Atikokan
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Atikokan 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
29%
25138
10%
80537
6%
25041
34%
25041
15%
60538

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
22%
943
8%
4712
4%
926
28%
926
7%
3613
January11th to 20thNight
20%
944
5%
4493
4%
930
24%
930
6%
3733
January21st to endNight
17%
1036
5%
4877
3%
1023
22%
1023
6%
4032
February1st to 10thNight
25%
923
10%
2404
3%
923
30%
923
16%
1860
February11th to 20thNight
30%
879
15%
2274
7%
875
35%
875
20%
1672
February21st to endNight
26%
670
13%
1854
5%
670
32%
670
14%
1428
March1st to 10thNight
25%
718
14%
2160
8%
718
30%
718
15%
1603
March11th to 20thNight
26%
540
16%
1980
9%
540
38%
540
16%
1333
March21st to endNight
32%
594
17%
2080
13%
594
40%
594
17%
1417
April1st to 10thNight
28%
540
14%
1800
10%
540
37%
540
17%
1259
April11th to 20thNight
29%
533
13%
1760
8%
533
37%
533
17%
1246
April21st to endNight
35%
540
13%
1526
8%
540
39%
540
20%
1095
May1st to 10thNight
29%
540
13%
1440
6%
540
34%
540
20%
1049
May11th to 20thNight
36%
531
13%
1416
6%
531
40%
531
25%
984
May21st to endNight
39%
584
10%
1552
5%
582
42%
582
26%
1074
June1st to 10thNight
40%
540
7%
1347
4%
540
43%
540
27%
941
June11th to 20thNight
41%
540
8%
1260
4%
540
45%
540
31%
865
June21st to endNight
47%
540
7%
1260
5%
540
48%
540
28%
901
July1st to 10thNight
52%
525
11%
1225
7%
525
54%
525
42%
782
July11th to 20thNight
45%
522
12%
1290
5%
522
48%
522
36%
830
July21st to endNight
53%
591
15%
1487
7%
558
54%
558
34%
942
August1st to 10thNight
50%
537
17%
1423
8%
534
54%
534
36%
899
August11th to 20thNight
50%
534
17%
1562
11%
534
56%
534
27%
999
August21st to endNight
45%
594
16%
1894
14%
594
50%
594
27%
1179
September1st to 10thNight
45%
540
16%
1800
15%
540
51%
540
26%
1113
September11th to 20thNight
40%
540
15%
1800
13%
540
47%
540
23%
1158
September21st to endNight
31%
670
15%
2038
11%
670
36%
670
18%
1441
October1st to 10thNight
27%
720
13%
2160
7%
720
32%
720
17%
1601
October11th to 20thNight
24%
720
13%
2160
6%
720
29%
720
15%
1604
October21st to endNight
21%
792
9%
2550
4%
792
26%
792
11%
2003
November1st to 10thNight
21%
882
10%
2548
5%
882
25%
882
12%
2012
November11th to 20thNight
16%
950
7%
2660
3%
950
20%
950
8%
2258
November21st to endNight
14%
950
6%
2660
2%
950
17%
950
8%
2271
December1st to 10thNight
17%
950
6%
2660
2%
950
20%
950
7%
2294
December11th to 20thNight
16%
949
8%
3260
3%
949
20%
949
6%
2628
December21st to endNight
13%
1037
4%
5165
2%
1026
17%
1026
3%
4419

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
15%11%5%8%7%45%5%5%7%30%
78031
Night
14%12%5%9%7%45%5%5%6%28%
80861
TransparencyDay
53%6%12%20%8%1
77726
Night
57%6%12%18%7%1
80700
SeeingDay
20%14%33%22%9%2
15077
Night
20%11%32%26%10%1
25171

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
8%15%7%15%11%5%6%5%5%5%17%
2218
11th to 20thDay
6%10%6%14%10%6%9%9%7%5%18%
2465
21st to endDay
9%16%14%19%9%5%5%5%5%49%
2783
February1st to 10thDay
8%11%5%10%8%5%8%9%7%5%23%
1649
11th to 20thDay
9%10%5%11%10%5%5%5%6%6%29%
1574
21st to endDay
7%12%7%11%9%45%5%6%6%29%
1401
March1st to 10thDay
8%11%5%10%7%46%45%6%32%
1814
11th to 20thDay
11%14%6%9%7%34345%32%
1980
21st to endDay
14%11%48%7%35%45%6%32%
2276
April1st to 10thDay
15%13%48%7%35%5%5%7%29%
2160
11th to 20thDay
18%11%47%5%3345%7%33%
2146
21st to endDay
17%12%47%6%44445%33%
2434
May1st to 10thDay
18%12%46%7%3445%6%30%
2520
11th to 20thDay
17%10%46%6%45%45%7%32%
2479
21st to endDay
21%6%35%435%5%5%8%36%
2725
June1st to 10thDay
17%7%35%5%35%5%6%8%36%
2610
11th to 20thDay
17%6%36%5%35%5%5%7%37%
2700
21st to endDay
17%6%25%6%36%5%6%9%34%
2700
July1st to 10thDay
10%5%25%5%35%6%6%9%45%
2700
11th to 20thDay
15%5%25%5%36%5%6%9%38%
2626
21st to endDay
12%6%35%6%35%6%6%8%42%
2743
August1st to 10thDay
11%6%37%6%35%5%7%8%39%
2507
11th to 20thDay
15%5%245%45%5%7%9%41%
2335
21st to endDay
16%6%25%5%45%45%8%40%
2462
September1st to 10thDay
16%6%36%5%3445%8%39%
2160
11th to 20thDay
18%9%36%6%345%6%8%33%
2160
21st to endDay
23%9%37%5%35%45%6%31%
1900
October1st to 10thDay
18%13%37%7%3445%7%28%
1800
11th to 20thDay
19%16%6%8%6%35%446%22%
1800
21st to endDay
21%20%5%9%5%3333424%
1805
November1st to 10thDay
16%18%8%8%6%45%445%21%
1528
11th to 20thDay
16%17%8%14%9%4433418%
1520
21st to endDay
16%17%6%16%9%44435%16%
1520
December1st to 10thDay
9%16%6%16%12%5%8%5%5%415%
1520
11th to 20thDay
12%16%8%12%9%45%5%45%20%
1869
21st to endDay
21%22%8%9%8%2333415%
2442
January1st to 10thNight
8%16%7%14%11%5%5%6%6%6%19%
4737
11th to 20thNight
7%11%6%14%14%8%10%8%4415%
4502
21st to endNight
9%17%14%16%7%35%5%45%14%
4884
February1st to 10thNight
8%11%6%10%8%5%10%6%7%7%24%
2404
11th to 20thNight
9%10%410%8%47%7%6%6%31%
2273
21st to endNight
6%14%7%11%9%5%6%5%5%5%26%
1854
March1st to 10thNight
9%12%5%9%9%5%6%5%46%29%
2149
11th to 20thNight
11%12%49%7%35%446%36%
1979
21st to endNight
16%10%48%6%4445%8%32%
2080
April1st to 10thNight
17%11%47%5%345%47%33%
1800
11th to 20thNight
16%13%5%7%5%3445%7%32%
1760
21st to endNight
19%11%46%5%35%5%5%6%32%
1526
May1st to 10thNight
17%11%37%6%36%5%5%6%33%
1440
11th to 20thNight
18%8%445%4445%6%38%
1416
21st to endNight
19%7%345%245%47%41%
1551
June1st to 10thNight
19%6%25%5%3445%8%40%
1347
11th to 20thNight
13%425%5%345%6%9%43%
1260
21st to endNight
13%5%26%5%36%5%6%8%41%
1260
July1st to 10thNight
9%5%2443446%10%50%
1260
11th to 20thNight
10%3245%35%5%6%9%48%
1332
21st to endNight
8%5%25%435%5%5%7%51%
1575
August1st to 10thNight
8%6%35%5%25%5%5%10%47%
1432
11th to 20thNight
12%5%26%5%335%5%7%46%
1562
21st to endNight
15%5%2443445%7%45%
1894
September1st to 10thNight
13%6%26%6%3445%7%45%
1800
11th to 20thNight
17%7%35%433445%45%
1800
21st to endNight
23%10%35%42435%7%35%
2038
October1st to 10thNight
20%12%35%5%44447%32%
2160
11th to 20thNight
19%14%5%6%6%245%46%29%
2160
21st to endNight
19%14%5%10%7%3346%6%23%
2550
November1st to 10thNight
16%16%6%10%7%3435%5%24%
2548
11th to 20thNight
17%15%7%14%8%35%44418%
2660
21st to endNight
13%17%8%13%10%45%44417%
2660
December1st to 10thNight
9%15%7%15%12%6%6%5%45%15%
2660
11th to 20thNight
12%14%7%13%9%5%5%6%6%6%17%
3323
21st to endNight
22%21%7%12%8%3443313%
5225

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
68%5%7%13%6%
2219
11th to 20thDay
65%5%9%19%3
2465
21st to endDay
78%45%9%4
2783
February1st to 10thDay
58%5%11%16%9%1
1649
11th to 20thDay
55%410%20%9%1
1583
21st to endDay
55%411%16%12%1
1401
March1st to 10thDay
52%6%13%18%11%1
1816
11th to 20thDay
54%5%11%18%11%1
1980
21st to endDay
53%7%12%15%12%2
2276
April1st to 10thDay
55%5%8%18%13%2
2160
11th to 20thDay
51%5%11%19%12%1
2146
21st to endDay
54%5%8%19%13%1
2434
May1st to 10thDay
53%6%11%21%7%1
2520
11th to 20thDay
49%6%13%21%10%1
2483
21st to endDay
47%7%13%21%12%1
2725
June1st to 10thDay
44%7%15%24%9%1
2610
11th to 20thDay
45%7%12%23%13%1
2700
21st to endDay
44%9%16%24%6%
2700
July1st to 10thDay
35%8%14%31%12%1
2626
11th to 20thDay
39%8%14%30%8%
2545
21st to endDay
39%8%17%27%8%1
2591
August1st to 10thDay
39%9%18%25%7%1
2492
11th to 20thDay
38%10%19%27%7%
2335
21st to endDay
40%8%17%25%9%
2462
September1st to 10thDay
42%7%16%27%8%
2160
11th to 20thDay
47%8%20%20%5%
2160
21st to endDay
52%7%15%22%4
1900
October1st to 10thDay
56%8%13%19%4
1800
11th to 20thDay
62%6%12%16%4
1800
21st to endDay
64%5%11%17%3
1805
November1st to 10thDay
65%6%12%11%41
1528
11th to 20thDay
72%48%12%4
1520
21st to endDay
73%6%10%7%4
1520
December1st to 10thDay
72%7%8%11%3
1520
11th to 20thDay
67%5%10%11%6%1
1870
21st to endDay
75%35%13%4
2442
January1st to 10thNight
65%5%11%15%4
4737
11th to 20thNight
71%6%9%11%3
4502
21st to endNight
72%5%9%10%4
4884
February1st to 10thNight
58%5%12%15%9%
2404
11th to 20thNight
52%5%14%18%10%1
2274
21st to endNight
59%5%10%15%9%2
1854
March1st to 10thNight
57%5%11%15%11%2
2160
11th to 20thNight
50%412%19%12%2
1980
21st to endNight
49%6%13%19%10%3
2080
April1st to 10thNight
51%6%10%19%14%1
1800
11th to 20thNight
53%5%10%18%12%2
1760
21st to endNight
52%5%10%19%13%1
1526
May1st to 10thNight
50%7%11%20%11%
1440
11th to 20thNight
45%6%12%21%13%2
1417
21st to endNight
44%6%11%23%14%2
1552
June1st to 10thNight
43%7%14%24%11%1
1347
11th to 20thNight
37%8%11%24%19%1
1260
21st to endNight
40%10%15%24%9%1
1260
July1st to 10thNight
29%8%15%35%13%
1225
11th to 20thNight
30%9%17%30%13%
1290
21st to endNight
32%9%16%30%12%1
1487
August1st to 10thNight
32%8%19%28%11%2
1423
11th to 20thNight
36%9%15%31%8%
1562
21st to endNight
38%7%18%26%11%
1894
September1st to 10thNight
38%7%16%30%9%
1800
11th to 20thNight
40%8%19%27%5%
1800
21st to endNight
50%6%12%26%5%
2038
October1st to 10thNight
53%7%11%23%6%
2160
11th to 20thNight
56%5%13%21%3
2160
21st to endNight
61%7%13%14%4
2550
November1st to 10thNight
62%6%12%15%5%
2548
11th to 20thNight
71%5%9%10%4
2660
21st to endNight
71%6%10%10%3
2660
December1st to 10thNight
72%7%8%10%3
2660
11th to 20thNight
66%7%11%12%4
3321
21st to endNight
77%45%10%3
5225

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
15%14%41%21%9%
270
11th to 20thDay
17%10%41%25%7%1
270
21st to endDay
15%11%42%26%6%
297
February1st to 10thDay
15%18%45%15%7%
252
11th to 20thDay
19%19%40%15%5%3
240
21st to endDay
17%22%45%12%4
198
March1st to 10thDay
10%15%40%27%7%
240
11th to 20thDay
12%24%37%19%5%3
240
21st to endDay
18%18%33%19%9%3
362
April1st to 10thDay
22%16%33%18%9%1
420
11th to 20thDay
25%14%27%22%10%1
424
21st to endDay
25%15%28%22%8%2
600
May1st to 10thDay
25%18%31%20%5%2
603
11th to 20thDay
21%13%34%20%9%3
625
21st to endDay
23%12%30%26%7%2
679
June1st to 10thDay
20%13%30%24%10%3
630
11th to 20thDay
17%17%34%21%8%3
630
21st to endDay
20%10%29%24%12%4
630
July1st to 10thDay
11%10%34%25%14%5%
621
11th to 20thDay
17%12%29%24%13%5%
618
21st to endDay
12%9%32%25%16%6%
684
August1st to 10thDay
14%9%32%27%15%3
626
11th to 20thDay
18%8%25%27%17%5%
615
21st to endDay
20%9%29%24%15%2
581
September1st to 10thDay
17%13%31%25%13%2
450
11th to 20thDay
23%13%30%22%10%2
450
21st to endDay
31%15%26%17%10%
338
October1st to 10thDay
23%19%30%18%9%2
270
11th to 20thDay
24%19%34%18%4
270
21st to endDay
37%20%31%9%21
297
November1st to 10thDay
26%17%35%16%6%
270
11th to 20thDay
24%21%36%16%3
270
21st to endDay
27%20%36%13%31
270
December1st to 10thDay
16%19%44%16%4
270
11th to 20thDay
21%16%41%17%4
270
21st to endDay
22%15%37%21%32
297
January1st to 10thNight
16%13%38%25%8%1
950
11th to 20thNight
18%12%38%24%7%1
950
21st to endNight
17%11%38%26%7%
1045
February1st to 10thNight
14%13%36%26%10%1
923
11th to 20thNight
15%14%34%26%9%3
879
21st to endNight
13%15%35%26%10%1
670
March1st to 10thNight
16%14%35%26%9%
720
11th to 20thNight
18%15%35%22%9%1
540
21st to endNight
21%11%28%26%10%3
594
April1st to 10thNight
21%12%33%26%8%
540
11th to 20thNight
21%12%31%25%11%
533
21st to endNight
24%8%29%29%10%1
540
May1st to 10thNight
22%9%34%27%7%1
540
11th to 20thNight
21%12%29%24%13%2
531
21st to endNight
21%8%27%32%11%
584
June1st to 10thNight
21%6%29%30%14%
540
11th to 20thNight
16%6%32%35%11%
540
21st to endNight
16%6%24%36%16%1
540
July1st to 10thNight
10%6%29%38%17%1
525
11th to 20thNight
12%6%33%29%19%2
522
21st to endNight
9%5%26%37%20%2
591
August1st to 10thNight
10%430%38%18%1
537
11th to 20thNight
14%8%22%32%22%3
534
21st to endNight
19%7%24%32%17%1
594
September1st to 10thNight
15%6%28%33%17%1
540
11th to 20thNight
21%7%28%27%16%1
540
21st to endNight
29%10%26%25%8%1
670
October1st to 10thNight
27%11%30%23%9%1
720
11th to 20thNight
28%13%29%23%6%1
720
21st to endNight
28%13%30%24%6%
792
November1st to 10thNight
26%12%31%24%6%1
882
11th to 20thNight
26%14%32%20%7%1
950
21st to endNight
24%17%37%19%4
950
December1st to 10thNight
18%13%38%23%6%1
950
11th to 20thNight
21%14%36%22%7%1
950
21st to endNight
26%12%31%22%7%1
1045
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