Sioux Lookout
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sioux Lookout clear sky chart from 2005-11-05 to 2017-11-30.

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%
16619
10%
47661
6%
16572
33%
16572
15%
36351

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
20%
900
6%
2685
3%
895
23%
895
8%
2259
January16th to endNight
19%
960
7%
2748
3%
960
22%
960
8%
2356
February1st to 15thNight
29%
879
12%
2312
5%
875
33%
875
15%
1798
February16th to endNight
34%
762
11%
2024
5%
762
38%
762
16%
1557
March1st to 15thNight
30%
657
13%
2097
9%
657
35%
657
17%
1493
March16th to endNight
32%
576
16%
2049
12%
576
41%
576
16%
1417
April1st to 15thNight
34%
539
15%
1797
12%
539
41%
539
21%
1179
April16th to endNight
37%
540
17%
1562
9%
540
43%
540
24%
1053
May1st to 15thNight
27%
540
11%
1440
4%
540
31%
540
18%
1078
May16th to endNight
36%
563
7%
1468
4%
561
37%
561
22%
1077
June1st to 15thNight
39%
540
3%
1260
2%
540
40%
540
26%
914
June16th to endNight
45%
540
2%
1260
2%
540
46%
540
27%
899
July1st to 15thNight
48%
510
4%
1190
3%
510
49%
510
36%
802
July16th to endNight
50%
564
11%
1335
6%
531
51%
531
33%
893
August1st to 15thNight
50%
539
15%
1446
8%
536
52%
536
30%
946
August16th to endNight
45%
573
16%
1773
13%
573
50%
573
29%
1103
September1st to 15thNight
42%
540
12%
1800
11%
540
47%
540
23%
1160
September16th to endNight
32%
618
12%
1965
10%
618
36%
618
17%
1402
October1st to 15thNight
25%
720
13%
2160
7%
720
30%
720
16%
1581
October16th to endNight
20%
774
8%
2434
4%
774
25%
774
10%
1964
November1st to 15thNight
16%
950
6%
2661
2%
950
19%
950
9%
2242
November16th to endNight
14%
975
7%
2729
2%
975
18%
975
7%
2386
December1st to 15thNight
17%
900
4%
2586
2%
900
19%
900
6%
2250
December16th to endNight
17%
960
7%
2880
4%
960
20%
960
6%
2542

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
16%10%47%5%35%5%5%6%28%
48771
Night
15%11%5%8%6%35%5%45%27%
47814
Cloud CoverDay
16%10%47%6%35%5%5%6%29%
48781
Night
15%11%5%8%6%35%5%45%27%
47819
Cloud CoverDay
16%10%47%6%35%5%5%6%28%
48779
Night
15%11%5%8%6%35%5%45%27%
47819
TransparencyDay
55%6%12%18%6%
48442
Night
57%5%11%17%6%
47661
SeeingDay
22%11%30%21%10%2
6510
Night
21%9%30%26%10%1
16620

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
12%13%5%14%7%49%7%45%14%
1253
16th to endDay
11%14%7%10%9%7%8%7%6%5%11%
1476
February1st to 15thDay
8%11%5%8%7%5%8%11%5%5%22%
1551
16th to endDay
7%12%5%11%8%46%5%5%5%25%
1449
March1st to 15thDay
10%13%6%8%6%45%445%30%
1863
16th to endDay
15%9%49%5%35%446%31%
2175
April1st to 15thDay
11%9%47%5%2345%6%37%
2151
16th to endDay
16%9%35%4235%45%37%
2395
May1st to 15thDay
19%10%5%7%5%44446%28%
2511
16th to endDay
21%7%35%5%35%446%33%
2644
June1st to 15thDay
20%6%25%435%45%7%32%
2700
16th to endDay
18%5%36%6%45%6%6%7%28%
2700
July1st to 15thDay
16%5%26%435%5%5%7%37%
2700
16th to endDay
14%5%24425%5%6%8%39%
2741
August1st to 15thDay
12%5%26%4445%6%8%38%
2503
16th to endDay
15%6%25%4245%5%8%39%
2429
September1st to 15thDay
18%8%26%433445%37%
2160
16th to endDay
25%9%345%23435%31%
1982
October1st to 15thDay
20%16%47%6%3335%5%23%
1800
16th to endDay
24%20%5%7%5%2323418%
1789
November1st to 15thDay
20%19%6%9%6%3433318%
1527
16th to endDay
17%17%8%15%9%4444310%
1557
December1st to 15thDay
11%15%9%14%9%6%8%7%438%
1371
16th to endDay
18%16%8%12%7%46%5%46%9%
1344
January1st to 15thNight
10%15%6%12%9%6%8%6%5%5%13%
2685
16th to endNight
11%13%8%12%9%5%8%8%5%412%
2748
February1st to 15thNight
8%12%47%7%6%9%8%5%5%24%
2309
16th to endNight
7%13%5%9%7%37%7%5%6%26%
2024
March1st to 15thNight
11%11%48%6%34445%34%
2084
16th to endNight
14%12%5%6%5%24345%35%
2049
April1st to 15thNight
12%10%46%5%2345%5%40%
1797
16th to endNight
14%9%36%4335%45%39%
1562
May1st to 15thNight
21%10%35%4245%46%30%
1440
16th to endNight
20%8%345%2435%7%33%
1466
June1st to 15thNight
19%7%34324447%37%
1260
16th to endNight
14%425%436%5%6%8%38%
1260
July1st to 15thNight
11%4345%2445%9%43%
1260
16th to endNight
13%5%2342335%9%45%
1427
August1st to 15thNight
10%6%25%5%3445%7%44%
1455
16th to endNight
15%6%15%32335%7%45%
1773
September1st to 15thNight
16%5%25%4245%5%7%40%
1800
16th to endNight
23%8%345%2344435%
1965
October1st to 15thNight
20%11%36%5%2435%5%31%
2160
16th to endNight
22%17%48%5%43335%21%
2434
November1st to 15thNight
20%18%6%9%6%2433418%
2661
16th to endNight
18%15%7%13%10%45%42314%
2729
December1st to 15thNight
12%11%8%14%12%5%7%6%3411%
2586
16th to endNight
15%18%7%13%10%46%43311%
2880

Percentage Cloud Cover SW (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
12%13%5%13%8%49%7%4415%
1253
16th to endDay
11%14%6%10%9%7%8%7%6%5%11%
1476
February1st to 15thDay
8%11%5%8%6%5%9%10%5%5%22%
1551
16th to endDay
7%12%412%8%46%5%5%5%25%
1449
March1st to 15thDay
10%13%6%8%6%345%45%30%
1873
16th to endDay
15%10%48%5%35%446%30%
2175
April1st to 15thDay
11%10%46%5%2345%7%37%
2151
16th to endDay
16%9%35%434445%38%
2395
May1st to 15thDay
19%10%47%5%35%446%28%
2511
16th to endDay
21%7%35%43445%6%33%
2644
June1st to 15thDay
20%6%25%435%46%8%32%
2700
16th to endDay
18%5%36%6%35%6%6%8%29%
2700
July1st to 15thDay
16%5%35%445%46%7%37%
2700
16th to endDay
14%5%245%25%46%8%39%
2741
August1st to 15thDay
12%5%35%435%5%6%8%38%
2503
16th to endDay
15%6%35%425%36%7%39%
2429
September1st to 15thDay
18%8%35%434445%37%
2160
16th to endDay
25%10%25%423335%32%
1982
October1st to 15thDay
20%15%48%5%34445%23%
1800
16th to endDay
24%19%6%7%433335%18%
1789
November1st to 15thDay
20%19%7%9%6%3333417%
1527
16th to endDay
17%18%7%15%9%444349%
1557
December1st to 15thDay
11%15%10%13%9%6%8%7%5%38%
1371
16th to endDay
17%16%9%12%7%46%5%46%9%
1344
January1st to 15thNight
10%15%7%12%8%6%7%6%6%5%13%
2685
16th to endNight
11%14%7%13%9%5%8%8%5%413%
2748
February1st to 15thNight
8%12%46%7%5%9%8%5%5%24%
2302
16th to endNight
8%12%5%9%8%37%6%5%6%26%
2024
March1st to 15thNight
12%11%5%8%6%34435%34%
2097
16th to endNight
15%12%5%5%5%2434435%
2049
April1st to 15thNight
12%11%37%5%2345%5%40%
1797
16th to endNight
14%9%26%5%2345%5%39%
1562
May1st to 15thNight
21%10%35%434446%31%
1439
16th to endNight
20%7%35%5%24447%33%
1466
June1st to 15thNight
20%6%35%424437%37%
1260
16th to endNight
15%4245%36%5%6%7%39%
1260
July1st to 15thNight
11%43443445%9%43%
1260
16th to endNight
13%42442335%8%46%
1427
August1st to 15thNight
10%6%25%5%3445%7%45%
1455
16th to endNight
14%5%2442335%7%45%
1773
September1st to 15thNight
16%6%25%43345%7%40%
1800
16th to endNight
23%7%35%433445%34%
1965
October1st to 15thNight
20%12%36%5%24345%31%
2160
16th to endNight
22%17%47%5%34435%22%
2434
November1st to 15thNight
20%19%6%9%6%3343418%
2661
16th to endNight
18%15%7%12%10%5%433314%
2729
December1st to 15thNight
11%12%8%14%12%6%7%5%4412%
2586
16th to endNight
15%18%8%13%10%46%43311%
2880

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
12%13%5%14%8%49%6%5%414%
1253
16th to endDay
11%13%7%11%9%8%7%6%7%411%
1476
February1st to 15thDay
8%11%5%7%7%6%8%11%46%21%
1551
16th to endDay
7%12%5%11%8%45%5%6%5%25%
1449
March1st to 15thDay
10%12%6%8%6%35%445%30%
1873
16th to endDay
15%9%48%6%35%446%30%
2173
April1st to 15thDay
10%10%47%5%2345%7%37%
2151
16th to endDay
16%9%35%4235%45%37%
2395
May1st to 15thDay
18%10%47%5%34446%28%
2511
16th to endDay
22%6%25%5%34446%32%
2644
June1st to 15thDay
20%6%35%5%35%45%7%32%
2700
16th to endDay
18%5%36%6%35%6%6%7%28%
2700
July1st to 15thDay
15%5%36%4345%5%7%37%
2700
16th to endDay
14%5%25%425%5%5%7%39%
2741
August1st to 15thDay
12%5%26%435%5%6%8%37%
2503
16th to endDay
15%5%25%43445%8%39%
2429
September1st to 15thDay
19%7%35%5%345%45%36%
2160
16th to endDay
25%9%34433335%31%
1982
October1st to 15thDay
20%16%5%7%5%3435%5%23%
1800
16th to endDay
24%21%5%7%5%2333418%
1789
November1st to 15thDay
20%19%7%10%7%2333317%
1527
16th to endDay
16%18%9%15%9%444339%
1557
December1st to 15thDay
11%15%10%13%9%6%8%7%438%
1371
16th to endDay
18%16%8%12%8%46%5%46%8%
1344
January1st to 15thNight
10%15%7%11%9%6%8%6%6%412%
2685
16th to endNight
10%14%7%12%9%5%8%9%4412%
2748
February1st to 15thNight
8%12%46%7%5%10%8%5%5%23%
2302
16th to endNight
7%13%5%9%7%37%6%46%26%
2024
March1st to 15thNight
12%11%48%6%24445%34%
2097
16th to endNight
15%11%5%5%5%2434435%
2049
April1st to 15thNight
12%10%46%5%23446%39%
1797
16th to endNight
14%9%26%4345%45%39%
1562
May1st to 15thNight
20%10%45%425%5%46%31%
1439
16th to endNight
20%7%35%5%3445%7%32%
1466
June1st to 15thNight
20%7%25%334446%38%
1260
16th to endNight
15%416%435%6%5%8%38%
1260
July1st to 15thNight
11%4345%3445%9%43%
1260
16th to endNight
14%5%2343335%9%45%
1427
August1st to 15thNight
10%6%26%5%3445%7%44%
1455
16th to endNight
15%6%1442335%6%45%
1773
September1st to 15thNight
16%6%244245%5%7%40%
1800
16th to endNight
23%8%345%23345%35%
1965
October1st to 15thNight
20%11%36%42335%5%31%
2160
16th to endNight
22%17%47%5%34335%21%
2434
November1st to 15thNight
20%18%6%9%6%3433418%
2661
16th to endNight
18%15%7%13%10%45%32314%
2729
December1st to 15thNight
11%12%7%14%12%6%7%6%4412%
2586
16th to endNight
15%18%7%13%10%46%5%3311%
2880

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
69%5%9%12%2
1254
16th to endDay
71%48%11%4
1476
February1st to 15thDay
59%6%9%17%6%
1552
16th to endDay
58%411%20%4
1449
March1st to 15thDay
54%6%12%17%8%
1873
16th to endDay
53%5%11%17%8%2
2175
April1st to 15thDay
46%5%10%21%13%3
2151
16th to endDay
48%49%23%11%1
2395
May1st to 15thDay
56%6%9%20%7%
2511
16th to endDay
51%6%12%18%10%
2648
June1st to 15thDay
50%7%10%19%11%
2700
16th to endDay
51%9%14%18%6%
2700
July1st to 15thDay
43%8%12%27%7%
2541
16th to endDay
42%8%15%25%8%
2570
August1st to 15thDay
40%9%18%25%5%
2488
16th to endDay
42%7%16%25%7%
2429
September1st to 15thDay
48%6%14%24%5%
2160
16th to endDay
55%6%15%19%3
1982
October1st to 15thDay
61%5%13%15%4
1800
16th to endDay
70%412%11%1
1789
November1st to 15thDay
72%411%7%3
1527
16th to endDay
78%5%7%6%2
1557
December1st to 15thDay
78%5%7%6%1
1371
16th to endDay
75%47%8%4
1344
January1st to 15thNight
70%5%8%13%2
2685
16th to endNight
71%6%6%11%3
2748
February1st to 15thNight
58%5%11%16%7%
2312
16th to endNight
56%6%11%20%4
2024
March1st to 15thNight
52%5%13%16%10%1
2097
16th to endNight
51%411%19%8%3
2049
April1st to 15thNight
45%49%22%15%1
1797
16th to endNight
45%49%23%15%1
1562
May1st to 15thNight
53%5%9%19%10%
1440
16th to endNight
50%6%11%18%11%2
1468
June1st to 15thNight
47%5%10%20%16%
1260
16th to endNight
41%9%14%24%9%
1260
July1st to 15thNight
34%8%16%28%11%
1190
16th to endNight
37%7%12%31%9%2
1335
August1st to 15thNight
37%7%14%28%10%1
1446
16th to endNight
37%5%18%27%9%1
1773
September1st to 15thNight
42%6%16%26%8%
1800
16th to endNight
51%5%15%22%4
1965
October1st to 15thNight
54%5%14%20%5%
2160
16th to endNight
65%5%12%13%2
2434
November1st to 15thNight
70%410%11%2
2661
16th to endNight
76%38%8%2
2729
December1st to 15thNight
73%6%9%7%2
2586
16th to endNight
77%46%8%2
2880

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
11%13%42%30%3
90
16th to endDay
29%434%21%8%2
96
February1st to 15thDay
23%13%38%17%6%
90
16th to endDay
22%16%40%13%42
81
March1st to 15thDay
13%12%40%23%8%2
90
16th to endDay
17%13%29%25%10%3
159
April1st to 15thDay
14%11%28%30%12%1
270
16th to endDay
23%10%32%22%10%
429
May1st to 15thDay
26%16%30%17%6%2
468
16th to endDay
28%10%29%18%10%2
517
June1st to 15thDay
25%11%30%20%7%3
495
16th to endDay
21%12%27%21%12%5%
495
July1st to 15thDay
16%10%30%25%12%3
475
16th to endDay
16%11%27%24%13%6%
515
August1st to 15thDay
15%5%29%27%17%4
493
16th to endDay
22%8%29%23%14%1
469
September1st to 15thDay
20%9%30%25%11%2
315
16th to endDay
35%11%27%20%3
229
October1st to 15thDay
29%20%23%18%5%2
135
16th to endDay
42%8%36%11%2
144
November1st to 15thDay
36%14%34%8%5%
135
16th to endDay
33%21%29%10%5%
134
December1st to 15thDay
22%11%43%18%22
90
16th to endDay
27%9%36%20%33
96
January1st to 15thNight
18%12%35%24%8%
900
16th to endNight
18%11%35%25%7%
960
February1st to 15thNight
14%10%35%28%9%1
880
16th to endNight
13%10%30%29%12%3
762
March1st to 15thNight
17%13%31%23%12%1
657
16th to endNight
21%11%26%25%10%4
576
April1st to 15thNight
16%11%29%31%10%
539
16th to endNight
18%9%29%30%10%1
540
May1st to 15thNight
26%11%30%25%5%1
540
16th to endNight
23%7%28%28%11%
563
June1st to 15thNight
24%7%25%27%13%1
540
16th to endNight
16%7%23%35%15%1
540
July1st to 15thNight
12%6%29%33%16%1
510
16th to endNight
16%424%31%20%3
564
August1st to 15thNight
13%5%24%28%24%2
539
16th to endNight
18%5%26%30%17%1
573
September1st to 15thNight
21%5%24%31%14%1
540
16th to endNight
28%8%26%25%9%1
618
October1st to 15thNight
28%11%29%22%7%
720
16th to endNight
34%8%28%19%7%1
774
November1st to 15thNight
29%13%29%20%41
950
16th to endNight
27%12%33%20%41
975
December1st to 15thNight
17%11%36%25%7%1
900
16th to endNight
22%9%32%23%8%2
960
Page generated at 2017-12-01 11:13:45. Version ac04

Copyright 2017 A. Danko


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