Inukshuk Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Inukshuk Observatory clear sky chart from 2005-11-06 to 2024-01-17.

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
29%
24904
13%
74752
7%
24843
35%
24843
17%
54018

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 10thNight
17%
950
9%
2648
3%
946
23%
946
13%
2063
January11th to 20thNight
15%
935
8%
2617
3%
935
19%
935
10%
2150
January21st to endNight
16%
990
7%
2772
2%
990
21%
990
11%
2245
February1st to 10thNight
19%
900
12%
2358
2%
900
26%
900
16%
1809
February11th to 20thNight
21%
816
16%
2211
5%
812
29%
812
15%
1640
February21st to endNight
16%
592
12%
1776
3%
592
25%
592
13%
1357
March1st to 10thNight
28%
720
16%
2160
9%
720
35%
720
19%
1495
March11th to 20thNight
27%
641
18%
2081
11%
641
36%
641
19%
1376
March21st to endNight
31%
594
17%
2003
14%
594
37%
594
16%
1391
April1st to 10thNight
23%
540
12%
1800
7%
540
33%
540
15%
1305
April11th to 20thNight
31%
533
16%
1775
11%
533
40%
533
17%
1232
April21st to endNight
32%
540
13%
1670
8%
540
37%
540
18%
1190
May1st to 10thNight
27%
540
12%
1448
6%
540
32%
540
19%
1064
May11th to 20thNight
33%
531
17%
1417
9%
531
39%
531
23%
1011
May21st to endNight
44%
583
11%
1552
6%
582
48%
582
26%
1049
June1st to 10thNight
43%
540
12%
1440
5%
540
47%
540
30%
936
June11th to 20thNight
38%
540
11%
1440
5%
540
41%
540
27%
981
June21st to endNight
48%
540
13%
1440
6%
540
51%
540
31%
940
July1st to 10thNight
57%
525
15%
1400
8%
525
59%
525
42%
825
July11th to 20thNight
48%
522
15%
1392
7%
522
51%
522
34%
867
July21st to endNight
57%
591
20%
1487
11%
558
61%
558
40%
886
August1st to 10thNight
58%
537
20%
1423
13%
534
62%
534
34%
899
August11th to 20thNight
55%
534
20%
1590
16%
534
61%
534
30%
993
August21st to endNight
49%
594
17%
1980
17%
594
52%
594
28%
1180
September1st to 10thNight
48%
540
20%
1800
18%
540
54%
540
29%
1061
September11th to 20thNight
46%
576
22%
1836
18%
576
54%
576
29%
1110
September21st to endNight
35%
720
14%
1980
9%
720
39%
720
24%
1368
October1st to 10thNight
33%
720
18%
2132
11%
720
39%
720
23%
1409
October11th to 20thNight
25%
720
13%
2181
6%
720
32%
720
15%
1603
October21st to endNight
25%
792
10%
2574
5%
792
31%
792
12%
1951
November1st to 10thNight
23%
740
15%
2406
8%
740
33%
740
17%
1678
November11th to 20thNight
16%
878
11%
2588
4%
878
23%
878
11%
2030
November21st to endNight
18%
950
10%
2660
5%
950
22%
950
12%
2140
December1st to 10thNight
16%
950
6%
2660
1%
950
20%
950
11%
2134
December11th to 20thNight
14%
949
8%
3234
1%
948
19%
948
8%
2623
December21st to endNight
10%
1041
6%
4821
2%
1026
17%
1026
4%
4027

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
14%10%48%7%45%5%5%7%31%
74814
Night
14%11%5%8%6%45%5%5%6%32%
75042
TransparencyDay
52%6%12%20%9%1
74514
Night
52%6%12%20%9%1
74862
SeeingDay
20%16%32%20%9%3
14882
Night
19%12%32%26%9%1
24910

By Month

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 10thDay
11%11%8%12%10%5%6%5%6%7%19%
1517
11th to 20thDay
12%17%8%13%10%47%5%48%13%
1488
21st to endDay
12%13%8%14%9%45%5%6%8%16%
1584
February1st to 10thDay
8%13%5%10%7%48%7%6%7%25%
1598
11th to 20thDay
9%11%5%10%8%47%6%6%7%28%
1637
21st to endDay
13%12%7%11%9%46%5%5%6%23%
1480
March1st to 10thDay
12%11%49%8%46%5%6%7%30%
1800
11th to 20thDay
12%9%5%9%6%44446%36%
1894
21st to endDay
16%11%6%8%8%5%5%5%45%27%
2353
April1st to 10thDay
15%13%5%8%6%36%5%5%8%26%
2160
11th to 20thDay
20%11%5%8%6%34445%30%
2134
21st to endDay
18%11%37%5%45%5%5%6%30%
2288
May1st to 10thDay
17%10%37%6%345%5%7%32%
2510
11th to 20thDay
15%10%38%6%35%5%5%6%34%
2479
21st to endDay
13%7%37%6%45%5%6%8%36%
2725
June1st to 10thDay
14%7%35%5%3446%9%41%
2520
11th to 20thDay
14%6%36%6%46%46%7%37%
2520
21st to endDay
12%7%35%5%35%6%6%10%37%
2520
July1st to 10thDay
7%325%5%35%5%7%11%45%
2520
11th to 20thDay
11%5%26%5%446%6%8%43%
2520
21st to endDay
9%425%5%45%6%6%8%45%
2743
August1st to 10thDay
11%5%36%6%36%6%6%9%40%
2507
11th to 20thDay
14%6%35%5%345%6%6%42%
2309
21st to endDay
15%6%25%6%3445%7%42%
2376
September1st to 10thDay
16%7%35%5%3446%7%42%
2160
11th to 20thDay
15%6%36%6%446%5%8%38%
2106
21st to endDay
17%10%46%6%35%45%8%32%
1980
October1st to 10thDay
18%10%37%5%346%5%8%32%
1823
11th to 20thDay
21%13%5%8%7%36%446%22%
1778
21st to endDay
22%15%5%7%6%33346%25%
1782
November1st to 10thDay
15%15%5%6%6%35%5%5%5%31%
1672
11th to 20thDay
16%16%6%13%7%45%445%20%
1590
21st to endDay
15%13%7%12%9%46%6%5%5%19%
1520
December1st to 10thDay
12%13%8%14%10%5%6%5%5%5%18%
1520
11th to 20thDay
14%14%7%12%13%5%5%5%5%5%16%
1918
21st to endDay
19%23%7%12%7%4433414%
2783
January1st to 10thNight
11%12%5%12%9%5%6%5%6%7%22%
2648
11th to 20thNight
12%14%6%14%9%5%6%5%6%6%18%
2617
21st to endNight
12%13%8%12%9%5%5%6%5%6%19%
2772
February1st to 10thNight
8%10%6%13%9%5%6%5%5%7%26%
2358
11th to 20thNight
9%11%49%7%5%8%47%7%29%
2210
21st to endNight
13%14%7%9%8%45%5%5%5%24%
1776
March1st to 10thNight
11%9%5%8%6%45%5%5%7%36%
2160
11th to 20thNight
12%11%47%6%3445%6%39%
2081
21st to endNight
15%10%47%6%35%45%6%34%
2003
April1st to 10thNight
19%10%6%9%5%2446%6%30%
1800
11th to 20thNight
22%9%46%42445%7%34%
1775
21st to endNight
17%9%47%6%45%5%5%6%33%
1670
May1st to 10thNight
19%10%37%7%345%5%6%31%
1448
11th to 20thNight
16%7%37%6%35%45%6%37%
1416
21st to endNight
12%6%25%6%35%6%5%9%40%
1551
June1st to 10thNight
11%7%445%25%45%7%46%
1440
11th to 20thNight
13%6%35%7%45%5%5%7%40%
1440
21st to endNight
12%5%235%45%5%6%10%42%
1440
July1st to 10thNight
9%314425%45%9%55%
1440
11th to 20thNight
10%5%23435%5%7%8%47%
1440
21st to endNight
7%314435%5%6%7%55%
1575
August1st to 10thNight
9%4245%36%6%6%8%47%
1432
11th to 20thNight
12%6%25%435%45%7%49%
1590
21st to endNight
13%7%25%433347%49%
1980
September1st to 10thNight
12%6%2443445%7%49%
1800
11th to 20thNight
11%6%24435%5%5%7%47%
1836
21st to endNight
16%9%36%6%34448%37%
1980
October1st to 10thNight
16%7%25%6%345%6%6%40%
2132
11th to 20thNight
18%12%5%6%6%345%5%6%29%
2181
21st to endNight
18%13%48%7%45%46%7%24%
2574
November1st to 10thNight
16%12%5%6%5%3446%7%32%
2406
11th to 20thNight
14%14%7%11%7%35%445%24%
2588
21st to endNight
14%13%6%13%8%45%5%5%6%21%
2660
December1st to 10thNight
11%15%7%12%9%5%5%45%6%20%
2660
11th to 20thNight
11%15%7%13%10%46%5%5%5%18%
3279
21st to endNight
23%21%7%10%6%3344415%
4884

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 10thDay
63%412%15%6%
1518
11th to 20thDay
71%5%7%10%7%
1488
21st to endDay
66%412%11%7%1
1584
February1st to 10thDay
56%5%10%18%9%
1598
11th to 20thDay
55%5%12%21%7%
1646
21st to endDay
62%5%10%14%9%1
1480
March1st to 10thDay
54%5%15%15%11%1
1800
11th to 20thDay
51%413%20%11%1
1894
21st to endDay
60%411%17%7%1
2353
April1st to 10thDay
57%6%11%17%9%1
2160
11th to 20thDay
58%47%21%9%1
2134
21st to endDay
54%5%10%18%12%1
2288
May1st to 10thDay
51%6%11%21%10%1
2510
11th to 20thDay
50%6%10%21%11%2
2483
21st to endDay
46%7%11%22%12%1
2725
June1st to 10thDay
40%6%15%26%12%1
2520
11th to 20thDay
46%6%13%22%14%1
2520
21st to endDay
41%8%16%24%9%1
2520
July1st to 10thDay
32%7%14%33%14%1
2451
11th to 20thDay
36%8%13%27%13%2
2445
21st to endDay
34%8%15%25%17%1
2591
August1st to 10thDay
39%7%15%28%9%2
2492
11th to 20thDay
40%8%14%26%12%
2309
21st to endDay
41%6%13%23%15%1
2376
September1st to 10thDay
42%5%13%28%12%
2160
11th to 20thDay
44%6%19%23%7%
2106
21st to endDay
51%5%12%25%7%
1980
October1st to 10thDay
49%6%13%23%8%
1823
11th to 20thDay
63%5%10%15%6%
1778
21st to endDay
62%5%10%17%5%
1782
November1st to 10thDay
55%5%12%19%8%1
1672
11th to 20thDay
68%410%12%6%
1590
21st to endDay
66%6%14%11%31
1520
December1st to 10thDay
67%6%10%14%4
1520
11th to 20thDay
70%6%10%10%4
1915
21st to endDay
76%45%10%4
2783
January1st to 10thNight
60%5%12%17%41
2648
11th to 20thNight
67%6%9%13%5%
2617
21st to endNight
65%5%9%14%6%1
2772
February1st to 10thNight
57%5%8%18%10%1
2358
11th to 20thNight
54%6%12%20%8%1
2211
21st to endNight
61%411%16%7%1
1776
March1st to 10thNight
49%5%13%21%11%1
2160
11th to 20thNight
46%5%13%22%12%1
2081
21st to endNight
50%6%11%19%12%2
2003
April1st to 10thNight
55%5%9%17%14%1
1800
11th to 20thNight
52%49%20%12%2
1775
21st to endNight
51%7%10%18%14%1
1670
May1st to 10thNight
53%6%12%18%10%2
1448
11th to 20thNight
48%6%9%24%12%2
1417
21st to endNight
40%8%16%22%12%2
1552
June1st to 10thNight
36%8%15%28%12%
1440
11th to 20thNight
44%5%14%21%15%1
1440
21st to endNight
36%7%17%29%10%2
1440
July1st to 10thNight
29%5%15%33%18%
1400
11th to 20thNight
32%8%16%29%13%2
1392
21st to endNight
28%7%16%32%14%3
1487
August1st to 10thNight
33%8%14%30%13%2
1423
11th to 20thNight
36%7%13%28%14%2
1590
21st to endNight
37%6%13%26%16%3
1980
September1st to 10thNight
35%6%13%31%14%1
1800
11th to 20thNight
36%6%16%33%8%
1836
21st to endNight
46%6%15%25%8%
1980
October1st to 10thNight
43%6%13%28%9%1
2132
11th to 20thNight
55%5%13%19%7%1
2181
21st to endNight
60%6%13%16%6%
2574
November1st to 10thNight
51%5%14%20%10%
2406
11th to 20thNight
62%5%12%13%7%1
2588
21st to endNight
64%5%14%13%31
2660
December1st to 10thNight
64%5%14%14%3
2660
11th to 20thNight
66%6%10%13%4
3281
21st to endNight
73%46%12%4
4884

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 10thDay
22%17%31%23%5%1
270
11th to 20thDay
24%18%36%18%4
258
21st to endDay
25%14%41%16%3
264
February1st to 10thDay
18%27%40%13%3
240
11th to 20thDay
22%26%38%12%3
240
21st to endDay
26%23%44%6%1
198
March1st to 10thDay
19%25%38%15%3
240
11th to 20thDay
23%22%31%17%5%1
240
21st to endDay
25%19%31%15%8%3
439
April1st to 10thDay
27%15%32%20%41
420
11th to 20thDay
29%18%27%19%5%1
412
21st to endDay
28%17%27%20%6%1
420
May1st to 10thDay
22%22%30%19%6%2
593
11th to 20thDay
22%18%31%19%8%3
625
21st to endDay
18%16%32%21%11%3
679
June1st to 10thDay
14%17%33%23%8%4
630
11th to 20thDay
16%14%35%24%8%3
630
21st to endDay
15%12%33%23%14%4
630
July1st to 10thDay
7%8%34%28%15%8%
621
11th to 20thDay
13%12%31%25%14%5%
618
21st to endDay
10%8%33%30%13%7%
684
August1st to 10thDay
13%8%27%28%19%5%
626
11th to 20thDay
17%7%23%27%21%5%
553
21st to endDay
20%9%26%23%16%6%
495
September1st to 10thDay
20%13%22%26%14%4
450
11th to 20thDay
15%10%33%28%11%3
450
21st to endDay
24%17%27%20%8%3
450
October1st to 10thDay
23%15%31%20%10%2
293
11th to 20thDay
27%24%32%14%3
270
21st to endDay
35%24%31%8%2
297
November1st to 10thDay
24%18%38%16%41
270
11th to 20thDay
26%26%34%9%41
270
21st to endDay
24%23%40%9%4
270
December1st to 10thDay
21%17%42%13%6%
270
11th to 20thDay
28%25%34%11%2
270
21st to endDay
29%26%32%11%2
297
January1st to 10thNight
18%16%39%22%5%
950
11th to 20thNight
21%13%39%20%6%1
935
21st to endNight
20%11%41%23%6%
990
February1st to 10thNight
14%17%39%24%6%
900
11th to 20thNight
17%18%37%23%6%
816
21st to endNight
21%15%40%22%3
592
March1st to 10thNight
17%16%34%25%8%1
720
11th to 20thNight
18%15%36%25%6%
641
21st to endNight
20%12%30%27%10%1
594
April1st to 10thNight
24%13%34%23%6%1
540
11th to 20thNight
28%11%27%27%7%
533
21st to endNight
23%11%29%28%9%1
540
May1st to 10thNight
23%12%31%27%6%1
540
11th to 20thNight
20%9%33%29%8%1
531
21st to endNight
17%7%27%36%13%
584
June1st to 10thNight
13%10%29%36%11%1
540
11th to 20thNight
18%6%31%34%11%
540
21st to endNight
15%5%24%40%14%2
540
July1st to 10thNight
9%424%38%25%1
525
11th to 20thNight
12%7%28%31%20%1
522
21st to endNight
8%326%39%21%3
591
August1st to 10thNight
10%321%44%20%2
537
11th to 20thNight
15%219%34%28%3
534
21st to endNight
16%6%24%33%19%2
594
September1st to 10thNight
16%6%26%32%18%3
540
11th to 20thNight
14%7%30%31%16%2
576
21st to endNight
20%11%28%28%12%1
720
October1st to 10thNight
22%10%28%26%13%1
720
11th to 20thNight
24%17%29%24%7%
720
21st to endNight
26%11%32%23%7%1
792
November1st to 10thNight
25%11%35%23%6%1
740
11th to 20thNight
20%19%35%21%5%
878
21st to endNight
23%19%34%21%4
950
December1st to 10thNight
22%15%38%19%6%
950
11th to 20thNight
20%17%36%20%6%1
950
21st to endNight
28%16%33%19%3
1045
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