Cape Dorset
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cape Dorset clear sky chart from 2005-11-06 to 2024-02-05.

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
44%
22808
5%
82333
4%
22727
45%
22727
9%
65107

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
59%
1014
10%
5820
8%
1006
60%
1006
8%
4102
January11th to 20thNight
56%
1028
6%
5616
7%
1010
59%
1010
7%
4396
January21st to endNight
60%
1127
9%
5801
11%
1112
62%
1112
11%
3845
February1st to 10thNight
59%
963
7%
2853
6%
963
60%
963
15%
2169
February11th to 20thNight
63%
819
8%
2571
9%
819
64%
819
13%
1988
February21st to endNight
63%
592
12%
1973
14%
592
64%
592
18%
1391
March1st to 10thNight
54%
720
7%
2267
6%
720
55%
720
12%
1788
March11th to 20thNight
52%
720
10%
2049
5%
720
54%
720
17%
1547
March21st to endNight
51%
792
10%
2030
8%
792
52%
792
17%
1578
April1st to 10thNight
50%
590
7%
1670
6%
590
51%
590
18%
1251
April11th to 20thNight
56%
356
2%
1420
1%
356
56%
356
14%
1027
April21st to endNight
45%
360
0%
1254
0%
360
45%
360
13%
946
May1st to 10thNight
36%
360
0%
1080
0%
360
36%
360
11%
868
May11th to 20thNight
39%
354
0%
831
0%
354
39%
354
16%
679
May21st to endNight
38%
388
0%
776
0%
388
38%
388
16%
663
June1st to 10thNight
47%
135
0%
495
0%
135
47%
135
14%
363
June11th to 20thNight0
0%
36000
0%
194
June21st to endNight0
0%
36000
0%
178
July1st to 10thNight
52%
126
0%
476
0%
126
52%
126
16%
321
July11th to 20thNight
50%
301
0%
649
0%
301
50%
301
21%
517
July21st to endNight
53%
394
0%
846
0%
372
54%
372
25%
642
August1st to 10thNight
49%
358
0%
1028
0%
356
49%
356
17%
772
August11th to 20thNight
44%
356
0%
1183
0%
356
44%
356
15%
885
August21st to endNight
40%
396
2%
1584
1%
396
40%
396
11%
1188
September1st to 10thNight
48%
566
5%
1646
7%
566
48%
566
19%
1212
September11th to 20thNight
32%
720
3%
1800
2%
720
32%
720
11%
1527
September21st to endNight
31%
720
4%
2064
2%
720
32%
720
8%
1777
October1st to 10thNight
22%
720
5%
2182
2%
720
24%
720
6%
1929
October11th to 20thNight
23%
720
2%
2452
2%
720
24%
720
5%
2197
October21st to endNight
29%
837
4%
2862
4%
837
31%
837
7%
2440
November1st to 10thNight
37%
987
6%
2935
4%
987
39%
987
8%
2492
November11th to 20thNight
26%
1040
2%
3175
1%
1040
27%
1040
5%
2861
November21st to endNight
32%
1040
3%
3420
3%
1040
32%
1040
6%
2974
December1st to 10thNight
36%
1040
3%
3448
2%
1040
36%
1040
5%
3083
December11th to 20thNight
39%
1037
5%
4660
5%
1037
40%
1037
4%
3955
December21st to endNight
41%
1132
3%
6697
4%
1116
42%
1116
4%
5362

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
13%11%5%10%8%5%7%6%6%7%21%
76127
Night
8%11%6%11%11%6%9%8%7%7%17%
82779
TransparencyDay
59%9%13%15%4
75736
Night
61%10%12%13%5%
82703
SeeingDay
17%415%26%25%12%
15944
Night
13%415%28%28%12%
22884

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 10thDay
13310%11%6%10%12%12%14%18%
1054
11th to 20thDay
210%7%12%8%7%11%9%8%9%17%
1339
21st to endDay
16%39%7%412%14%8%12%24%
1784
February1st to 10thDay
1447%13%7%11%11%14%10%17%
1199
11th to 20thDay
3411%15%8%12%14%13%9%12%
1279
21st to endDay
2449%10%5%13%12%15%11%14%
1282
March1st to 10thDay
35%412%13%9%10%12%10%7%15%
1690
11th to 20thDay
37%410%8%6%10%10%9%11%21%
1908
21st to endDay
210%6%13%9%6%10%9%8%8%19%
2326
April1st to 10thDay
5%9%5%10%8%6%10%9%7%7%23%
2308
11th to 20thDay
6%10%5%9%10%9%10%7%6%7%19%
2490
21st to endDay
9%14%6%11%10%5%8%5%5%5%22%
2706
May1st to 10thDay
12%15%6%10%11%5%6%5%6%5%19%
2880
11th to 20thDay
11%14%8%14%10%5%6%5%5%5%17%
3064
21st to endDay
12%14%7%14%9%46%5%5%6%19%
3500
June1st to 10thDay
15%13%6%9%6%35%46%7%26%
3460
11th to 20thDay
17%10%5%7%6%45%5%5%7%30%
3600
21st to endDay
14%11%47%6%3445%7%34%
3600
July1st to 10thDay
15%9%46%5%45%5%5%7%35%
3466
11th to 20thDay
21%11%5%8%6%45%45%7%24%
3290
21st to endDay
18%8%36%6%46%5%7%8%28%
3422
August1st to 10thDay
22%10%36%5%45%6%6%8%24%
2906
11th to 20thDay
25%9%36%5%35%45%6%27%
2715
21st to endDay
27%10%46%6%345%6%7%22%
2772
September1st to 10thDay
17%10%5%8%6%46%5%5%6%27%
2296
11th to 20thDay
21%17%6%11%8%45%5%45%15%
2160
21st to endDay
23%19%10%9%6%45%5%45%9%
1893
October1st to 10thDay
21%20%10%13%7%24345%11%
1778
11th to 20thDay
16%17%8%13%8%5%45%5%6%13%
1506
21st to endDay
14%17%8%14%8%5%6%45%6%13%
1494
November1st to 10thDay
6%15%5%18%14%6%6%5%47%15%
1143
11th to 20thDay
9%23%9%18%11%36%43410%
1003
21st to endDay
6%14%10%21%10%6%7%7%7%48%
760
December1st to 10thDay
39%6%19%19%7%10%6%8%6%6%
732
11th to 20thDay
48%6%11%16%9%12%9%6%7%13%
480
21st to endDay
215%314%14%7%12%5%5%5%16%
842
January1st to 10thNight
1339%12%9%13%14%9%10%17%
5903
11th to 20thNight
212%6%11%11%7%10%9%8%8%14%
5638
21st to endNight
15%37%9%7%13%12%9%11%22%
5894
February1st to 10thNight
15%410%11%7%11%13%12%11%14%
2853
11th to 20thNight
1449%14%9%13%11%12%9%15%
2568
21st to endNight
25%38%12%6%10%11%14%11%17%
1973
March1st to 10thNight
15%413%13%9%11%12%11%9%12%
2257
11th to 20thNight
27%412%11%7%9%8%8%11%20%
2048
21st to endNight
211%7%10%10%6%10%7%7%7%23%
2030
April1st to 10thNight
5%9%410%9%6%9%9%8%7%25%
1670
11th to 20thNight
7%10%38%8%8%11%7%7%6%27%
1420
21st to endNight
8%12%5%9%10%7%6%7%47%24%
1254
May1st to 10thNight
12%12%5%12%11%46%6%6%7%18%
1080
11th to 20thNight
10%16%6%13%7%5%4445%25%
830
21st to endNight
12%14%5%15%9%46%5%5%5%21%
776
June1st to 10thNight
18%11%6%5%5%5%35%7%8%26%
495
11th to 20thNight
18%10%27%43436%6%37%
360
21st to endNight
14%9%35%45%5%5%5%11%35%
360
July1st to 10thNight
14%10%5%8%5%435%6%8%33%
491
11th to 20thNight
18%11%38%5%45%5%38%30%
670
21st to endNight
19%6%36%6%35%5%7%8%31%
896
August1st to 10thNight
23%9%45%5%35%5%5%6%30%
1033
11th to 20thNight
24%8%37%5%3445%7%29%
1183
21st to endNight
26%12%35%5%345%46%27%
1584
September1st to 10thNight
18%11%37%6%446%5%7%30%
1646
11th to 20thNight
20%17%7%9%8%4444419%
1800
21st to endNight
24%14%8%8%7%45%45%6%14%
2064
October1st to 10thNight
20%19%8%13%6%45%44412%
2182
11th to 20thNight
18%19%11%15%7%45%44410%
2452
21st to endNight
15%18%7%14%8%45%445%15%
2862
November1st to 10thNight
7%14%6%16%14%5%6%6%5%5%15%
2935
11th to 20thNight
12%19%8%16%13%5%5%5%3410%
3175
21st to endNight
8%15%10%17%12%5%8%5%6%7%9%
3420
December1st to 10thNight
413%6%17%16%7%10%8%8%46%
3448
11th to 20thNight
5%9%5%12%15%9%13%9%6%6%10%
4715
21st to endNight
413%7%16%12%8%9%6%6%5%14%
6814

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
46%11%13%19%8%2
1054
11th to 20thDay
58%15%15%12%1
1339
21st to endDay
46%9%13%17%15%
1784
February1st to 10thDay
50%10%18%16%6%
1199
11th to 20thDay
55%11%17%14%4
1286
21st to endDay
48%12%15%15%10%1
1282
March1st to 10thDay
59%10%10%16%5%
1693
11th to 20thDay
50%9%12%20%8%
1908
21st to endDay
55%9%11%17%7%1
2326
April1st to 10thDay
54%9%11%17%8%1
2308
11th to 20thDay
58%9%9%16%7%
2490
21st to endDay
63%7%9%12%8%1
2706
May1st to 10thDay
64%8%11%14%4
2880
11th to 20thDay
68%7%10%11%4
3068
21st to endDay
66%7%13%12%2
3500
June1st to 10thDay
56%7%16%17%4
3460
11th to 20thDay
53%7%14%21%5%
3600
21st to endDay
50%6%17%23%4
3600
July1st to 10thDay
47%9%14%23%7%
3372
11th to 20thDay
57%10%16%16%2
3188
21st to endDay
48%11%21%18%2
3232
August1st to 10thDay
56%10%19%14%
2887
11th to 20thDay
56%10%16%13%5%
2715
21st to endDay
60%9%16%14%1
2772
September1st to 10thDay
56%9%16%16%2
2296
11th to 20thDay
70%10%11%9%1
2160
21st to endDay
75%8%9%6%1
1893
October1st to 10thDay
76%6%9%8%1
1778
11th to 20thDay
71%9%9%9%2
1506
21st to endDay
69%11%11%8%1
1494
November1st to 10thDay
66%11%12%9%1
1143
11th to 20thDay
76%10%8%6%
1003
21st to endDay
72%12%10%5%1
760
December1st to 10thDay
70%14%7%8%2
732
11th to 20thDay
60%17%9%14%
480
21st to endDay
63%10%11%6%8%1
842
January1st to 10thNight
51%13%13%15%6%3
5903
11th to 20thNight
61%11%15%11%1
5638
21st to endNight
48%9%10%14%17%1
5894
February1st to 10thNight
54%11%15%15%6%
2853
11th to 20thNight
56%11%15%14%4
2571
21st to endNight
48%9%15%17%10%1
1973
March1st to 10thNight
58%11%12%14%5%
2267
11th to 20thNight
55%8%12%17%9%
2049
21st to endNight
57%7%9%20%5%1
2030
April1st to 10thNight
52%9%9%19%10%1
1670
11th to 20thNight
54%8%10%18%9%1
1420
21st to endNight
58%7%9%18%7%1
1254
May1st to 10thNight
63%8%10%16%3
1080
11th to 20thNight
61%6%13%14%6%
831
21st to endNight
65%6%12%13%4
776
June1st to 10thNight
55%8%13%19%5%
495
11th to 20thNight
46%8%11%28%7%
360
21st to endNight
44%6%18%25%8%
360
July1st to 10thNight
45%11%13%23%8%
476
11th to 20thNight
55%8%16%19%2
649
21st to endNight
46%11%17%23%3
846
August1st to 10thNight
53%10%19%17%2
1028
11th to 20thNight
56%7%15%18%3
1183
21st to endNight
57%10%16%16%2
1584
September1st to 10thNight
51%8%17%22%1
1646
11th to 20thNight
67%8%13%11%1
1800
21st to endNight
69%10%11%10%
2064
October1st to 10thNight
75%8%8%8%1
2182
11th to 20thNight
77%8%8%6%1
2452
21st to endNight
69%10%10%9%2
2862
November1st to 10thNight
69%9%11%10%2
2935
11th to 20thNight
75%10%8%7%1
3175
21st to endNight
71%11%11%7%1
3420
December1st to 10thNight
71%14%8%6%1
3448
11th to 20thNight
65%15%8%10%1
4715
21st to endNight
65%10%10%7%6%1
6814

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
212%33%23%30%
117
11th to 20thDay
3420%31%29%13%
180
21st to endDay
6%39%29%35%19%
198
February1st to 10thDay
2111%26%35%25%
168
11th to 20thDay
18%21%44%26%
160
21st to endDay
2111%24%36%27%
176
March1st to 10thDay
4416%25%27%24%
313
11th to 20thDay
4315%27%33%18%
420
21st to endDay
7%414%32%27%16%
462
April1st to 10thDay
10%5%17%24%26%18%
420
11th to 20thDay
10%211%26%28%23%
412
21st to endDay
15%6%19%31%20%10%
606
May1st to 10thDay
19%416%27%22%11%
783
11th to 20thDay
17%6%15%26%24%11%
802
21st to endDay
15%414%28%26%12%
874
June1st to 10thDay
19%415%26%23%14%
810
11th to 20thDay
18%411%26%27%14%
810
21st to endDay
18%414%30%24%10%
810
July1st to 10thDay
19%315%26%29%8%
796
11th to 20thDay
26%5%12%26%23%10%
792
21st to endDay
19%410%23%34%10%
881
August1st to 10thDay
23%313%24%26%10%
805
11th to 20thDay
27%414%26%22%7%
673
21st to endDay
30%6%13%22%20%9%
495
September1st to 10thDay
20%5%16%21%26%13%
450
11th to 20thDay
28%6%18%20%22%7%
450
21st to endDay
30%7%20%23%16%4
450
October1st to 10thDay
29%7%17%26%17%4
439
11th to 20thDay
16%5%21%28%21%9%
246
21st to endDay
19%5%20%20%21%16%
198
November1st to 10thDay
8%5%16%23%34%14%
180
11th to 20thDay
17%7%21%25%20%11%
180
21st to endDay
12%8%20%27%21%13%
180
December1st to 10thDay
9%5%17%26%33%10%
167
21st to endDay
10%5%15%39%22%10%
41
January1st to 10thNight
4110%30%34%22%
1040
11th to 20thNight
4414%31%30%16%
1040
21st to endNight
4312%29%34%19%
1144
February1st to 10thNight
3213%29%34%20%
963
11th to 20thNight
18%24%43%22%
824
21st to endNight
4211%30%34%20%
592
March1st to 10thNight
4214%29%31%20%
720
11th to 20thNight
6%318%29%31%13%
720
21st to endNight
6%315%33%32%12%
792
April1st to 10thNight
8%420%30%28%10%
590
11th to 20thNight
10%314%30%32%11%
356
21st to endNight
13%419%33%22%9%
360
May1st to 10thNight
18%415%33%23%7%
360
11th to 20thNight
16%5%17%34%21%8%
354
21st to endNight
18%414%31%27%7%
389
June1st to 10thNight
21%215%31%22%9%
135
July1st to 10thNight
21%410%29%30%6%
126
11th to 20thNight
22%39%26%34%7%
301
21st to endNight
21%28%25%38%5%
394
August1st to 10thNight
26%48%26%30%7%
358
11th to 20thNight
26%415%25%26%4
356
21st to endNight
31%416%22%22%5%
396
September1st to 10thNight
21%416%28%25%7%
566
11th to 20thNight
26%5%16%28%21%5%
720
21st to endNight
28%6%17%26%18%4
720
October1st to 10thNight
26%6%22%25%18%4
720
11th to 20thNight
27%6%17%24%20%6%
720
21st to endNight
23%5%17%21%23%10%
837
November1st to 10thNight
13%5%15%28%27%12%
987
11th to 20thNight
18%5%19%27%21%9%
1040
21st to endNight
14%5%17%24%29%12%
1040
December1st to 10thNight
10%318%25%30%14%
1040
11th to 20thNight
10%418%31%25%12%
1040
21st to endNight
8%417%25%32%13%
1144
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