight
24%7%25%6%35%46%7%27%
1533
16th to endNight
21%8%36%435%45%6%30%
2010
September1st to 15thNight
26%7%14425%435%32%
1950
16th to endNight
23%6%245%3345%8%31%
2119
October1st to 15thNight
24%8%26%6%3445%5%26%
2324
16th to endNight
25%14%48%7%44445%15%
2677
November1st to 15thNight
27%14%5%8%6%34445%16%
2724
16th to endNight
28%19%7%8%5%3433410%
2940
December1st to 15thNight
24%22%10%10%8%233227%
2940
16th to endNight
22%20%10%14%8%333227%
3136

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
81%5%5%5%1
1673
16th to endDay
84%35%5%1
1792
February1st to 15thDay
82%46%6%
1785
16th to endDay
70%5%8%11%4
1799
March1st to 15thDay
63%410%13%7%
2100
16th to endDay
61%49%16%6%1
2596
April1st to 15thDay
62%47%15%8%1
2513
16th to endDay
58%310%15%10%1
2661
May1st to 15thDay
55%311%20%8%
2932
16th to endDay
56%413%17%6%1
3070
June1st to 15thDay
60%410%17%6%
2744
16th to endDay
61%311%15%6%
2730
July1st to 15thDay
51%5%14%21%5%
2582
16th to endDay
61%412%15%5%
2710
August1st to 15thDay
55%5%16%16%4
2666
16th to endDay
52%5%17%19%4
2542
September1st to 15thDay
50%5%16%20%7%
2340
16th to endDay
50%6%16%19%6%
2171
October1st to 15thDay
55%5%14%15%8%
1966
16th to endDay
69%49%13%3
1898
November1st to 15thDay
72%49%10%3
1791
16th to endDay
75%6%7%7%2
1680
December1st to 15thDay
81%45%6%1
1680
16th to endDay
79%45%7%2
1792
January1st to 15thNight
80%5%5%6%1
2926
16th to endNight
81%446%1
3136
February1st to 15thNight
81%46%7%1
2739
16th to endNight
67%5%8%12%4
2246
March1st to 15thNight
62%410%14%7%
2520
16th to endNight
59%5%9%17%6%1
2329
April1st to 15thNight
59%5%10%14%9%1
2096
16th to endNight
58%310%14%11%1
1903
May1st to 15thNight
54%39%21%10%1
1680
16th to endNight
58%39%20%7%
1752
June1st to 15thNight
63%310%16%5%
1570
16th to endNight
61%210%16%8%
1560
July1st to 15thNight
57%411%17%9%
1480
16th to endNight
62%311%16%5%
1547
August1st to 15thNight
52%5%16%18%41
1522
16th to endNight
52%416%20%5%
2010
September1st to 15thNight
51%5%12%22%7%
1950
16th to endNight
47%5%16%22%7%
2119
October1st to 15thNight
53%5%13%18%8%
2324
16th to endNight
65%5%11%13%4
2677
November1st to 15thNight
65%6%12%12%3
2724
16th to endNight
73%5%9%7%3
2940
December1st to 15thNight
79%5%7%6%1
2940
16th to endNight
78%5%5%7%2
3136

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
28%20%35%11%3
330
16th to endDay
27%21%29%17%2
352
February1st to 15thDay
25%26%30%14%3
326
16th to endDay
26%23%24%16%7%1
290
March1st to 15thDay
23%18%28%21%6%1
330
16th to endDay
26%17%26%19%7%3
414
April1st to 15thDay
31%20%25%14%7%
390
16th to endDay
35%7%23%21%9%1
509
May1st to 15thDay
32%5%22%23%11%3
618
16th to endDay
30%8%23%22%11%2
679
June1st to 15thDay
35%5%13%31%11%1
575
16th to endDay
38%417%27%10%1
570
July1st to 15thDay
30%416%31%15%2
550
16th to endDay
41%315%24%13%1
594
August1st to 15thDay
32%315%26%20%2
550
16th to endDay
29%316%29%17%3
426
September1st to 15thDay
26%5%28%26%11%1
375
16th to endDay
24%9%31%24%7%2
322
October1st to 15thDay
28%10%30%17%9%2
315
16th to endDay
34%16%27%13%6%
336
November1st to 15thDay
32%17%23%16%8%1
325
16th to endDay
33%18%25%18%4
330
December1st to 15thDay
29%18%34%13%3
330
16th to endDay
27%24%25%14%6%1
352
January1st to 15thNight
28%20%30%17%2
900
16th to endNight
27%20%31%16%3
960
February1st to 15thNight
26%19%32%17%3
842
16th to endNight
22%15%31%22%6%1
735
March1st to 15thNight
23%18%29%22%6%
840
16th to endNight
25%13%28%22%8%1
755
April1st to 15thNight
27%12%27%25%6%1
629
16th to endNight
30%7%24%28%7%
623
May1st to 15thNight
29%423%27%12%2
630
16th to endNight
35%5%19%27%10%1
657
June1st to 15thNight
39%417%26%11%1
589
16th to endNight
36%414%28%12%2
585
July1st to 15thNight
28%216%34%17%
555
16th to endNight
38%311%28%16%1
613
August1st to 15thNight
30%212%31%20%2
574
16th to endNight
25%218%29%22%1
621
September1st to 15thNight
30%420%30%12%1
585
16th to endNight
26%7%27%26%11%
583
October1st to 15thNight
27%9%26%26%9%1
764
16th to endNight
33%12%28%20%4
888
November1st to 15thNight
32%13%26%17%7%1
880
16th to endNight
35%16%25%18%4
900
December1st to 15thNight
35%18%26%15%4
900
16th to endNight
30%20%27%14%5%1
960
Page generated at 2019-06-02 20:43:10. Version ac04

Copyright 2019 A. Danko


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