Chisasibi
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chisasibi clear sky chart from 2005-11-05 to 2017-09-19.

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
34%
15113
6%
46747
5%
15083
35%
15083
10%
38134

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%
899
2%
2690
2%
896
28%
896
4%
2461
January16th to endNight
41%
960
7%
2880
6%
960
42%
960
7%
2520
February1st to 15thNight
45%
752
6%
2384
6%
749
46%
749
8%
2007
February16th to endNight
46%
631
10%
2051
10%
631
47%
631
12%
1607
March1st to 15thNight
45%
720
14%
2095
13%
720
47%
720
17%
1569
March16th to endNight
43%
768
13%
2079
9%
768
46%
768
19%
1563
April1st to 15thNight
39%
638
13%
1716
8%
638
42%
638
17%
1309
April16th to endNight
47%
456
15%
1536
16%
456
51%
456
21%
1023
May1st to 15thNight
36%
360
8%
1398
9%
360
39%
360
16%
940
May16th to endNight
37%
374
1%
1274
0%
374
37%
374
16%
915
June1st to 15thNight
50%
360
0%
1080
0%
360
50%
360
27%
685
June16th to endNight
44%
360
0%
1080
0%
360
44%
360
24%
735
July1st to 15thNight
43%
340
0%
1113
0%
340
43%
340
16%
806
July16th to endNight
45%
376
1%
1240
0%
354
46%
354
15%
897
August1st to 15thNight
43%
359
6%
1363
7%
357
45%
357
12%
1009
August16th to endNight
41%
570
8%
1716
8%
570
42%
570
15%
1323
September1st to 15thNight
32%
696
7%
1776
3%
696
34%
696
15%
1420
September16th to endNight
29%
673
7%
1865
4%
673
30%
673
13%
1496
October1st to 15thNight
20%
660
6%
1980
4%
660
24%
660
8%
1664
October16th to endNight
23%
704
4%
2332
5%
704
24%
704
5%
2064
November1st to 15thNight
14%
700
3%
2452
3%
700
15%
700
3%
2229
November16th to endNight
17%
835
4%
2695
3%
835
18%
835
4%
2477
December1st to 15thNight
19%
930
3%
2880
2%
930
20%
930
3%
2674
December16th to endNight
30%
992
5%
3072
5%
992
31%
992
5%
2741

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
17%11%48%7%45%5%5%6%22%
48095
Night
16%13%5%9%8%46%6%5%417%
46892
TransparencyDay
61%5%11%15%5%
47757
Night
66%6%9%12%4
46748
SeeingDay
23%5%22%26%16%6%
6572
Night
22%6%20%29%17%3
15116

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
13%14%6%14%12%8%10%8%5%21
1247
16th to endDay
8%10%6%12%13%9%11%10%8%26%
1344
February1st to 15thDay
48%5%10%12%7%13%13%11%28%
1476
16th to endDay
7%14%5%10%8%5%8%11%9%5%13%
1422
March1st to 15thDay
8%10%49%10%5%9%11%7%6%15%
1850
16th to endDay
9%9%5%8%7%6%9%9%6%5%22%
2144
April1st to 15thDay
13%12%6%10%8%46%435%24%
2243
16th to endDay
12%10%49%9%24335%33%
2424
May1st to 15thDay
18%9%5%9%6%23436%30%
2551
16th to endDay
16%8%5%8%5%35%5%5%8%27%
2839
June1st to 15thDay
14%6%35%435%447%41%
2880
16th to endDay
14%8%36%5%2445%7%36%
2880
July1st to 15thDay
19%9%35%6%25%45%7%29%
2778
16th to endDay
18%9%47%5%3445%8%28%
2844
August1st to 15thDay
23%10%37%5%3445%7%24%
2589
16th to endDay
24%9%36%43445%7%26%
2485
September1st to 15thDay
26%11%37%5%34337%20%
2172
16th to endDay
29%13%47%6%2444420%
1841
October1st to 15thDay
28%18%48%7%2333416%
1650
16th to endDay
29%23%6%8%5%3222311%
1538
November1st to 15thDay
28%27%7%8%5%233337%
1406
16th to endDay
17%20%9%17%9%332238%
1260
December1st to 15thDay
11%17%9%16%16%6%44328%
1080
16th to endDay
9%13%8%11%11%8%12%6%3310%
1152
January1st to 15thNight
15%14%6%13%12%7%9%8%6%23
2690
16th to endNight
9%11%5%11%13%6%11%12%6%27%
2880
February1st to 15thNight
47%5%12%12%6%14%13%10%47%
2382
16th to endNight
6%14%6%9%8%49%12%9%6%13%
2051
March1st to 15thNight
7%7%410%8%5%8%10%9%6%21%
2083
16th to endNight
10%10%37%7%49%7%5%7%25%
2079
April1st to 15thNight
14%11%48%7%45%45%6%26%
1716
16th to endNight
13%9%36%5%43436%37%
1536
May1st to 15thNight
19%8%47%5%24447%32%
1398
16th to endNight
17%9%5%8%5%245%6%6%28%
1273
June1st to 15thNight
16%5%25%3245%6%6%40%
1080
16th to endNight
14%7%27%4345%5%5%38%
1080
July1st to 15thNight
19%10%5%6%5%245%5%7%27%
1181
16th to endNight
17%10%47%6%346%5%7%25%
1324
August1st to 15thNight
24%9%37%6%3445%5%25%
1371
16th to endNight
20%11%47%5%2445%7%25%
1716
September1st to 15thNight
23%10%47%5%35%5%45%24%
1776
16th to endNight
26%11%46%6%24446%21%
1865
October1st to 15thNight
28%16%48%6%3342417%
1980
16th to endNight
29%22%5%7%5%2333312%
2332
November1st to 15thNight
31%25%5%8%4333129%
2452
16th to endNight
18%22%10%16%7%342328%
2695
December1st to 15thNight
12%18%10%17%16%45%2118%
2880
16th to endNight
12%12%7%11%14%8%10%6%339%
3072

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%7%5%41
1248
16th to endDay
74%5%6%8%4
1344
February1st to 15thDay
65%8%9%11%5%
1478
16th to endDay
63%5%12%12%4
1422
March1st to 15thDay
61%5%8%16%7%
1861
16th to endDay
58%5%12%15%7%
2144
April1st to 15thDay
61%36%18%8%
2243
16th to endDay
54%39%21%10%
2424
May1st to 15thDay
56%38%24%7%
2551
16th to endDay
53%7%10%19%8%
2843
June1st to 15thDay
42%5%10%28%13%
2880
16th to endDay
46%412%23%11%1
2880
July1st to 15thDay
52%7%13%21%5%
2617
16th to endDay
52%8%17%19%2
2665
August1st to 15thDay
58%8%17%12%2
2573
16th to endDay
56%6%17%16%2
2485
September1st to 15thDay
65%6%13%13%1
2172
16th to endDay
67%6%11%12%2
1841
October1st to 15thDay
73%410%9%2
1650
16th to endDay
78%5%7%8%
1538
November1st to 15thDay
83%35%5%1
1406
16th to endDay
81%5%6%5%1
1260
December1st to 15thDay
82%5%5%41
1080
16th to endDay
77%48%5%3
1152
January1st to 15thNight
80%6%6%41
2690
16th to endNight
72%8%6%8%3
2880
February1st to 15thNight
68%8%7%11%3
2384
16th to endNight
61%7%12%13%4
2051
March1st to 15thNight
53%7%11%18%8%
2095
16th to endNight
54%5%10%18%10%
2079
April1st to 15thNight
57%47%19%9%
1716
16th to endNight
47%310%23%14%
1536
May1st to 15thNight
51%48%22%11%1
1398
16th to endNight
54%5%9%20%9%
1275
June1st to 15thNight
41%49%28%15%
1080
16th to endNight
46%411%21%14%1
1080
July1st to 15thNight
53%7%12%22%5%
1113
16th to endNight
54%6%16%19%3
1240
August1st to 15thNight
59%5%16%14%3
1363
16th to endNight
57%7%14%17%3
1716
September1st to 15thNight
60%7%16%13%3
1776
16th to endNight
63%6%15%13%2
1865
October1st to 15thNight
71%5%10%9%3
1980
16th to endNight
77%6%8%6%1
2332
November1st to 15thNight
82%45%6%1
2452
16th to endNight
82%5%5%5%1
2695
December1st to 15thNight
85%345%
2880
16th to endNight
77%6%6%7%2
3072

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
13%10%26%26%16%6%
60
16th to endDay
23%6%18%25%21%4
64
February1st to 15thDay
14%213%29%29%9%
81
16th to endDay
13%130%33%17%3
81
March1st to 15thDay
15%7%22%22%19%12%
226
16th to endDay
12%6%26%32%17%5%
288
April1st to 15thDay
15%6%21%27%22%6%
270
16th to endDay
15%7%26%24%15%11%
270
May1st to 15thDay
22%422%26%16%7%
328
16th to endDay
18%7%26%28%14%4
552
June1st to 15thDay
18%5%24%26%18%6%
675
16th to endDay
19%5%21%32%16%4
675
July1st to 15thDay
23%5%22%29%14%3
551
16th to endDay
22%223%27%17%6%
515
August1st to 15thDay
34%314%21%17%8%
382
16th to endDay
31%314%25%14%9%
332
September1st to 15thDay
31%6%24%21%12%3
315
16th to endDay
32%9%27%19%9%1
266
October1st to 15thDay
39%5%21%18%9%3
255
16th to endDay
41%9%12%17%13%5%
142
November1st to 15thDay
48%8%15%18%5%5%
60
16th to endDay
25%10%20%23%16%5%
60
December1st to 15thDay
13%131%31%20%1
60
16th to endDay
15%328%35%14%3
64
January1st to 15thNight
20%6%20%29%16%5%
901
16th to endNight
14%415%33%24%7%
960
February1st to 15thNight
7%317%37%26%6%
752
16th to endNight
13%414%30%24%12%
631
March1st to 15thNight
11%5%21%34%21%5%
720
16th to endNight
15%5%23%33%19%2
768
April1st to 15thNight
17%423%33%16%4
638
16th to endNight
18%420%34%19%2
456
May1st to 15thNight
21%5%28%29%12%2
360
16th to endNight
21%7%24%33%13%1
375
June1st to 15thNight
20%320%33%19%1
360
16th to endNight
18%423%35%15%2
360
July1st to 15thNight
21%220%34%20%
340
16th to endNight
20%317%33%20%3
376
August1st to 15thNight
25%415%30%21%3
359
16th to endNight
29%217%28%18%3
570
September1st to 15thNight
30%6%22%26%13%
696
16th to endNight
33%7%24%23%11%
673
October1st to 15thNight
37%10%21%21%8%
660
16th to endNight
39%7%17%18%13%3
704
November1st to 15thNight
43%8%20%18%7%1
700
16th to endNight
26%10%23%25%11%2
835
December1st to 15thNight
18%8%25%29%16%2
930
16th to endNight
16%5%23%30%16%6%
992
Page generated at 2017-09-20 04:49:53. Version ac04

Copyright 2017 A. Danko


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