Swan Hills
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Swan Hills clear sky chart from 2005-11-06 to 2024-02-10.

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
31%
23701
11%
80783
5%
23603
37%
23603
16%
54319

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
25%
1027
12%
4985
4%
1006
31%
1006
8%
3399
January11th to 20thNight
22%
984
20%
4737
4%
970
30%
970
10%
2925
January21st to endNight
19%
924
9%
4994
5%
909
28%
909
7%
3121
February1st to 10thNight
29%
758
11%
2652
7%
758
35%
758
12%
1882
February11th to 20thNight
27%
702
12%
2410
7%
700
36%
700
13%
1690
February21st to endNight
33%
592
16%
1826
10%
592
42%
592
18%
1274
March1st to 10thNight
29%
720
14%
2160
9%
720
35%
720
16%
1549
March11th to 20thNight
31%
720
15%
2062
8%
720
36%
720
18%
1455
March21st to endNight
32%
792
12%
2066
6%
792
34%
792
18%
1563
April1st to 10thNight
33%
674
13%
1754
5%
674
37%
674
21%
1244
April11th to 20thNight
30%
533
14%
1601
9%
533
37%
533
17%
1133
April21st to endNight
31%
454
10%
1534
8%
454
36%
454
16%
1078
May1st to 10thNight
38%
360
5%
1328
4%
360
40%
360
17%
889
May11th to 20thNight
39%
354
2%
1239
1%
354
40%
354
21%
799
May21st to endNight
40%
388
0%
1350
0%
388
40%
388
19%
904
June1st to 10thNight
40%
360
0%
1080
0%
360
40%
360
19%
776
June11th to 20thNight
39%
360
0%
1080
0%
360
39%
360
15%
824
June21st to endNight
47%
360
0%
1080
0%
360
47%
360
21%
751
July1st to 10thNight
47%
350
0%
1050
0%
350
47%
350
23%
704
July11th to 20thNight
41%
348
0%
1066
0%
348
41%
348
21%
738
July21st to endNight
51%
394
1%
1302
0%
372
51%
372
23%
812
August1st to 10thNight
54%
358
5%
1382
6%
356
56%
356
20%
855
August11th to 20thNight
49%
365
11%
1433
12%
365
55%
365
22%
838
August21st to endNight
43%
594
13%
1782
9%
594
47%
594
23%
1182
September1st to 10thNight
43%
639
13%
1719
6%
639
46%
639
27%
1128
September11th to 20thNight
39%
720
15%
1926
7%
720
45%
720
28%
1280
September21st to endNight
37%
720
18%
1980
8%
720
44%
720
24%
1317
October1st to 10thNight
34%
720
12%
2097
8%
720
38%
720
20%
1452
October11th to 20thNight
28%
720
16%
2340
7%
720
39%
720
18%
1527
October21st to endNight
21%
792
14%
2574
5%
792
32%
792
12%
1821
November1st to 10thNight
26%
897
13%
2642
7%
897
32%
897
14%
1941
November11th to 20thNight
19%
950
12%
2850
3%
950
28%
950
11%
2117
November21st to endNight
19%
950
10%
2850
3%
950
26%
950
13%
2059
December1st to 10thNight
23%
950
16%
2850
5%
950
33%
950
16%
1929
December11th to 20thNight
25%
1037
12%
3700
4%
1036
32%
1036
12%
2607
December21st to endNight
29%
1135
10%
5302
6%
1114
36%
1114
13%
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%9%48%7%46%6%7%8%31%
77456
Night
7%9%48%7%46%6%7%8%34%
81451
TransparencyDay
48%9%18%18%7%
77144
Night
45%9%17%20%8%1
81342
SeeingDay
18%16%31%23%10%3
15164
Night
14%15%31%27%12%2
23745

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
29%6%12%13%5%8%7%8%8%23%
1899
11th to 20thDay
28%49%7%46%7%8%10%36%
2023
21st to endDay
38%47%7%5%6%6%7%8%38%
2663
February1st to 10thDay
5%8%5%10%8%6%7%7%9%9%26%
1512
11th to 20thDay
39%5%10%8%46%5%8%11%29%
1438
21st to endDay
39%7%11%10%45%6%7%10%27%
1426
March1st to 10thDay
411%6%13%8%6%7%6%6%8%26%
1800
11th to 20thDay
6%10%6%9%8%36%6%6%8%32%
1897
21st to endDay
6%17%8%11%8%35%6%6%6%24%
2286
April1st to 10thDay
8%14%6%11%9%5%6%5%6%7%24%
2205
11th to 20thDay
9%14%5%7%8%35%6%6%8%27%
2310
21st to endDay
13%14%48%7%36%5%6%8%26%
2425
May1st to 10thDay
13%13%48%8%46%6%6%7%26%
2632
11th to 20thDay
12%6%48%7%45%6%6%8%34%
2654
21st to endDay
18%9%46%7%45%5%6%7%30%
2924
June1st to 10thDay
18%9%48%7%46%6%6%7%27%
2880
11th to 20thDay
22%10%5%8%8%45%6%6%7%19%
2880
21st to endDay
12%8%37%8%46%7%6%8%31%
2880
July1st to 10thDay
15%8%36%5%46%6%7%8%32%
2880
11th to 20thDay
14%7%37%7%46%6%8%8%30%
2858
21st to endDay
10%6%36%6%46%6%8%9%35%
2938
August1st to 10thDay
11%7%37%7%5%7%6%7%9%32%
2548
11th to 20thDay
9%6%36%6%46%6%6%9%38%
2465
21st to endDay
13%6%37%7%46%6%7%9%33%
2574
September1st to 10thDay
13%8%37%5%346%5%8%37%
2237
11th to 20thDay
14%10%25%5%345%6%7%37%
2034
21st to endDay
10%7%45%6%35%6%7%8%38%
1980
October1st to 10thDay
10%13%39%6%35%5%6%7%35%
1861
11th to 20thDay
9%11%5%8%6%35%5%7%7%34%
1620
21st to endDay
8%14%5%10%7%36%6%6%7%30%
1782
November1st to 10thDay
8%12%410%7%46%6%6%9%29%
1418
11th to 20thDay
5%9%49%7%45%5%7%9%34%
1330
21st to endDay
37%411%9%5%7%5%6%8%34%
1330
December1st to 10thDay
48%5%8%8%46%6%7%9%35%
1330
11th to 20thDay
5%9%6%9%6%47%6%7%9%32%
1447
21st to endDay
36%35%6%35%5%8%11%46%
2090
January1st to 10thNight
28%411%11%5%7%6%6%8%31%
5046
11th to 20thNight
27%48%8%5%7%8%8%8%36%
4861
21st to endNight
410%5%9%6%47%6%7%9%33%
5022
February1st to 10thNight
49%410%9%5%7%7%8%9%28%
2652
11th to 20thNight
38%5%10%9%46%7%9%9%31%
2408
21st to endNight
29%6%9%9%5%7%7%8%7%32%
1826
March1st to 10thNight
410%5%10%10%5%8%6%6%7%31%
2160
11th to 20thNight
6%9%5%8%7%5%7%7%7%8%32%
2062
21st to endNight
7%15%7%10%6%46%5%6%8%26%
2066
April1st to 10thNight
7%9%5%7%8%5%6%6%7%8%32%
1754
11th to 20thNight
10%12%5%7%6%46%6%6%6%32%
1601
21st to endNight
12%11%6%7%6%35%6%6%8%31%
1534
May1st to 10thNight
11%11%46%6%36%6%7%10%30%
1328
11th to 20thNight
11%7%46%5%46%5%7%8%38%
1239
21st to endNight
16%7%36%5%46%5%7%8%32%
1350
June1st to 10thNight
14%7%38%7%46%6%7%6%31%
1080
11th to 20thNight
17%10%48%6%5%6%7%6%9%23%
1080
21st to endNight
10%7%36%7%36%7%8%8%35%
1080
July1st to 10thNight
12%8%26%5%36%5%7%9%38%
1080
11th to 20thNight
12%7%36%6%46%5%6%8%37%
1102
21st to endNight
10%6%26%5%36%6%8%9%40%
1379
August1st to 10thNight
9%5%35%6%46%5%7%10%40%
1389
11th to 20thNight
8%7%35%5%345%7%10%43%
1433
21st to endNight
12%7%26%6%345%7%8%39%
1782
September1st to 10thNight
11%6%25%6%46%5%5%8%43%
1719
11th to 20thNight
12%9%35%5%345%5%8%43%
1926
21st to endNight
8%8%35%6%45%5%6%8%41%
1980
October1st to 10thNight
9%10%39%6%45%6%6%7%35%
2097
11th to 20thNight
7%10%5%6%5%35%6%7%8%38%
2340
21st to endNight
8%10%5%9%8%5%6%5%5%7%32%
2574
November1st to 10thNight
10%14%5%9%7%35%5%6%7%30%
2642
11th to 20thNight
5%10%5%10%9%5%8%6%7%8%29%
2850
21st to endNight
5%10%5%8%7%6%6%6%6%8%32%
2850
December1st to 10thNight
48%48%7%5%6%7%7%9%36%
2850
11th to 20thNight
6%11%49%6%46%6%7%9%32%
3743
21st to endNight
25%36%7%37%6%7%10%45%
5566

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
54%9%16%14%6%1
1899
11th to 20thDay
39%9%14%12%23%3
2042
21st to endDay
39%10%27%15%8%1
2663
February1st to 10thDay
49%11%18%13%9%1
1512
11th to 20thDay
48%9%18%18%8%
1446
21st to endDay
51%7%16%17%8%1
1426
March1st to 10thDay
53%8%18%17%6%
1800
11th to 20thDay
48%7%15%21%8%1
1898
21st to endDay
58%8%17%12%5%
2286
April1st to 10thDay
57%8%15%14%7%
2205
11th to 20thDay
52%7%16%17%7%
2310
21st to endDay
53%8%13%19%6%1
2425
May1st to 10thDay
55%7%14%15%7%
2632
11th to 20thDay
45%7%13%23%12%
2658
21st to endDay
52%7%13%18%10%1
2925
June1st to 10thDay
54%8%15%18%5%
2880
11th to 20thDay
63%8%12%15%3
2880
21st to endDay
48%9%19%18%7%
2880
July1st to 10thDay
46%9%16%21%6%1
2801
11th to 20thDay
49%11%20%18%2
2771
21st to endDay
40%11%24%22%3
2775
August1st to 10thDay
45%11%23%18%2
2530
11th to 20thDay
40%9%23%22%6%
2465
21st to endDay
45%10%22%18%5%
2574
September1st to 10thDay
43%8%20%22%6%1
2237
11th to 20thDay
43%7%22%21%6%
2034
21st to endDay
41%10%17%23%9%
1980
October1st to 10thDay
48%8%19%18%8%
1861
11th to 20thDay
45%9%18%23%5%1
1620
21st to endDay
51%9%17%17%6%
1782
November1st to 10thDay
51%9%16%18%6%1
1418
11th to 20thDay
44%9%23%16%7%
1330
21st to endDay
46%12%18%18%6%2
1330
December1st to 10thDay
43%11%17%19%9%1
1330
11th to 20thDay
47%10%16%21%6%
1449
21st to endDay
31%8%16%26%18%1
2090
January1st to 10thNight
49%10%14%19%7%2
5046
11th to 20thNight
41%9%13%13%19%4
4903
21st to endNight
44%10%24%14%7%1
5022
February1st to 10thNight
50%9%15%15%9%1
2652
11th to 20thNight
46%11%17%17%8%1
2410
21st to endNight
48%7%14%21%8%1
1826
March1st to 10thNight
49%8%15%20%7%1
2160
11th to 20thNight
46%8%14%19%12%
2062
21st to endNight
53%8%14%19%6%1
2066
April1st to 10thNight
46%7%15%21%10%1
1754
11th to 20thNight
50%7%12%20%10%2
1601
21st to endNight
50%8%12%19%10%1
1534
May1st to 10thNight
47%7%19%18%9%
1328
11th to 20thNight
42%8%13%24%12%1
1239
21st to endNight
46%7%16%19%12%
1350
June1st to 10thNight
49%8%16%19%8%
1080
11th to 20thNight
56%8%14%20%1
1080
21st to endNight
43%10%22%18%6%
1080
July1st to 10thNight
40%11%19%21%8%1
1050
11th to 20thNight
44%10%23%21%2
1066
21st to endNight
36%11%24%26%3
1302
August1st to 10thNight
38%11%26%23%3
1382
11th to 20thNight
33%11%23%26%6%
1433
21st to endNight
41%9%21%23%6%
1782
September1st to 10thNight
37%9%22%25%6%2
1719
11th to 20thNight
39%7%20%27%7%
1926
21st to endNight
38%8%18%25%10%1
1980
October1st to 10thNight
45%8%16%22%8%
2097
11th to 20thNight
41%8%19%24%7%
2340
21st to endNight
50%8%16%19%7%1
2574
November1st to 10thNight
53%7%15%20%5%
2642
11th to 20thNight
52%10%15%15%7%1
2850
21st to endNight
48%10%19%17%5%1
2850
December1st to 10thNight
43%9%16%21%10%2
2850
11th to 20thNight
48%9%18%17%7%
3740
21st to endNight
32%8%17%28%13%2
5566

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
10%17%37%21%10%4
180
11th to 20thDay
17%19%31%17%13%3
180
21st to endDay
16%22%30%20%9%2
198
February1st to 10thDay
16%21%39%17%5%2
178
11th to 20thDay
15%23%37%15%7%3
178
21st to endDay
8%22%36%24%8%3
292
March1st to 10thDay
14%22%31%25%9%
420
11th to 20thDay
10%22%37%20%6%4
420
21st to endDay
15%20%35%22%8%
462
April1st to 10thDay
17%23%35%18%5%2
420
11th to 20thDay
19%21%28%19%9%3
412
21st to endDay
20%20%35%21%4
420
May1st to 10thDay
20%18%31%20%9%2
535
11th to 20thDay
15%12%32%26%13%2
625
21st to endDay
19%13%25%28%11%4
686
June1st to 10thDay
21%15%30%24%9%1
810
11th to 20thDay
27%10%26%24%11%3
810
21st to endDay
16%10%27%26%16%5%
810
July1st to 10thDay
17%11%28%26%15%3
796
11th to 20thDay
16%14%29%25%13%4
770
21st to endDay
13%8%28%29%15%6%
684
August1st to 10thDay
17%9%30%23%14%7%
488
11th to 20thDay
14%16%36%24%8%2
437
21st to endDay
17%15%31%25%8%3
495
September1st to 10thDay
26%18%28%16%10%3
450
11th to 20thDay
24%13%31%22%9%2
450
21st to endDay
18%24%28%20%8%2
450
October1st to 10thDay
22%18%29%19%10%1
391
11th to 20thDay
22%18%30%20%8%1
270
21st to endDay
25%23%28%17%6%1
297
November1st to 10thDay
16%22%34%19%6%3
232
11th to 20thDay
16%24%33%16%8%3
180
21st to endDay
13%26%33%19%6%3
180
December1st to 10thDay
13%27%34%14%8%4
180
11th to 20thDay
15%20%37%21%6%1
180
21st to endDay
10%20%27%25%12%6%
198
January1st to 10thNight
11%21%33%24%10%1
1040
11th to 20thNight
13%19%36%23%9%1
996
21st to endNight
17%24%29%21%7%1
931
February1st to 10thNight
13%19%28%25%13%2
758
11th to 20thNight
10%18%36%25%11%1
704
21st to endNight
8%13%34%32%10%4
592
March1st to 10thNight
9%16%34%27%11%2
720
11th to 20thNight
9%17%33%28%10%2
720
21st to endNight
13%12%34%27%12%2
792
April1st to 10thNight
10%12%34%28%14%1
674
11th to 20thNight
17%13%30%27%12%2
533
21st to endNight
18%11%31%26%13%1
454
May1st to 10thNight
17%10%25%31%15%2
360
11th to 20thNight
16%7%30%30%16%1
354
21st to endNight
17%10%28%29%15%2
389
June1st to 10thNight
18%10%23%32%17%1
360
11th to 20thNight
22%9%20%28%18%2
360
21st to endNight
13%8%21%34%21%4
360
July1st to 10thNight
15%7%23%34%22%
350
11th to 20thNight
16%8%27%27%20%2
348
21st to endNight
11%7%23%35%21%4
394
August1st to 10thNight
11%5%21%36%22%5%
358
11th to 20thNight
12%9%24%35%20%1
365
21st to endNight
18%7%23%34%16%1
594
September1st to 10thNight
17%9%24%32%16%2
639
11th to 20thNight
16%11%26%31%15%1
720
21st to endNight
13%16%28%30%12%1
720
October1st to 10thNight
18%12%30%28%10%1
720
11th to 20thNight
13%16%31%29%10%1
720
21st to endNight
20%20%29%23%7%
792
November1st to 10thNight
19%15%32%24%8%1
897
11th to 20thNight
13%22%35%21%7%2
950
21st to endNight
14%22%37%19%7%1
950
December1st to 10thNight
13%20%33%22%9%3
950
11th to 20thNight
13%20%34%24%8%1
1037
21st to endNight
9%16%34%27%12%2
1144
Page generated at 2024-02-07 04:11:56. Version ac07

Copyright 2024 Attilla Danko


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