Inukshuk Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Inukshuk Observatory clear sky chart from 2005-11-05 to 2017-09-23.

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
31%
14678
13%
46915
8%
14647
37%
14647
16%
33536

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
17%
720
7%
2506
3%
716
21%
716
7%
2035
January16th to endNight
21%
768
11%
2640
7%
768
27%
768
11%
1987
February1st to 15thNight
19%
703
10%
2287
4%
701
26%
701
11%
1770
February16th to endNight
24%
631
13%
1949
6%
631
33%
631
13%
1464
March1st to 15thNight
20%
720
13%
2100
7%
720
28%
720
15%
1569
March16th to endNight
30%
768
20%
2034
10%
768
37%
768
21%
1413
April1st to 15thNight
25%
718
15%
1796
5%
718
30%
718
20%
1322
April16th to endNight
30%
647
17%
1727
7%
647
37%
647
22%
1210
May1st to 15thNight
35%
360
17%
1440
14%
360
45%
360
16%
950
May16th to endNight
36%
375
13%
1497
10%
374
48%
374
18%
956
June1st to 15thNight
38%
360
9%
1440
9%
360
46%
360
15%
979
June16th to endNight
41%
360
8%
1440
11%
360
46%
360
18%
927
July1st to 15thNight
52%
340
14%
1360
21%
340
58%
340
28%
750
July16th to endNight
55%
376
14%
1418
17%
354
59%
354
26%
806
August1st to 15thNight
52%
440
14%
1511
12%
438
57%
438
24%
951
August16th to endNight
53%
711
20%
1857
10%
711
57%
711
36%
1156
September1st to 15thNight
46%
720
16%
1800
8%
720
49%
720
29%
1241
September16th to endNight
48%
689
23%
1876
15%
689
53%
689
31%
1196
October1st to 15thNight
34%
660
17%
1980
11%
660
43%
660
20%
1377
October16th to endNight
25%
704
11%
2200
6%
704
32%
704
12%
1676
November1st to 15thNight
27%
700
17%
2329
12%
700
35%
700
16%
1645
November16th to endNight
20%
720
10%
2520
6%
720
26%
720
10%
1942
December1st to 15thNight
19%
720
6%
2520
3%
720
23%
720
8%
2039
December16th to endNight
14%
768
9%
2688
4%
768
21%
768
8%
2175

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%8%36%5%35%45%6%33%
47999
Night
17%9%46%5%34446%32%
47084
Cloud CoverDay
18%8%36%5%3445%6%33%
48008
Night
18%9%36%5%34446%32%
47090
TransparencyDay
50%6%12%19%9%1
47686
Night
52%5%11%19%9%
46915
SeeingDay
21%11%28%22%11%4
5500
Night
23%10%29%26%10%
14679

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
21%13%6%9%6%24435%21%
1432
16th to endDay
14%15%48%7%4445%5%25%
1581
February1st to 15thDay
13%13%5%10%7%35%5%4424%
1575
16th to endDay
16%13%46%6%34445%27%
1524
March1st to 15thDay
17%9%47%6%46%5%4428%
1847
16th to endDay
16%7%35%433445%41%
2190
April1st to 15thDay
22%8%35%423346%34%
2152
16th to endDay
20%7%25%5%235%45%37%
2244
May1st to 15thDay
19%7%36%5%3445%6%33%
2511
16th to endDay
17%6%26%5%35%45%7%35%
2618
June1st to 15thDay
20%6%36%5%36%45%6%30%
2520
16th to endDay
17%5%35%6%35%6%6%7%31%
2520
July1st to 15thDay
12%5%245%26%5%6%8%39%
2520
16th to endDay
12%435%5%35%5%7%8%38%
2654
August1st to 15thDay
10%6%25%6%36%5%6%7%38%
2436
16th to endDay
10%5%25%4345%6%8%42%
2333
September1st to 15thDay
15%425%43435%7%42%
2160
16th to endDay
15%4245%24448%44%
1919
October1st to 15thDay
20%6%25%5%3445%6%33%
1650
16th to endDay
26%7%36%7%34335%25%
1670
November1st to 15thDay
16%7%37%5%35%46%6%32%
1527
16th to endDay
23%12%37%5%34445%24%
1440
December1st to 15thDay
22%13%48%8%45%445%17%
1440
16th to endDay
24%15%5%8%6%3333420%
1536
January1st to 15thNight
18%16%6%10%6%45%44419%
2506
16th to endNight
13%16%5%8%6%34347%25%
2640
February1st to 15thNight
13%12%6%11%7%36%445%23%
2285
16th to endNight
17%11%48%6%34446%27%
1949
March1st to 15thNight
19%11%47%6%3333430%
2087
16th to endNight
15%7%35%5%2434441%
2034
April1st to 15thNight
22%8%345%23336%34%
1796
16th to endNight
19%7%25%5%23446%37%
1727
May1st to 15thNight
21%6%44425%45%5%35%
1440
16th to endNight
16%6%35%5%2346%6%38%
1495
June1st to 15thNight
18%6%25%6%35%45%7%32%
1440
16th to endNight
17%426%5%26%5%5%8%36%
1440
July1st to 15thNight
10%324435%5%5%9%46%
1440
16th to endNight
9%4244246%6%7%46%
1514
August1st to 15thNight
10%6%35%5%345%5%10%40%
1521
16th to endNight
9%41443446%5%50%
1857
September1st to 15thNight
14%6%25%43445%5%43%
1800
16th to endNight
15%5%23423345%49%
1876
October1st to 15thNight
20%7%35%42445%6%36%
1980
16th to endNight
25%8%36%5%4435%6%26%
2200
November1st to 15thNight
20%9%36%6%24346%33%
2329
16th to endNight
22%11%49%6%24345%24%
2520
December1st to 15thNight
23%15%47%5%35%5%45%20%
2520
16th to endNight
24%16%5%7%7%3333419%
2688

Percentage Cloud Cover SE (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
21%14%5%10%6%2434421%
1432
16th to endDay
14%14%48%6%45%5%45%25%
1581
February1st to 15thDay
14%13%6%10%7%35%5%4425%
1575
16th to endDay
17%13%46%7%35%445%27%
1524
March1st to 15thDay
20%9%37%6%36%5%4428%
1857
16th to endDay
20%6%35%42344440%
2189
April1st to 15thDay
22%9%45%423345%33%
2152
16th to endDay
20%8%15%42344437%
2244
May1st to 15thDay
24%7%35%5%24446%31%
2511
16th to endDay
23%5%25%5%25%45%6%32%
2618
June1st to 15thDay
20%7%26%5%36%5%46%30%
2520
16th to endDay
16%6%36%6%45%6%6%7%31%
2520
July1st to 15thDay
12%5%245%36%6%6%8%39%
2520
16th to endDay
11%425%5%35%5%7%8%38%
2654
August1st to 15thDay
15%5%25%5%35%46%5%40%
2436
16th to endDay
13%4244345%5%7%43%
2333
September1st to 15thDay
16%425%433447%42%
2160
16th to endDay
15%4235%2445%7%44%
1919
October1st to 15thDay
21%6%35%6%24446%33%
1650
16th to endDay
27%9%37%6%34345%25%
1670
November1st to 15thDay
17%7%46%5%35%45%6%33%
1527
16th to endDay
23%12%47%5%3343426%
1440
December1st to 15thDay
22%14%48%7%46%445%18%
1440
16th to endDay
23%15%49%6%3443320%
1536
January1st to 15thNight
18%15%6%10%6%35%34418%
2506
16th to endNight
14%15%6%7%7%35%346%25%
2640
February1st to 15thNight
13%13%5%11%7%36%445%24%
2278
16th to endNight
17%12%48%6%245%45%28%
1949
March1st to 15thNight
24%10%5%6%5%3333431%
2100
16th to endNight
19%6%45%5%2423341%
2034
April1st to 15thNight
23%8%345%24336%34%
1796
16th to endNight
19%7%26%423446%37%
1727
May1st to 15thNight
24%7%34325%445%34%
1440
16th to endNight
19%6%25%4345%46%37%
1495
June1st to 15thNight
19%6%25%6%35%45%8%31%
1440
16th to endNight
16%5%35%5%25%6%5%8%35%
1440
July1st to 15thNight
10%3145%35%5%5%9%46%
1440
16th to endNight
9%425%425%5%5%8%46%
1514
August1st to 15thNight
12%6%244335%5%9%41%
1521
16th to endNight
11%3145%2445%6%50%
1857
September1st to 15thNight
14%6%35%5%25%346%43%
1800
16th to endNight
15%5%25%323346%48%
1876
October1st to 15thNight
19%8%35%42435%6%36%
1980
16th to endNight
25%9%37%5%34446%26%
2200
November1st to 15thNight
19%9%36%5%24345%34%
2329
16th to endNight
22%11%48%6%24345%25%
2520
December1st to 15thNight
22%15%47%5%35%5%5%420%
2520
16th to endNight
24%15%6%7%7%2433420%
2688

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
66%49%13%5%
1433
16th to endDay
60%6%12%11%7%
1581
February1st to 15thDay
61%6%11%16%3
1577
16th to endDay
58%5%10%14%8%1
1524
March1st to 15thDay
57%6%12%14%7%
1857
16th to endDay
43%6%10%19%14%5%
2190
April1st to 15thDay
52%37%20%12%2
2152
16th to endDay
48%47%19%15%3
2244
May1st to 15thDay
50%6%8%19%13%2
2511
16th to endDay
47%7%11%19%11%1
2622
June1st to 15thDay
52%6%10%20%9%
2520
16th to endDay
48%8%12%19%10%1
2520
July1st to 15thDay
37%8%15%25%11%
2371
16th to endDay
40%9%16%22%10%
2487
August1st to 15thDay
42%9%15%21%9%
2422
16th to endDay
37%6%17%27%10%
2333
September1st to 15thDay
40%7%13%26%11%
2160
16th to endDay
38%7%12%32%9%
1919
October1st to 15thDay
50%5%14%19%8%
1650
16th to endDay
61%6%12%13%6%
1670
November1st to 15thDay
50%6%15%19%8%
1527
16th to endDay
61%5%12%13%5%1
1440
December1st to 15thDay
67%8%11%11%1
1440
16th to endDay
67%5%10%10%5%
1536
January1st to 15thNight
68%5%9%11%5%
2506
16th to endNight
60%5%9%16%7%
2640
February1st to 15thNight
62%410%16%5%
2287
16th to endNight
57%5%9%17%8%
1949
March1st to 15thNight
57%410%19%7%1
2100
16th to endNight
46%49%18%16%4
2034
April1st to 15thNight
52%47%19%15%
1796
16th to endNight
47%5%8%19%16%3
1727
May1st to 15thNight
49%5%7%19%14%4
1440
16th to endNight
44%6%12%20%13%2
1497
June1st to 15thNight
49%6%11%21%9%1
1440
16th to endNight
44%7%12%19%14%
1440
July1st to 15thNight
32%6%14%30%14%
1360
16th to endNight
34%7%16%26%15%
1418
August1st to 15thNight
37%9%16%22%12%
1511
16th to endNight
32%5%17%32%11%
1857
September1st to 15thNight
42%6%11%28%11%1
1800
16th to endNight
37%5%11%34%10%
1876
October1st to 15thNight
48%5%11%22%11%
1980
16th to endNight
59%5%12%16%6%
2200
November1st to 15thNight
52%5%13%17%10%1
2329
16th to endNight
62%5%11%15%4
2520
December1st to 15thNight
65%7%12%12%2
2520
16th to endNight
68%49%12%4
2688

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
31%18%25%21%3
60
16th to endDay
35%15%32%14%2
71
February1st to 15thDay
30%21%35%13%
90
16th to endDay
30%22%22%20%4
183
March1st to 15thDay
25%13%32%22%5%
270
16th to endDay
22%15%28%19%10%2
288
April1st to 15thDay
27%20%26%17%7%1
270
16th to endDay
24%17%24%20%10%3
270
May1st to 15thDay
26%11%29%20%9%3
288
16th to endDay
18%13%34%19%11%1
331
June1st to 15thDay
26%7%31%23%8%2
315
16th to endDay
17%10%33%24%13%1
315
July1st to 15thDay
16%330%30%13%5%
305
16th to endDay
12%5%26%30%18%5%
326
August1st to 15thDay
14%6%25%29%18%6%
313
16th to endDay
11%5%26%27%17%11%
332
September1st to 15thDay
19%6%22%18%20%12%
315
16th to endDay
15%7%26%19%19%12%
283
October1st to 15thDay
23%10%23%25%14%3
255
16th to endDay
33%12%26%20%7%
255
November1st to 15thDay
18%12%32%23%11%2
181
16th to endDay
28%15%33%21%1
60
December1st to 15thDay
20%20%38%18%3
60
16th to endDay
40%18%34%6%
64
January1st to 15thNight
24%17%31%21%4
720
16th to endNight
22%11%35%25%5%
768
February1st to 15thNight
21%13%38%22%4
704
16th to endNight
24%14%32%23%5%
631
March1st to 15thNight
26%13%34%23%2
720
16th to endNight
19%16%25%27%9%
768
April1st to 15thNight
27%12%31%24%4
718
16th to endNight
23%13%27%25%8%
647
May1st to 15thNight
25%6%27%29%9%1
360
16th to endNight
19%6%33%26%13%
375
June1st to 15thNight
21%6%28%34%9%
360
16th to endNight
18%329%34%13%
360
July1st to 15thNight
11%227%43%14%
340
16th to endNight
9%127%43%16%1
376
August1st to 15thNight
14%122%37%22%1
440
16th to endNight
11%423%35%22%2
711
September1st to 15thNight
18%5%24%30%18%2
720
16th to endNight
18%6%22%25%23%2
689
October1st to 15thNight
23%9%27%26%11%1
660
16th to endNight
30%12%24%25%7%
704
November1st to 15thNight
25%10%31%20%11%
700
16th to endNight
29%16%24%20%8%
720
December1st to 15thNight
31%12%31%20%3
720
16th to endNight
33%13%30%18%41
768
Page generated at 2017-09-24 09:15:47. Version ac04

Copyright 2017 A. Danko


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