Lasqueti Island Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lasqueti Island Observatory clear sky chart from 2005-11-05 to 2017-09-22.

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
42%
14511
8%
46799
7%
14482
44%
14482
14%
35359

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
28%
750
7%
2686
7%
746
30%
746
7%
2238
January16th to endNight
31%
791
4%
2777
4%
791
32%
791
7%
2350
February1st to 15thNight
33%
699
5%
2288
5%
699
35%
699
9%
1884
February16th to endNight
38%
632
11%
2053
11%
632
41%
632
14%
1557
March1st to 15thNight
29%
720
5%
2045
4%
720
31%
720
9%
1732
March16th to endNight
34%
768
7%
2103
4%
768
35%
768
11%
1752
April1st to 15thNight
41%
672
8%
1752
4%
672
43%
672
16%
1382
April16th to endNight
42%
534
9%
1614
7%
534
44%
534
15%
1218
May1st to 15thNight
50%
359
12%
1439
18%
359
53%
359
17%
963
May16th to endNight
54%
375
6%
1395
8%
374
55%
374
14%
1002
June1st to 15thNight
51%
360
2%
1260
2%
360
52%
360
17%
886
June16th to endNight
54%
360
5%
1260
2%
360
55%
360
18%
855
July1st to 15thNight
68%
340
7%
1190
5%
340
70%
340
32%
653
July16th to endNight
74%
376
13%
1275
17%
354
77%
354
37%
646
August1st to 15thNight
77%
466
15%
1540
19%
464
77%
464
35%
819
August16th to endNight
69%
579
18%
1725
15%
579
70%
579
34%
1017
September1st to 15thNight
73%
720
22%
1800
12%
720
75%
720
43%
1087
September16th to endNight
49%
683
16%
1898
11%
683
51%
683
22%
1348
October1st to 15thNight
52%
660
10%
1980
9%
660
54%
660
21%
1392
October16th to endNight
37%
704
7%
2211
5%
704
39%
704
12%
1763
November1st to 15thNight
25%
700
5%
2450
4%
700
27%
700
7%
2067
November16th to endNight
26%
720
5%
2520
4%
720
29%
720
7%
2103
December1st to 15thNight
29%
743
4%
2658
4%
743
31%
743
7%
2238
December16th to endNight
23%
800
6%
2880
3%
800
26%
800
7%
2407

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
18%8%36%5%35%446%32%
48119
Night
21%8%36%5%34446%29%
46948
Cloud CoverDay
20%8%36%5%34446%32%
48119
Night
24%8%36%5%34445%28%
46951
TransparencyDay
52%9%15%16%5%
47771
Night
55%8%13%15%5%
46800
SeeingDay
19%316%25%24%9%
6328
Night
26%316%24%21%7%
14517

By Month

Percentage Cloud Cover NW (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
33%11%5%7%5%25%435%13%
1253
16th to endDay
26%16%5%10%8%25%45%39%
1446
February1st to 15thDay
30%11%47%6%35%44316%
1576
16th to endDay
20%9%48%7%36%6%5%6%21%
1421
March1st to 15thDay
28%13%48%5%36%45%414%
1911
16th to endDay
24%11%48%7%46%34421%
2121
April1st to 15thDay
19%10%5%7%7%45%5%5%6%23%
2193
16th to endDay
19%9%48%5%3445%5%28%
2346
May1st to 15thDay
15%6%36%5%35%447%38%
2511
16th to endDay
15%8%35%5%46%5%5%7%32%
2714
June1st to 15thDay
13%6%37%5%35%45%8%34%
2700
16th to endDay
13%5%26%6%46%46%7%36%
2700
July1st to 15thDay
8%32342335%7%54%
2700
16th to endDay
7%322223336%62%
2807
August1st to 15thDay
6%41332345%6%58%
2409
16th to endDay
8%41442445%8%50%
2477
September1st to 15thDay
9%5%1442436%6%50%
2160
16th to endDay
21%8%36%5%4335%6%32%
1874
October1st to 15thDay
23%10%37%5%44346%25%
1650
16th to endDay
27%14%47%5%3445%6%16%
1659
November1st to 15thDay
33%9%48%5%35%445%17%
1408
16th to endDay
28%13%5%8%5%35%435%15%
1440
December1st to 15thDay
28%14%47%6%25%335%17%
1299
16th to endDay
28%16%48%7%25%42413%
1344
January1st to 15thNight
31%11%47%6%34335%19%
2686
16th to endNight
28%12%48%6%44446%15%
2777
February1st to 15thNight
28%9%47%6%3435%6%20%
2276
16th to endNight
21%7%36%5%35%445%28%
2053
March1st to 15thNight
27%11%47%6%35%5%5%5%17%
2045
16th to endNight
24%9%38%7%35%45%6%20%
2099
April1st to 15thNight
18%9%37%6%45%5%6%7%25%
1752
16th to endNight
19%8%36%6%36%5%5%7%26%
1614
May1st to 15thNight
15%6%36%445%5%5%6%36%
1439
16th to endNight
13%7%47%6%35%5%6%8%31%
1395
June1st to 15thNight
14%7%47%5%36%5%5%6%33%
1260
16th to endNight
12%8%35%5%35%5%5%8%34%
1260
July1st to 15thNight
6%5%23425%35%7%55%
1260
16th to endNight
5%22232435%6%59%
1362
August1st to 15thNight
6%31342435%7%57%
1548
16th to endNight
8%41342345%8%52%
1725
September1st to 15thNight
6%31343335%5%59%
1800
16th to endNight
19%7%25%42345%7%37%
1898
October1st to 15thNight
20%6%25%43434439%
1980
16th to endNight
27%9%36%6%34445%25%
2211
November1st to 15thNight
32%10%46%6%3444417%
2450
16th to endNight
29%11%5%7%7%3444418%
2520
December1st to 15thNight
29%14%46%6%3433418%
2658
16th to endNight
29%13%5%6%5%3434417%
2880

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 15thDay
37%11%47%6%2443314%
1253
16th to endDay
30%15%6%10%6%35%35%39%
1446
February1st to 15thDay
33%11%37%5%4434416%
1576
16th to endDay
21%8%5%8%6%35%45%7%21%
1421
March1st to 15thDay
34%11%5%7%5%25%44414%
1911
16th to endDay
26%10%48%7%4343421%
2121
April1st to 15thDay
21%10%48%6%345%5%6%22%
2193
16th to endDay
23%8%36%5%3446%5%28%
2346
May1st to 15thDay
16%7%25%6%25%346%37%
2511
16th to endDay
17%7%26%6%35%5%6%8%31%
2714
June1st to 15thDay
15%6%36%6%25%45%7%35%
2700
16th to endDay
14%6%26%6%35%46%7%36%
2700
July1st to 15thDay
9%413414447%54%
2700
16th to endDay
8%313213346%60%
2807
August1st to 15thDay
7%32342335%6%57%
2409
16th to endDay
9%5%1343445%8%49%
2477
September1st to 15thDay
9%5%245%23446%49%
2160
16th to endDay
22%8%26%5%3345%6%31%
1874
October1st to 15thDay
26%9%36%6%35%345%24%
1650
16th to endDay
31%11%47%5%34346%16%
1659
November1st to 15thDay
37%9%27%5%3444416%
1408
16th to endDay
32%12%5%9%43433416%
1440
December1st to 15thDay
30%14%5%7%5%3442318%
1299
16th to endDay
34%14%5%6%6%3433413%
1344
January1st to 15thNight
34%12%46%5%2334318%
2685
16th to endNight
31%11%5%8%6%34445%15%
2777
February1st to 15thNight
31%10%37%5%2435%5%19%
2276
16th to endNight
23%9%36%6%345%45%27%
2053
March1st to 15thNight
31%10%5%7%6%3444417%
2045
16th to endNight
28%10%48%6%33445%19%
2103
April1st to 15thNight
21%9%37%7%36%45%6%24%
1752
16th to endNight
21%9%26%6%346%5%6%25%
1614
May1st to 15thNight
17%6%35%6%25%45%6%35%
1439
16th to endNight
14%7%37%6%45%6%5%7%30%
1395
June1st to 15thNight
17%8%36%6%35%45%7%32%
1260
16th to endNight
15%7%45%5%35%5%48%34%
1260
July1st to 15thNight
7%43442445%7%53%
1260
16th to endNight
6%223423446%58%
1362
August1st to 15thNight
7%21332345%8%56%
1548
16th to endNight
9%3245%2345%7%51%
1725
September1st to 15thNight
7%323433345%59%
1800
16th to endNight
20%6%25%413447%37%
1898
October1st to 15thNight
22%5%25%424445%38%
1980
16th to endNight
32%8%35%5%34345%24%
2211
November1st to 15thNight
37%9%46%43333417%
2450
16th to endNight
32%10%5%6%7%2443418%
2520
December1st to 15thNight
32%14%36%5%3433418%
2658
16th to endNight
34%12%36%5%3433318%
2880

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
74%7%6%8%3
1253
16th to endDay
76%8%6%6%
1446
February1st to 15thDay
70%8%8%7%21
1576
16th to endDay
59%10%13%12%3
1421
March1st to 15thDay
71%9%8%9%1
1911
16th to endDay
66%6%12%12%1
2121
April1st to 15thDay
60%10%11%14%3
2193
16th to endDay
56%8%12%15%7%
2346
May1st to 15thDay
45%9%15%21%7%
2511
16th to endDay
49%11%17%18%2
2718
June1st to 15thDay
47%11%18%16%41
2700
16th to endDay
46%11%19%17%5%
2700
July1st to 15thDay
30%9%20%26%11%2
2541
16th to endDay
23%8%24%31%10%1
2631
August1st to 15thDay
27%9%20%29%10%1
2392
16th to endDay
31%10%22%26%6%1
2477
September1st to 15thDay
34%10%17%23%13%1
2160
16th to endDay
53%9%14%15%6%
1874
October1st to 15thDay
60%8%12%12%5%
1650
16th to endDay
68%7%13%8%2
1659
November1st to 15thDay
70%7%9%9%21
1408
16th to endDay
70%7%9%9%3
1440
December1st to 15thDay
71%7%9%7%31
1299
16th to endDay
76%5%7%7%2
1344
January1st to 15thNight
69%7%9%9%4
2686
16th to endNight
68%9%10%9%2
2777
February1st to 15thNight
65%9%11%10%21
2288
16th to endNight
56%7%14%14%5%
2053
March1st to 15thNight
68%8%10%11%2
2045
16th to endNight
64%8%11%13%1
2103
April1st to 15thNight
57%8%12%18%2
1752
16th to endNight
55%8%14%16%5%
1614
May1st to 15thNight
46%8%14%20%8%
1440
16th to endNight
49%11%17%17%3
1395
June1st to 15thNight
49%8%19%16%41
1260
16th to endNight
47%7%16%22%41
1260
July1st to 15thNight
30%6%20%26%13%2
1190
16th to endNight
22%8%21%32%12%1
1275
August1st to 15thNight
25%8%21%28%12%2
1540
16th to endNight
30%8%21%29%8%2
1725
September1st to 15thNight
25%7%16%27%19%2
1800
16th to endNight
46%8%14%20%7%1
1898
October1st to 15thNight
47%7%17%19%7%
1980
16th to endNight
61%8%15%11%3
2211
November1st to 15thNight
69%8%10%7%21
2450
16th to endNight
68%8%8%10%4
2520
December1st to 15thNight
70%7%10%7%3
2658
16th to endNight
69%7%10%8%3
2880

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
23%15%21%25%15%
60
16th to endDay
44%22%17%12%2
109
February1st to 15thDay
35%6%17%19%19%
236
16th to endDay
26%5%24%21%16%5%
211
March1st to 15thDay
40%7%24%13%10%1
266
16th to endDay
30%6%25%21%10%4
288
April1st to 15thDay
23%6%24%24%15%5%
269
16th to endDay
22%424%29%13%5%
270
May1st to 15thDay
19%415%29%23%7%
288
16th to endDay
14%114%25%33%10%
429
June1st to 15thDay
13%218%28%28%8%
495
16th to endDay
14%117%31%25%9%
495
July1st to 15thDay
8%19%28%35%15%
475
16th to endDay
6%18%27%41%14%
476
August1st to 15thDay
8%7%21%38%23%
315
16th to endDay
9%110%25%37%15%
332
September1st to 15thDay
11%212%30%26%15%
315
16th to endDay
25%216%27%16%11%
280
October1st to 15thDay
30%317%24%18%6%
255
16th to endDay
35%219%23%13%5%
220
November1st to 15thDay
43%8%26%15%5%1
60
16th to endDay
40%313%13%15%15%
60
December1st to 15thDay
45%21%15%15%3
60
16th to endDay
32%7%20%25%9%4
64
January1st to 15thNight
36%6%16%19%16%4
750
16th to endNight
35%317%19%18%5%
791
February1st to 15thNight
31%416%25%17%3
704
16th to endNight
24%6%19%25%20%3
632
March1st to 15thNight
34%6%20%21%12%4
720
16th to endNight
29%418%25%15%6%
768
April1st to 15thNight
23%318%25%22%6%
672
16th to endNight
24%217%28%21%4
534
May1st to 15thNight
18%217%26%25%9%
360
16th to endNight
14%312%29%30%9%
375
June1st to 15thNight
18%312%31%25%9%
360
16th to endNight
16%114%31%28%7%
360
July1st to 15thNight
10%29%27%34%15%
340
16th to endNight
6%9%26%40%17%
376
August1st to 15thNight
8%323%44%18%
466
16th to endNight
9%19%25%41%11%
579
September1st to 15thNight
8%10%26%32%21%
720
16th to endNight
24%116%22%24%11%
683
October1st to 15thNight
24%212%28%21%9%
660
16th to endNight
34%316%23%16%6%
704
November1st to 15thNight
39%419%25%10%1
700
16th to endNight
35%6%18%21%13%5%
720
December1st to 15thNight
36%418%22%16%2
743
16th to endNight
38%6%24%19%9%1
800
Page generated at 2017-09-23 03:43:46. Version ac04

Copyright 2017 A. Danko


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