Weyburn
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Weyburn clear sky chart from 2005-11-06 to 2024-02-15.

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
39%
24883
14%
80068
9%
24798
44%
24798
21%
53194

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
31%
936
13%
4374
6%
926
37%
926
12%
2965
January11th to 20thNight
28%
946
9%
4411
5%
930
32%
930
9%
3307
January21st to endNight
27%
1037
8%
4726
5%
1023
32%
1023
9%
3132
February1st to 10thNight
29%
936
11%
2646
5%
936
35%
936
15%
2022
February11th to 20thNight
30%
718
12%
2318
8%
718
36%
718
15%
1713
February21st to endNight
42%
592
18%
1776
12%
592
48%
592
22%
1223
March1st to 10thNight
32%
720
10%
2160
6%
720
35%
720
18%
1582
March11th to 20thNight
37%
720
17%
2111
10%
720
44%
720
23%
1450
March21st to endNight
39%
597
13%
1983
10%
597
43%
597
17%
1404
April1st to 10thNight
39%
540
19%
1800
15%
540
48%
540
26%
1098
April11th to 20thNight
30%
533
14%
1738
10%
533
38%
533
18%
1201
April21st to endNight
36%
540
15%
1534
10%
540
40%
540
24%
1047
May1st to 10thNight
48%
540
17%
1440
10%
540
50%
540
32%
916
May11th to 20thNight
48%
531
15%
1418
7%
531
50%
531
31%
912
May21st to endNight
43%
584
9%
1493
4%
582
45%
582
26%
1048
June1st to 10thNight
47%
540
8%
1260
3%
540
51%
540
37%
827
June11th to 20thNight
42%
452
6%
1172
4%
452
44%
452
31%
772
June21st to endNight
54%
360
8%
1080
8%
360
58%
360
32%
649
July1st to 10thNight
61%
424
9%
1206
7%
424
65%
424
44%
665
July11th to 20thNight
55%
522
12%
1392
7%
522
59%
522
42%
811
July21st to endNight
61%
591
19%
1488
11%
558
64%
558
51%
799
August1st to 10thNight
62%
537
19%
1424
11%
534
66%
534
43%
827
August11th to 20thNight
61%
534
24%
1424
16%
534
66%
534
44%
806
August21st to endNight
58%
594
25%
1953
21%
594
66%
594
42%
977
September1st to 10thNight
53%
540
22%
1800
21%
540
62%
540
35%
974
September11th to 20thNight
49%
540
22%
1841
19%
540
57%
540
31%
1056
September21st to endNight
45%
540
22%
1980
18%
540
54%
540
26%
1150
October1st to 10thNight
42%
697
19%
2137
12%
697
47%
697
26%
1363
October11th to 20thNight
43%
796
20%
2236
11%
796
49%
796
30%
1414
October21st to endNight
33%
990
17%
2574
7%
990
40%
990
24%
1811
November1st to 10thNight
30%
925
15%
2452
5%
925
36%
925
20%
1798
November11th to 20thNight
31%
950
14%
2660
7%
950
36%
950
18%
1967
November21st to endNight
28%
950
11%
2816
5%
950
34%
950
18%
2019
December1st to 10thNight
31%
950
10%
2850
5%
950
36%
950
16%
2118
December11th to 20thNight
24%
949
11%
3437
4%
948
31%
948
11%
2615
December21st to endNight
30%
1032
9%
4958
6%
1026
37%
1026
12%
2756

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
10%8%47%6%45%5%6%8%37%
78329
Night
8%8%48%7%45%5%6%8%37%
80771
TransparencyDay
44%7%15%23%9%1
78030
Night
44%7%15%22%10%1
80593
SeeingDay
12%9%30%30%16%3
15107
Night
12%7%32%35%12%1
24927

By Month

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 10thDay
7%13%5%12%10%6%8%7%6%8%20%
2538
11th to 20thDay
6%7%411%12%7%11%12%8%6%15%
2540
21st to endDay
5%11%5%10%9%47%5%5%6%31%
2794
February1st to 10thDay
10%12%6%11%9%48%7%6%5%22%
1550
11th to 20thDay
8%12%6%11%9%7%8%7%6%6%21%
1623
21st to endDay
6%10%6%11%10%6%7%7%7%7%24%
1480
March1st to 10thDay
9%12%7%13%9%5%6%5%6%8%22%
1800
11th to 20thDay
8%12%5%6%7%45%5%8%8%33%
1845
21st to endDay
9%10%6%11%7%5%5%5%7%10%26%
2372
April1st to 10thDay
8%7%36%7%45%5%6%8%40%
2160
11th to 20thDay
14%13%48%6%35%5%6%7%28%
2170
21st to endDay
13%9%36%6%445%5%7%37%
2424
May1st to 10thDay
12%8%36%6%3445%8%41%
2520
11th to 20thDay
11%8%26%5%35%5%6%9%40%
2478
21st to endDay
20%7%36%6%35%6%5%8%32%
2782
June1st to 10thDay
13%425%5%35%5%7%9%40%
2700
11th to 20thDay
15%6%36%6%46%6%6%9%35%
2780
21st to endDay
10%425%5%35%5%7%10%44%
2880
July1st to 10thDay
7%3236%35%5%6%9%52%
2707
11th to 20thDay
6%424435%6%6%9%51%
2520
21st to endDay
5%313335%6%7%8%56%
2742
August1st to 10thDay
8%415%5%345%6%8%51%
2507
11th to 20thDay
9%5%23435%5%6%9%49%
2477
21st to endDay
10%4244245%48%54%
2400
September1st to 10thDay
12%5%244345%5%8%49%
2160
11th to 20thDay
13%7%35%5%3345%7%46%
2118
21st to endDay
13%6%25%434448%48%
1980
October1st to 10thDay
15%10%35%43435%7%41%
1819
11th to 20thDay
11%7%47%5%2446%8%41%
1706
21st to endDay
11%12%5%9%5%345%5%7%34%
1782
November1st to 10thDay
12%13%5%9%7%45%5%5%5%30%
1625
11th to 20thDay
7%12%5%10%10%47%5%5%7%30%
1520
21st to endDay
8%14%6%9%7%5%6%5%5%7%29%
1361
December1st to 10thDay
8%12%8%11%11%46%5%6%8%22%
1330
11th to 20thDay
7%15%6%11%9%5%6%5%5%9%19%
1683
21st to endDay
6%7%38%5%45%6%6%7%42%
2456
January1st to 10thNight
412%5%10%11%46%6%6%7%29%
4417
11th to 20thNight
47%412%12%8%10%8%7%6%21%
4430
21st to endNight
6%11%5%9%9%46%5%7%9%30%
4873
February1st to 10thNight
8%12%6%9%9%5%7%7%6%8%23%
2646
11th to 20thNight
6%12%5%11%9%5%8%6%6%7%26%
2317
21st to endNight
5%8%5%11%8%5%6%6%6%8%34%
1776
March1st to 10thNight
7%10%5%12%9%45%5%6%8%29%
2160
11th to 20thNight
7%10%5%9%7%36%6%6%8%35%
2111
21st to endNight
9%11%5%9%7%37%5%5%9%30%
1983
April1st to 10thNight
6%8%46%5%345%6%7%45%
1800
11th to 20thNight
13%11%48%6%345%6%6%32%
1738
21st to endNight
13%9%37%5%346%6%7%37%
1534
May1st to 10thNight
12%7%35%43446%8%45%
1440
11th to 20thNight
13%5%25%4345%6%8%45%
1417
21st to endNight
15%5%35%5%35%5%6%10%36%
1493
June1st to 10thNight
13%42443446%8%47%
1260
11th to 20thNight
13%5%25%5%235%5%10%44%
1172
21st to endNight
9%326%4246%7%10%46%
1080
July1st to 10thNight
6%3144245%7%10%56%
1244
11th to 20thNight
6%3144345%5%7%57%
1440
21st to endNight
421442435%7%64%
1576
August1st to 10thNight
5%2245%445%5%9%55%
1432
11th to 20thNight
6%324325%36%8%57%
1424
21st to endNight
7%22442345%8%58%
1953
September1st to 10thNight
10%5%2442445%7%54%
1800
11th to 20thNight
11%4245%335%47%51%
1841
21st to endNight
12%5%35%5%345%5%6%46%
1980
October1st to 10thNight
13%8%36%6%3345%6%44%
2137
11th to 20thNight
9%9%36%43445%7%46%
2236
21st to endNight
10%11%48%6%35%45%7%36%
2574
November1st to 10thNight
12%13%49%7%3445%6%34%
2452
11th to 20thNight
8%10%49%9%6%6%5%6%8%29%
2660
21st to endNight
8%11%6%10%7%445%5%8%32%
2816
December1st to 10thNight
7%10%6%10%9%5%6%6%6%7%27%
2850
11th to 20thNight
7%13%7%12%9%5%6%5%6%6%25%
3514
21st to endNight
5%8%48%7%45%6%6%8%41%
5195

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
61%8%15%13%4
2539
11th to 20thDay
64%7%14%10%4
2540
21st to endDay
52%7%12%25%4
2794
February1st to 10thDay
62%5%11%16%6%
1550
11th to 20thDay
62%6%11%12%8%
1632
21st to endDay
56%7%12%16%8%1
1480
March1st to 10thDay
61%9%13%14%4
1800
11th to 20thDay
47%8%17%21%7%
1845
21st to endDay
53%9%16%17%5%
2372
April1st to 10thDay
41%8%15%25%10%1
2160
11th to 20thDay
53%7%14%18%7%1
2173
21st to endDay
46%7%17%23%7%1
2424
May1st to 10thDay
41%6%14%27%12%1
2520
11th to 20thDay
39%9%13%26%13%
2482
21st to endDay
49%8%13%19%10%1
2782
June1st to 10thDay
39%8%17%27%8%1
2700
11th to 20thDay
45%9%16%19%10%1
2780
21st to endDay
34%10%20%28%8%1
2880
July1st to 10thDay
26%9%20%32%12%1
2637
11th to 20thDay
28%9%19%27%17%1
2445
21st to endDay
22%9%16%35%16%2
2590
August1st to 10thDay
30%8%18%30%12%2
2491
11th to 20thDay
30%7%19%31%10%2
2477
21st to endDay
29%6%13%35%16%2
2400
September1st to 10thDay
32%6%15%29%16%2
2160
11th to 20thDay
39%6%14%28%11%3
2118
21st to endDay
36%6%12%31%14%2
1980
October1st to 10thDay
44%5%15%26%10%1
1819
11th to 20thDay
40%5%16%28%10%1
1706
21st to endDay
50%6%17%19%7%
1782
November1st to 10thDay
55%6%14%18%6%1
1625
11th to 20thDay
54%7%15%15%8%1
1520
21st to endDay
56%8%16%15%5%
1361
December1st to 10thDay
60%8%11%16%5%
1330
11th to 20thDay
61%7%17%11%3
1680
21st to endDay
38%6%12%26%16%2
2456
January1st to 10thNight
51%7%17%19%6%
4417
11th to 20thNight
60%7%16%14%4
4430
21st to endNight
49%8%19%19%4
4873
February1st to 10thNight
56%7%12%17%7%
2646
11th to 20thNight
56%6%13%16%9%1
2318
21st to endNight
47%6%15%22%10%
1776
March1st to 10thNight
52%7%17%19%5%
2160
11th to 20thNight
46%6%15%25%7%1
2111
21st to endNight
50%9%17%17%7%
1983
April1st to 10thNight
37%6%14%24%18%1
1800
11th to 20thNight
51%5%11%20%11%2
1738
21st to endNight
44%7%13%24%11%1
1534
May1st to 10thNight
37%5%14%25%17%2
1440
11th to 20thNight
35%8%12%25%18%1
1418
21st to endNight
42%8%15%21%13%1
1493
June1st to 10thNight
33%7%18%27%12%2
1260
11th to 20thNight
36%9%19%20%14%2
1172
21st to endNight
31%9%19%31%9%
1080
July1st to 10thNight
22%9%20%36%13%2
1206
11th to 20thNight
24%8%15%33%17%3
1392
21st to endNight
20%6%14%36%22%2
1488
August1st to 10thNight
26%7%17%33%16%2
1424
11th to 20thNight
24%7%17%35%16%2
1424
21st to endNight
22%6%14%32%23%2
1953
September1st to 10thNight
29%6%11%29%22%3
1800
11th to 20thNight
33%6%15%26%19%2
1841
21st to endNight
37%5%12%29%15%2
1980
October1st to 10thNight
41%5%16%26%12%1
2137
11th to 20thNight
37%5%15%29%12%1
2236
21st to endNight
47%415%24%8%1
2574
November1st to 10thNight
52%6%14%18%9%2
2452
11th to 20thNight
52%8%17%17%6%1
2660
21st to endNight
50%7%19%18%6%
2816
December1st to 10thNight
55%6%16%16%6%
2850
11th to 20thNight
59%6%14%15%6%
3516
21st to endNight
39%7%12%22%15%5%
5195

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
9%7%35%29%16%4
270
11th to 20thDay
9%10%33%34%13%1
270
21st to endDay
11%11%34%33%10%1
297
February1st to 10thDay
16%8%35%32%9%
270
11th to 20thDay
9%8%39%30%11%3
252
21st to endDay
5%6%31%36%20%2
198
March1st to 10thDay
16%7%38%26%11%2
240
11th to 20thDay
13%12%32%28%11%3
285
21st to endDay
12%14%32%27%14%2
462
April1st to 10thDay
12%14%40%27%6%1
420
11th to 20thDay
21%13%28%28%9%1
451
21st to endDay
15%10%31%28%15%1
600
May1st to 10thDay
12%9%26%33%17%3
603
11th to 20thDay
14%9%28%24%18%7%
625
21st to endDay
17%9%26%25%19%4
679
June1st to 10thDay
11%9%31%27%18%4
630
11th to 20thDay
16%10%33%26%13%2
630
21st to endDay
9%8%24%33%21%5%
630
July1st to 10thDay
8%324%38%23%3
621
11th to 20thDay
6%7%30%33%20%4
618
21st to endDay
45%29%34%19%9%
684
August1st to 10thDay
9%6%21%38%20%7%
626
11th to 20thDay
10%5%21%32%26%7%
615
21st to endDay
9%6%24%34%21%6%
519
September1st to 10thDay
13%10%30%30%14%3
450
11th to 20thDay
19%9%27%26%18%1
408
21st to endDay
19%6%29%29%17%1
270
October1st to 10thDay
21%7%29%23%18%3
270
11th to 20thDay
12%10%35%25%15%3
270
21st to endDay
18%13%35%26%7%1
297
November1st to 10thDay
23%9%31%22%14%2
270
11th to 20thDay
12%13%34%30%9%1
270
21st to endDay
10%11%34%33%11%1
270
December1st to 10thDay
13%8%33%30%12%4
270
11th to 20thDay
11%16%39%26%6%1
270
21st to endDay
11%7%32%34%14%3
297
January1st to 10thNight
8%10%37%32%12%1
950
11th to 20thNight
13%12%33%33%9%
950
21st to endNight
11%11%37%32%9%1
1045
February1st to 10thNight
13%8%33%33%12%1
936
11th to 20thNight
11%7%35%34%11%2
722
21st to endNight
6%6%28%38%19%3
592
March1st to 10thNight
11%8%33%34%12%2
720
11th to 20thNight
10%7%35%32%14%2
720
21st to endNight
14%7%29%34%15%1
597
April1st to 10thNight
9%9%35%36%10%
540
11th to 20thNight
19%7%36%31%6%1
533
21st to endNight
17%9%33%31%9%1
540
May1st to 10thNight
15%426%41%13%1
540
11th to 20thNight
15%430%36%15%1
531
21st to endNight
18%8%25%31%17%1
584
June1st to 10thNight
15%428%35%17%
540
11th to 20thNight
16%434%32%15%
452
21st to endNight
10%427%42%17%1
360
July1st to 10thNight
7%324%49%17%
424
11th to 20thNight
7%330%46%13%1
522
21st to endNight
4328%46%17%2
591
August1st to 10thNight
7%323%49%16%2
537
11th to 20thNight
8%322%42%22%2
534
21st to endNight
7%5%25%44%19%1
594
September1st to 10thNight
12%6%25%39%17%1
540
11th to 20thNight
12%431%36%16%1
540
21st to endNight
14%6%30%39%11%1
540
October1st to 10thNight
17%8%26%35%14%1
697
11th to 20thNight
14%8%28%37%12%1
796
21st to endNight
15%9%32%34%8%1
990
November1st to 10thNight
18%10%33%31%7%1
925
11th to 20thNight
13%10%37%30%9%2
950
21st to endNight
13%11%37%32%8%
950
December1st to 10thNight
12%7%34%32%12%2
950
11th to 20thNight
13%10%36%31%9%1
950
21st to endNight
13%7%33%33%12%2
1045
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