Okotoks
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Okotoks 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
41%
23509
16%
80464
10%
23443
47%
23443
23%
50325

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
33%
939
15%
4668
8%
926
39%
926
12%
3070
January11th to 20thNight
36%
911
20%
4580
12%
902
43%
902
14%
2894
January21st to endNight
35%
824
14%
4800
14%
814
48%
814
14%
2684
February1st to 10thNight
35%
738
15%
2582
11%
738
43%
738
18%
1713
February11th to 20thNight
36%
704
15%
2273
11%
700
43%
700
18%
1556
February21st to endNight
41%
592
18%
1808
12%
592
51%
592
21%
1260
March1st to 10thNight
37%
720
17%
2160
12%
720
44%
720
21%
1490
March11th to 20thNight
37%
720
20%
2003
11%
720
44%
720
25%
1344
March21st to endNight
36%
792
12%
2148
5%
792
40%
792
21%
1518
April1st to 10thNight
34%
676
15%
1756
5%
676
39%
676
21%
1265
April11th to 20thNight
31%
533
14%
1601
9%
533
35%
533
19%
1126
April21st to endNight
34%
540
13%
1620
8%
540
40%
540
22%
1095
May1st to 10thNight
40%
468
10%
1522
8%
468
45%
468
19%
1023
May11th to 20thNight
47%
354
15%
1239
15%
354
53%
354
26%
749
May21st to endNight
43%
388
6%
1358
3%
388
45%
388
19%
911
June1st to 10thNight
42%
360
4%
1260
1%
360
43%
360
22%
800
June11th to 20thNight
39%
360
2%
1260
0%
360
39%
360
20%
838
June21st to endNight
59%
360
2%
1260
0%
360
59%
360
33%
683
July1st to 10thNight
62%
350
4%
1225
0%
350
62%
350
31%
682
July11th to 20thNight
58%
348
7%
1218
5%
348
60%
348
31%
672
July21st to endNight
63%
394
16%
1378
18%
372
69%
372
39%
663
August1st to 10thNight
63%
358
15%
1424
21%
356
68%
356
28%
762
August11th to 20thNight
64%
517
19%
1585
18%
517
67%
517
40%
855
August21st to endNight
57%
594
23%
1782
18%
594
60%
594
41%
962
September1st to 10thNight
53%
636
20%
1733
12%
636
57%
636
39%
1037
September11th to 20thNight
53%
720
21%
1980
14%
720
57%
720
37%
1195
September21st to endNight
45%
720
23%
1980
13%
720
53%
720
36%
1199
October1st to 10thNight
46%
720
21%
2053
14%
720
53%
720
30%
1320
October11th to 20thNight
42%
720
20%
2288
12%
720
52%
720
30%
1367
October21st to endNight
38%
792
20%
2574
12%
792
49%
792
25%
1608
November1st to 10thNight
30%
830
18%
2495
8%
830
40%
830
21%
1679
November11th to 20thNight
32%
950
21%
2715
10%
950
42%
950
27%
1736
November21st to endNight
35%
950
17%
2850
7%
950
44%
950
27%
1801
December1st to 10thNight
38%
950
17%
2850
11%
950
44%
950
23%
1909
December11th to 20thNight
34%
950
15%
3477
9%
949
40%
949
19%
2210
December21st to endNight
34%
1031
12%
4959
8%
1026
42%
1026
16%
2649

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
9%8%37%6%35%5%6%8%38%
77703
Night
6%9%48%6%45%5%6%8%39%
81115
TransparencyDay
42%6%16%24%11%2
77410
Night
41%6%15%24%12%2
80988
SeeingDay
13%10%30%29%15%4
14239
Night
11%7%31%35%14%2
23558

By Month

Percentage Cloud Cover NW (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
210%7%10%7%45%6%7%9%34%
2219
11th to 20thDay
48%39%7%46%7%7%7%37%
2269
21st to endDay
38%37%7%46%5%6%9%42%
2794
February1st to 10thDay
39%5%11%8%37%6%7%8%32%
1472
11th to 20thDay
410%7%9%8%5%7%7%7%8%29%
1575
21st to endDay
311%6%12%8%5%7%5%5%8%31%
1446
March1st to 10thDay
49%5%10%9%46%6%5%9%34%
1800
11th to 20thDay
5%10%48%5%36%6%6%9%39%
1955
21st to endDay
7%14%5%10%6%45%6%7%7%28%
2204
April1st to 10thDay
9%13%5%9%7%46%5%6%7%29%
2204
11th to 20thDay
11%12%5%8%6%35%5%6%8%31%
2310
21st to endDay
13%11%37%6%35%6%7%8%32%
2340
May1st to 10thDay
13%11%47%7%46%6%7%8%28%
2435
11th to 20thDay
13%7%37%6%46%5%6%8%35%
2654
21st to endDay
21%7%36%6%5%5%5%6%8%29%
2917
June1st to 10thDay
16%8%36%6%46%6%8%8%29%
2700
11th to 20thDay
21%7%47%7%46%6%6%9%26%
2700
21st to endDay
9%4246%35%7%7%10%43%
2700
July1st to 10thDay
8%425%6%36%6%7%9%43%
2700
11th to 20thDay
9%425%4345%7%8%48%
2700
21st to endDay
4323435%5%7%9%55%
2857
August1st to 10thDay
10%5%244346%7%9%47%
2507
11th to 20thDay
9%4243345%7%9%50%
2316
21st to endDay
10%4244345%6%8%50%
2574
September1st to 10thDay
11%5%15%5%34447%51%
2224
11th to 20thDay
13%8%2443445%7%45%
1980
21st to endDay
8%8%36%5%3446%8%45%
1980
October1st to 10thDay
11%10%36%5%345%5%7%40%
1907
11th to 20thDay
8%9%47%6%3446%9%39%
1670
21st to endDay
6%11%36%6%36%6%7%8%36%
1782
November1st to 10thDay
8%14%5%8%6%346%48%33%
1565
11th to 20thDay
5%11%47%6%345%6%9%40%
1463
21st to endDay
410%6%8%5%35%6%7%10%37%
1330
December1st to 10thDay
410%49%8%5%6%46%8%36%
1330
11th to 20thDay
211%5%11%8%46%7%6%7%33%
1682
21st to endDay
48%37%6%35%5%5%9%46%
2442
January1st to 10thNight
310%5%11%9%5%7%6%7%8%29%
4726
11th to 20thNight
37%5%12%7%46%8%6%9%34%
4658
21st to endNight
410%49%7%45%5%6%8%39%
4862
February1st to 10thNight
49%6%10%7%5%6%6%6%9%33%
2582
11th to 20thNight
413%6%9%7%46%6%6%9%31%
2272
21st to endNight
39%6%11%10%5%6%5%5%7%34%
1808
March1st to 10thNight
310%5%9%9%46%6%5%9%32%
2160
11th to 20thNight
410%47%6%46%6%6%9%37%
2003
21st to endNight
5%12%6%9%7%45%5%7%9%31%
2148
April1st to 10thNight
8%14%5%7%7%46%5%6%7%32%
1756
11th to 20thNight
11%12%5%9%7%435%6%7%32%
1601
21st to endNight
11%10%47%6%35%5%6%9%35%
1620
May1st to 10thNight
11%10%5%7%6%35%5%6%8%33%
1522
11th to 20thNight
11%6%36%5%35%6%5%9%42%
1239
21st to endNight
19%7%36%5%36%5%6%8%32%
1358
June1st to 10thNight
14%7%36%6%445%7%9%36%
1260
11th to 20thNight
18%7%46%5%35%5%6%9%31%
1260
21st to endNight
7%5%244445%9%9%46%
1260
July1st to 10thNight
7%5%25%5%4436%9%49%
1260
11th to 20thNight
7%425%5%36%5%6%10%47%
1260
21st to endNight
6%32432446%8%58%
1459
August1st to 10thNight
9%415%5%445%6%8%48%
1432
11th to 20thNight
8%4133346%6%10%52%
1585
21st to endNight
9%42432445%9%54%
1782
September1st to 10thNight
10%6%243245%5%8%50%
1733
11th to 20thNight
13%7%2432235%7%51%
1980
21st to endNight
9%7%344245%6%8%48%
1980
October1st to 10thNight
10%9%36%5%3445%6%44%
2053
11th to 20thNight
8%8%35%5%345%7%8%44%
2288
21st to endNight
7%10%46%5%35%6%6%8%39%
2574
November1st to 10thNight
8%12%5%7%6%46%46%7%36%
2495
11th to 20thNight
49%46%7%45%5%6%8%42%
2715
21st to endNight
49%5%8%6%35%5%6%9%40%
2850
December1st to 10thNight
410%5%8%7%47%6%7%8%35%
2850
11th to 20thNight
28%5%11%9%46%7%7%8%34%
3510
21st to endNight
39%37%6%45%5%6%8%43%
5214

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
42%7%15%23%10%3
2219
11th to 20thDay
44%5%11%18%18%4
2290
21st to endDay
37%5%16%31%9%1
2794
February1st to 10thDay
47%7%14%20%9%3
1472
11th to 20thDay
49%7%14%21%9%1
1584
21st to endDay
50%413%18%14%1
1446
March1st to 10thDay
44%8%15%21%10%1
1800
11th to 20thDay
40%6%14%25%13%2
1956
21st to endDay
52%6%17%19%6%1
2204
April1st to 10thDay
51%7%14%20%8%1
2204
11th to 20thDay
50%5%12%21%10%2
2310
21st to endDay
48%5%15%22%9%1
2340
May1st to 10thDay
51%5%15%22%7%
2435
11th to 20thDay
44%6%15%23%10%1
2658
21st to endDay
52%6%15%20%7%1
2918
June1st to 10thDay
49%6%16%19%8%1
2700
11th to 20thDay
53%5%17%16%7%2
2700
21st to endDay
34%7%20%26%11%3
2700
July1st to 10thDay
35%5%20%25%12%2
2626
11th to 20thDay
32%6%18%28%15%2
2619
21st to endDay
24%5%18%32%17%3
2698
August1st to 10thDay
32%6%20%29%12%2
2490
11th to 20thDay
29%6%23%29%11%3
2316
21st to endDay
30%6%17%29%16%2
2574
September1st to 10thDay
34%415%26%17%4
2224
11th to 20thDay
37%5%15%27%14%2
1980
21st to endDay
37%415%29%13%3
1980
October1st to 10thDay
42%6%16%24%11%2
1907
11th to 20thDay
42%416%25%11%3
1670
21st to endDay
42%7%13%24%11%3
1782
November1st to 10thDay
48%6%12%20%11%2
1565
11th to 20thDay
41%5%18%24%11%2
1463
21st to endDay
39%7%18%22%10%3
1330
December1st to 10thDay
45%5%14%19%13%4
1330
11th to 20thDay
48%6%16%20%8%1
1684
21st to endDay
35%5%11%25%19%6%
2442
January1st to 10thNight
49%7%13%21%7%2
4726
11th to 20thNight
46%5%12%17%14%5%
4699
21st to endNight
42%5%16%24%13%1
4862
February1st to 10thNight
46%6%13%21%12%3
2582
11th to 20thNight
49%6%14%20%11%1
2273
21st to endNight
49%5%9%22%12%3
1808
March1st to 10thNight
46%7%13%24%8%1
2160
11th to 20thNight
42%7%14%23%13%1
2003
21st to endNight
48%6%17%19%9%1
2148
April1st to 10thNight
48%7%11%22%11%1
1756
11th to 20thNight
50%5%13%21%9%1
1601
21st to endNight
46%6%15%23%9%2
1620
May1st to 10thNight
47%5%14%22%12%
1522
11th to 20thNight
38%5%14%31%10%1
1239
21st to endNight
48%6%16%22%7%1
1358
June1st to 10thNight
44%5%16%23%11%1
1260
11th to 20thNight
47%5%17%19%10%2
1260
21st to endNight
31%5%23%27%12%2
1260
July1st to 10thNight
32%6%19%27%14%1
1225
11th to 20thNight
31%6%20%27%12%3
1218
21st to endNight
23%6%16%32%20%4
1378
August1st to 10thNight
33%5%17%29%12%3
1424
11th to 20thNight
26%6%21%31%14%2
1585
21st to endNight
27%5%14%32%19%4
1782
September1st to 10thNight
31%5%16%28%16%4
1733
11th to 20thNight
33%414%30%14%5%
1980
21st to endNight
34%417%26%14%5%
1980
October1st to 10thNight
39%5%14%25%16%1
2053
11th to 20thNight
36%5%16%26%13%3
2288
21st to endNight
40%6%15%26%12%1
2574
November1st to 10thNight
46%6%14%21%13%2
2495
11th to 20thNight
38%6%16%22%16%1
2715
21st to endNight
39%5%17%22%12%4
2850
December1st to 10thNight
44%6%15%20%11%4
2850
11th to 20thNight
43%6%21%21%8%1
3507
21st to endNight
37%5%12%26%15%5%
5214

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
39%29%34%14%11%
180
11th to 20thDay
9%7%36%31%13%4
180
21st to endDay
8%10%22%45%12%4
198
February1st to 10thDay
9%13%39%29%9%2
168
11th to 20thDay
7%9%39%31%13%1
240
21st to endDay
5%12%33%33%16%1
312
March1st to 10thDay
8%17%41%21%10%3
420
11th to 20thDay
9%15%34%27%13%2
420
21st to endDay
13%18%33%21%11%3
462
April1st to 10thDay
14%18%35%25%7%1
420
11th to 20thDay
18%14%28%26%11%3
412
21st to endDay
17%19%31%21%10%2
420
May1st to 10thDay
19%9%29%25%14%4
447
11th to 20thDay
19%8%24%28%18%4
625
21st to endDay
20%6%24%27%20%4
679
June1st to 10thDay
17%9%28%30%13%3
630
11th to 20thDay
22%10%28%26%12%2
630
21st to endDay
12%7%26%31%18%5%
630
July1st to 10thDay
10%6%25%34%22%4
621
11th to 20thDay
11%7%27%33%19%3
618
21st to endDay
6%7%30%32%21%5%
603
August1st to 10thDay
9%7%30%33%17%4
447
11th to 20thDay
9%6%28%34%16%7%
437
21st to endDay
11%8%28%29%16%8%
495
September1st to 10thDay
14%9%32%28%14%4
450
11th to 20thDay
18%8%26%28%15%4
450
21st to endDay
15%17%24%29%11%3
450
October1st to 10thDay
14%11%25%28%18%4
377
11th to 20thDay
15%11%30%24%15%5%
270
21st to endDay
15%12%37%23%11%2
297
November1st to 10thDay
20%11%29%29%8%3
270
11th to 20thDay
12%15%32%30%9%2
243
21st to endDay
7%13%31%29%11%9%
180
December1st to 10thDay
7%8%34%30%18%3
180
11th to 20thDay
411%43%28%10%4
180
21st to endDay
9%5%29%31%23%4
198
January1st to 10thNight
9%10%36%34%10%1
950
11th to 20thNight
8%8%36%36%12%1
922
21st to endNight
9%10%33%37%10%1
836
February1st to 10thNight
8%11%32%32%13%3
738
11th to 20thNight
11%8%33%37%10%1
704
21st to endNight
6%5%30%37%19%3
592
March1st to 10thNight
9%6%36%34%13%3
720
11th to 20thNight
8%10%35%33%12%2
720
21st to endNight
11%8%31%36%11%3
792
April1st to 10thNight
12%11%31%32%12%1
676
11th to 20thNight
17%8%35%31%9%
533
21st to endNight
17%9%31%31%12%
540
May1st to 10thNight
16%10%25%31%18%
468
11th to 20thNight
14%8%23%33%21%1
354
21st to endNight
22%6%23%33%16%1
389
June1st to 10thNight
17%7%25%35%14%2
360
11th to 20thNight
21%6%28%31%13%1
360
21st to endNight
10%418%41%24%2
360
July1st to 10thNight
10%317%43%25%1
350
11th to 20thNight
10%320%44%21%2
348
21st to endNight
7%320%45%23%2
394
August1st to 10thNight
12%314%40%30%2
358
11th to 20thNight
10%318%44%22%2
517
21st to endNight
9%423%40%22%1
594
September1st to 10thNight
13%327%35%19%3
636
11th to 20thNight
19%321%35%20%3
720
21st to endNight
12%6%33%35%12%3
720
October1st to 10thNight
16%426%36%15%3
720
11th to 20thNight
13%6%31%32%14%4
720
21st to endNight
12%7%33%37%10%1
792
November1st to 10thNight
14%10%38%29%9%1
830
11th to 20thNight
10%13%39%31%7%1
950
21st to endNight
9%7%40%32%10%2
950
December1st to 10thNight
8%8%35%34%12%3
950
11th to 20thNight
5%8%40%36%9%1
950
21st to endNight
9%7%35%35%12%2
1045
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