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 2019-06-19.

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
43%
16785
9%
53900
8%
16756
45%
16756
15%
40543

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%
900
7%
3136
7%
896
30%
896
7%
2628
January16th to endNight
29%
941
3%
3239
3%
941
30%
941
7%
2755
February1st to 15thNight
34%
819
7%
2678
6%
819
36%
819
9%
2194
February16th to endNight
40%
736
11%
2391
10%
736
43%
736
14%
1819
March1st to 15thNight
35%
840
8%
2387
6%
840
37%
840
12%
1952
March16th to endNight
39%
896
8%
2454
5%
896
40%
896
13%
1987
April1st to 15thNight
39%
784
8%
2044
4%
784
41%
784
14%
1643
April16th to endNight
44%
618
10%
1866
7%
618
46%
618
16%
1391
May1st to 15thNight
57%
419
13%
1679
20%
419
60%
419
19%
1086
May16th to endNight
55%
439
7%
1635
10%
438
57%
438
16%
1143
June1st to 15thNight
54%
420
3%
1470
3%
420
54%
420
17%
1024
June16th to endNight
56%
398
5%
1393
2%
398
57%
398
19%
931
July1st to 15thNight
69%
370
8%
1295
6%
370
71%
370
33%
709
July16th to endNight
78%
408
13%
1390
18%
386
81%
386
39%
687
August1st to 15thNight
77%
496
16%
1642
21%
494
77%
494
36%
861
August16th to endNight
71%
627
19%
1869
16%
627
72%
627
34%
1102
September1st to 15thNight
71%
780
21%
1950
12%
780
73%
780
41%
1206
September16th to endNight
50%
776
15%
2157
11%
776
52%
776
22%
1540
October1st to 15thNight
53%
780
11%
2340
10%
780
54%
780
22%
1621
October16th to endNight
41%
832
9%
2614
8%
832
43%
832
14%
2016
November1st to 15thNight
27%
820
5%
2870
5%
820
30%
820
7%
2396
November16th to endNight
27%
840
5%
2940
4%
840
29%
840
7%
2466
December1st to 15thNight
30%
886
6%
3101
5%
886
32%
886
8%
2566
December16th to endNight
22%
960
6%
3360
3%
960
26%
960
7%
2820

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%34446%33%
54853
Night
21%9%36%5%34446%29%
54049
Cloud CoverDay
20%8%36%5%34446%32%
54853
Night
24%8%36%5%34445%29%
54052
TransparencyDay
52%9%14%17%5%
54505
Night
55%8%13%15%5%
53901
SeeingDay
20%216%25%24%10%
8494
Night
26%315%24%21%7%
16791

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
34%11%5%8%5%35%43413%
1463
16th to endDay
26%16%5%10%8%35%45%49%
1688
February1st to 15thDay
29%12%48%6%35%44317%
1846
16th to endDay
20%9%47%7%36%6%46%22%
1655
March1st to 15thDay
26%12%48%5%46%45%5%18%
2229
16th to endDay
22%10%48%7%45%34423%
2474
April1st to 15thDay
20%10%5%7%7%45%5%5%6%22%
2560
16th to endDay
19%9%47%5%3445%5%30%
2698
May1st to 15thDay
13%6%25%5%35%447%40%
2931
16th to endDay
14%8%25%5%45%5%5%7%34%
3178
June1st to 15thDay
14%6%37%5%35%5%5%8%34%
3150
16th to endDay
12%5%25%6%45%46%8%37%
2975
July1st to 15thDay
8%424423347%54%
2925
16th to endDay
7%222223346%64%
3044
August1st to 15thDay
6%413323446%59%
2559
16th to endDay
8%41442445%8%51%
2685
September1st to 15thDay
10%5%2442436%6%49%
2340
16th to endDay
21%8%36%5%43346%31%
2132
October1st to 15thDay
23%10%37%5%34345%27%
1950
16th to endDay
27%13%47%5%34447%18%
1960
November1st to 15thDay
32%9%38%5%34345%17%
1648
16th to endDay
30%14%5%8%5%35%435%15%
1680
December1st to 15thDay
27%14%47%6%25%345%16%
1515
16th to endDay
30%15%48%7%25%42413%
1568
January1st to 15thNight
32%11%47%6%34335%17%
3136
16th to endNight
28%12%48%7%44446%14%
3239
February1st to 15thNight
28%10%47%5%34346%21%
2666
16th to endNight
21%8%37%5%36%445%28%
2391
March1st to 15thNight
25%10%46%6%35%5%5%5%20%
2387
16th to endNight
22%10%38%7%35%45%6%23%
2450
April1st to 15thNight
19%10%37%7%45%5%5%7%23%
2044
16th to endNight
20%7%36%6%36%5%5%6%28%
1866
May1st to 15thNight
14%6%35%445%5%6%6%38%
1679
16th to endNight
13%6%36%6%35%5%6%8%33%
1635
June1st to 15thNight
13%7%37%6%36%5%5%6%34%
1470
16th to endNight
12%7%35%5%35%5%5%8%36%
1393
July1st to 15thNight
6%5%2332435%7%55%
1365
16th to endNight
5%222324346%61%
1477
August1st to 15thNight
6%31332335%7%58%
1650
16th to endNight
7%41342345%8%52%
1869
September1st to 15thNight
6%31343435%5%57%
1950
16th to endNight
20%7%35%423446%37%
2157
October1st to 15thNight
19%6%25%423345%40%
2340
16th to endNight
26%8%36%6%24445%28%
2614
November1st to 15thNight
32%10%46%6%3444418%
2870
16th to endNight
29%11%47%6%3444418%
2940
December1st to 15thNight
28%13%46%6%3433419%
3101
16th to endNight
31%13%5%6%5%3433417%
3360

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%48%5%3443313%
1463
16th to endDay
30%15%6%9%6%35%3439%
1688
February1st to 15thDay
33%12%47%5%4433417%
1846
16th to endDay
22%9%5%7%6%35%45%6%22%
1655
March1st to 15thDay
31%10%46%5%35%44418%
2229
16th to endDay
24%10%48%7%4433423%
2474
April1st to 15thDay
23%10%48%6%345%5%6%21%
2560
16th to endDay
23%8%36%5%3435%5%30%
2698
May1st to 15thDay
15%6%25%6%25%446%40%
2931
16th to endDay
15%7%26%5%35%5%6%7%33%
3178
June1st to 15thDay
15%6%36%6%26%45%7%34%
3150
16th to endDay
13%6%25%6%35%46%7%36%
2975
July1st to 15thDay
9%5%13414347%54%
2925
16th to endDay
8%213212336%62%
3044
August1st to 15thDay
7%31342335%6%58%
2559
16th to endDay
8%5%1343345%8%50%
2685
September1st to 15thDay
10%5%245%2345%6%48%
2340
16th to endDay
22%9%36%5%33446%30%
2132
October1st to 15thDay
25%9%35%5%35%345%27%
1950
16th to endDay
31%11%47%5%33446%18%
1960
November1st to 15thDay
36%9%37%5%3444417%
1648
16th to endDay
34%12%48%43433316%
1680
December1st to 15thDay
29%13%5%8%5%34435%17%
1515
16th to endDay
35%13%5%6%6%3433313%
1568
January1st to 15thNight
35%11%46%5%2333417%
3135
16th to endNight
30%11%5%8%6%34445%14%
3239
February1st to 15thNight
31%11%37%424345%20%
2666
16th to endNight
23%9%36%6%3444427%
2391
March1st to 15thNight
29%9%46%6%345%45%20%
2387
16th to endNight
26%9%47%6%3345%5%22%
2454
April1st to 15thNight
23%9%37%6%36%446%22%
2044
16th to endNight
21%9%26%5%346%5%6%27%
1866
May1st to 15thNight
15%6%35%6%25%45%6%37%
1679
16th to endNight
14%6%37%6%45%5%5%7%32%
1635
June1st to 15thNight
17%7%36%6%35%5%5%7%33%
1470
16th to endNight
14%7%45%5%35%5%48%35%
1393
July1st to 15thNight
8%434424446%53%
1365
16th to endNight
6%223423446%60%
1477
August1st to 15thNight
6%21332335%8%57%
1650
16th to endNight
9%3245%2345%7%51%
1869
September1st to 15thNight
7%323434345%57%
1950
16th to endNight
21%7%25%413446%37%
2157
October1st to 15thNight
21%5%25%424345%39%
2340
16th to endNight
30%7%35%433345%27%
2614
November1st to 15thNight
37%9%46%43334418%
2870
16th to endNight
34%9%46%6%2443318%
2940
December1st to 15thNight
31%13%37%5%3433420%
3101
16th to endNight
36%12%36%5%2433418%
3360

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%7%3
1463
16th to endDay
76%9%7%6%
1688
February1st to 15thDay
70%8%8%8%31
1846
16th to endDay
59%10%13%12%3
1655
March1st to 15thDay
67%9%10%10%2
2229
16th to endDay
64%6%13%13%2
2474
April1st to 15thDay
61%10%11%13%3
2560
16th to endDay
54%7%11%16%8%
2698
May1st to 15thDay
42%9%16%21%7%
2931
16th to endDay
46%11%18%20%3
3182
June1st to 15thDay
47%11%18%17%41
3150
16th to endDay
45%10%19%18%5%
2975
July1st to 15thDay
31%8%19%26%11%2
2766
16th to endDay
21%8%22%32%13%1
2868
August1st to 15thDay
26%9%20%30%10%1
2542
16th to endDay
30%10%23%27%7%1
2685
September1st to 15thDay
34%10%17%22%12%1
2340
16th to endDay
53%9%15%15%6%
2132
October1st to 15thDay
58%8%13%13%5%
1950
16th to endDay
66%7%13%10%2
1960
November1st to 15thDay
68%7%9%9%31
1648
16th to endDay
71%7%9%8%2
1680
December1st to 15thDay
70%7%9%8%21
1515
16th to endDay
75%5%7%7%3
1568
January1st to 15thNight
69%7%9%9%3
3136
16th to endNight
69%8%10%8%2
3239
February1st to 15thNight
65%8%11%10%31
2678
16th to endNight
57%7%13%14%6%
2391
March1st to 15thNight
63%7%11%13%2
2387
16th to endNight
61%8%12%14%2
2454
April1st to 15thNight
59%8%11%17%2
2044
16th to endNight
54%7%12%17%7%
1866
May1st to 15thNight
44%8%16%21%9%
1680
16th to endNight
47%10%17%19%3
1635
June1st to 15thNight
48%8%19%17%41
1470
16th to endNight
46%7%17%22%5%1
1393
July1st to 15thNight
30%6%20%26%13%3
1295
16th to endNight
21%8%20%32%15%2
1390
August1st to 15thNight
25%8%20%29%13%2
1642
16th to endNight
30%8%20%29%9%2
1869
September1st to 15thNight
28%8%15%27%18%2
1950
16th to endNight
47%7%14%21%7%1
2157
October1st to 15thNight
46%7%16%20%8%
2340
16th to endNight
57%8%14%14%4
2614
November1st to 15thNight
68%8%10%7%31
2870
16th to endNight
68%8%8%9%3
2940
December1st to 15thNight
68%7%10%9%3
3101
16th to endNight
70%7%9%8%3
3360

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
33%16%17%22%9%
120
16th to endDay
40%223%18%9%4
181
February1st to 15thDay
36%5%20%18%17%
326
16th to endDay
27%425%22%15%4
289
March1st to 15thDay
34%5%18%20%18%3
382
16th to endDay
26%5%20%27%15%4
416
April1st to 15thDay
28%6%24%23%13%3
389
16th to endDay
23%422%26%15%6%
378
May1st to 15thDay
15%312%31%26%9%
408
16th to endDay
12%113%28%32%11%
573
June1st to 15thDay
15%218%27%27%8%
645
16th to endDay
13%119%30%26%8%
587
July1st to 15thDay
9%111%28%34%14%
550
16th to endDay
5%8%24%40%20%
553
August1st to 15thDay
7%6%20%37%26%
359
16th to endDay
8%110%23%37%17%
396
September1st to 15thDay
13%212%30%25%14%
375
16th to endDay
25%213%27%20%10%
375
October1st to 15thDay
29%218%25%16%7%
375
16th to endDay
34%217%19%17%8%
329
November1st to 15thDay
35%7%26%18%8%3
120
16th to endDay
46%410%13%13%11%
120
December1st to 15thDay
35%112%20%24%5%
120
16th to endDay
40%5%22%22%6%2
128
January1st to 15thNight
38%5%15%19%17%4
900
16th to endNight
35%318%18%18%4
941
February1st to 15thNight
33%417%25%16%3
824
16th to endNight
25%5%18%27%19%4
736
March1st to 15thNight
31%6%18%22%15%6%
840
16th to endNight
27%416%26%17%7%
896
April1st to 15thNight
25%319%24%21%5%
784
16th to endNight
25%217%27%21%5%
618
May1st to 15thNight
17%215%27%27%9%
420
16th to endNight
13%311%28%32%10%
439
June1st to 15thNight
18%211%32%25%9%
420
16th to endNight
15%114%32%28%7%
398
July1st to 15thNight
10%19%28%34%14%
370
16th to endNight
5%8%24%41%19%
408
August1st to 15thNight
8%322%45%19%
496
16th to endNight
9%19%25%41%12%
627
September1st to 15thNight
9%10%26%32%21%
780
16th to endNight
25%115%21%25%10%
776
October1st to 15thNight
23%212%28%22%9%
780
16th to endNight
32%314%23%17%7%
832
November1st to 15thNight
39%418%25%11%1
820
16th to endNight
36%6%18%20%13%5%
840
December1st to 15thNight
34%317%22%18%3
886
16th to endNight
40%5%24%19%8%1
960
Page generated at 2019-06-20 05:02:30. Version ac04

Copyright 2019 A. Danko


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