Swan Hills
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Swan Hills clear sky chart from 2005-11-05 to 2017-12-02.

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
33%
15482
10%
47645
5%
15455
37%
15455
16%
33706

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
26%
925
7%
2865
4%
925
30%
925
12%
2114
January16th to endNight
20%
889
14%
2811
6%
889
29%
889
13%
1954
February1st to 15thNight
32%
700
9%
2464
6%
697
38%
697
13%
1738
February16th to endNight
36%
632
12%
2020
10%
632
42%
632
17%
1413
March1st to 15thNight
27%
720
13%
2154
7%
720
33%
720
14%
1587
March16th to endNight
32%
768
10%
2037
5%
768
34%
768
16%
1573
April1st to 15thNight
31%
628
12%
1708
5%
628
36%
628
18%
1252
April16th to endNight
31%
482
9%
1562
8%
482
34%
482
14%
1152
May1st to 15thNight
39%
359
4%
1305
3%
359
40%
359
19%
851
May16th to endNight
39%
374
0%
1303
0%
374
39%
374
16%
923
June1st to 15thNight
36%
360
0%
1080
0%
360
36%
360
17%
805
June16th to endNight
44%
360
0%
1080
0%
360
44%
360
18%
786
July1st to 15thNight
48%
340
0%
1020
0%
340
48%
340
24%
677
July16th to endNight
51%
376
0%
1195
0%
354
51%
354
22%
777
August1st to 15thNight
60%
360
4%
1405
6%
358
61%
358
20%
855
August16th to endNight
44%
521
10%
1667
8%
521
48%
521
22%
1094
September1st to 15thNight
49%
666
13%
1770
7%
666
51%
666
32%
1131
September16th to endNight
40%
716
17%
1980
7%
716
47%
716
28%
1282
October1st to 15thNight
33%
720
12%
2179
8%
720
38%
720
18%
1544
October16th to endNight
27%
768
13%
2496
7%
768
36%
768
14%
1735
November1st to 15thNight
26%
932
12%
2762
6%
932
32%
932
14%
2013
November16th to endNight
20%
975
10%
2925
3%
975
27%
975
11%
2213
December1st to 15thNight
24%
919
11%
2785
6%
919
29%
919
13%
2040
December16th to endNight
32%
992
12%
3072
5%
992
39%
992
14%
2197

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
11%9%48%7%45%5%6%7%28%
48854
Night
8%9%47%6%36%5%6%8%32%
47779
TransparencyDay
51%8%18%16%5%
48493
Night
47%9%18%18%5%
47645
SeeingDay
18%13%30%23%10%3
6905
Night
14%13%29%27%13%2
15493

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 15thDay
39%6%11%6%37%5%7%7%29%
1074
16th to endDay
39%5%8%7%47%5%5%8%35%
1422
February1st to 15thDay
5%8%5%8%8%47%7%7%9%27%
1400
16th to endDay
311%7%11%8%445%7%10%25%
1451
March1st to 15thDay
411%6%11%7%46%6%5%8%25%
1806
16th to endDay
7%14%8%10%7%35%5%5%7%22%
2184
April1st to 15thDay
10%15%5%8%6%36%5%5%8%24%
2239
16th to endDay
14%15%47%6%35%5%47%24%
2397
May1st to 15thDay
12%10%47%7%46%5%5%7%28%
2646
16th to endDay
20%8%47%7%35%5%5%6%26%
2808
June1st to 15thDay
20%10%48%7%45%5%5%7%21%
2880
16th to endDay
16%7%48%8%36%6%5%7%25%
2880
July1st to 15thDay
14%7%25%5%35%5%7%8%33%
2880
16th to endDay
12%6%36%7%46%6%6%9%30%
2891
August1st to 15thDay
11%7%37%6%46%5%6%8%31%
2547
16th to endDay
10%5%37%7%46%6%7%9%30%
2535
September1st to 15thDay
14%8%26%5%335%5%7%36%
2187
16th to endDay
13%7%245%35%5%6%7%37%
1980
October1st to 15thDay
12%12%38%6%3445%5%31%
1778
16th to endDay
8%13%48%6%35%6%6%6%29%
1728
November1st to 15thDay
8%11%48%6%35%6%6%9%29%
1414
16th to endDay
48%410%7%46%5%5%7%34%
1365
December1st to 15thDay
5%11%6%9%8%36%5%8%9%25%
1210
16th to endDay
28%6%9%7%5%6%5%8%7%33%
1152
January1st to 15thNight
310%5%8%6%47%6%8%8%29%
2865
16th to endNight
39%48%6%36%6%7%8%34%
2811
February1st to 15thNight
48%47%7%37%7%7%8%31%
2452
16th to endNight
210%6%8%7%46%6%7%7%31%
2020
March1st to 15thNight
5%11%6%9%7%47%6%5%6%29%
2154
16th to endNight
8%12%6%10%6%36%6%7%7%23%
2034
April1st to 15thNight
11%9%5%7%6%35%5%6%6%30%
1708
16th to endNight
13%13%5%6%5%35%6%5%7%27%
1562
May1st to 15thNight
11%7%46%6%36%5%6%9%34%
1304
16th to endNight
19%8%26%435%49%7%28%
1303
June1st to 15thNight
14%10%38%7%36%5%6%7%26%
1080
16th to endNight
14%6%37%6%37%7%6%7%29%
1080
July1st to 15thNight
12%5%25%5%35%6%6%9%38%
1080
16th to endNight
10%5%24437%5%7%8%38%
1278
August1st to 15thNight
7%426%5%35%5%8%10%39%
1412
16th to endNight
11%6%26%5%345%7%9%37%
1667
September1st to 15thNight
9%7%13434448%46%
1770
16th to endNight
10%6%244345%6%8%42%
1980
October1st to 15thNight
10%11%37%5%35%5%6%7%32%
2179
16th to endNight
8%10%47%6%35%5%6%8%32%
2496
November1st to 15thNight
9%11%48%6%36%5%7%6%30%
2762
16th to endNight
5%11%6%9%7%46%5%5%7%29%
2925
December1st to 15thNight
6%10%5%8%6%45%6%6%8%31%
2785
16th to endNight
38%49%7%47%5%6%9%31%
3072

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
50%12%18%12%41
1074
16th to endDay
45%10%17%16%8%2
1422
February1st to 15thDay
49%10%20%10%7%
1400
16th to endDay
53%7%17%15%6%
1451
March1st to 15thDay
53%8%17%16%4
1806
16th to endDay
58%7%16%13%3
2185
April1st to 15thDay
56%8%14%14%5%
2239
16th to endDay
58%6%13%14%5%
2397
May1st to 15thDay
52%6%15%16%8%
2646
16th to endDay
56%7%11%14%9%
2813
June1st to 15thDay
61%7%15%14%2
2880
16th to endDay
55%8%16%14%5%
2880
July1st to 15thDay
45%9%18%20%5%
2711
16th to endDay
47%10%21%17%2
2711
August1st to 15thDay
47%10%24%15%1
2529
16th to endDay
45%10%24%15%4
2535
September1st to 15thDay
45%8%21%19%5%
2187
16th to endDay
42%8%19%20%7%
1980
October1st to 15thDay
51%7%16%19%4
1778
16th to endDay
50%8%20%18%2
1728
November1st to 15thDay
49%8%19%15%5%
1414
16th to endDay
46%10%20%16%41
1365
December1st to 15thDay
51%12%15%16%3
1210
16th to endDay
47%11%16%18%6%
1152
January1st to 15thNight
48%12%19%14%31
2865
16th to endNight
44%10%19%15%7%2
2811
February1st to 15thNight
47%11%19%14%6%1
2464
16th to endNight
49%7%16%19%6%1
2020
March1st to 15thNight
51%8%14%18%6%
2154
16th to endNight
54%8%14%15%6%
2037
April1st to 15thNight
51%6%13%19%7%1
1708
16th to endNight
54%8%11%15%9%
1562
May1st to 15thNight
44%6%17%19%11%
1305
16th to endNight
50%8%14%16%9%
1303
June1st to 15thNight
55%5%16%19%2
1080
16th to endNight
50%8%20%16%4
1080
July1st to 15thNight
39%10%21%22%5%
1020
16th to endNight
37%12%24%22%3
1195
August1st to 15thNight
36%11%26%22%2
1405
16th to endNight
39%10%24%21%4
1667
September1st to 15thNight
34%7%24%25%6%1
1770
16th to endNight
36%8%21%25%7%
1980
October1st to 15thNight
47%8%16%22%4
2179
16th to endNight
47%8%19%21%3
2496
November1st to 15thNight
51%7%17%18%4
2762
16th to endNight
52%10%16%14%41
2925
December1st to 15thNight
48%11%16%17%4
2785
16th to endNight
47%10%17%19%5%
3072

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
18%16%21%25%10%8%
60
16th to endDay
414%34%28%17%1
64
February1st to 15thDay
10%25%43%16%13
60
16th to endDay
11%15%35%25%7%4
139
March1st to 15thDay
15%25%34%17%6%
270
16th to endDay
16%17%38%21%6%
288
April1st to 15thDay
23%22%34%17%2
269
16th to endDay
31%15%32%15%4
270
May1st to 15thDay
17%16%28%22%12%2
423
16th to endDay
20%9%25%27%12%4
523
June1st to 15thDay
22%12%27%23%11%2
675
16th to endDay
17%9%30%25%13%4
675
July1st to 15thDay
16%8%29%26%16%3
645
16th to endDay
13%11%29%26%15%4
559
August1st to 15thDay
14%8%31%25%13%7%
342
16th to endDay
15%17%37%24%5%
332
September1st to 15thDay
24%13%29%22%6%3
315
16th to endDay
22%13%30%23%8%1
315
October1st to 15thDay
28%14%27%17%10%1
214
16th to endDay
20%18%25%22%10%2
144
November1st to 15thDay
21%7%36%25%44
107
16th to endDay
7%21%41%14%5%10%
90
December1st to 15thDay
9%14%33%24%11%6%
62
16th to endDay
10%10%29%18%17%12%
64
January1st to 15thNight
11%19%31%25%10%2
930
16th to endNight
14%21%33%22%7%1
889
February1st to 15thNight
10%16%29%26%13%1
704
16th to endNight
6%10%32%34%13%2
632
March1st to 15thNight
10%16%33%27%10%1
720
16th to endNight
13%11%33%27%13%1
768
April1st to 15thNight
16%12%29%29%11%
628
16th to endNight
21%9%28%27%11%1
482
May1st to 15thNight
15%12%23%30%16%1
360
16th to endNight
22%7%23%31%14%1
375
June1st to 15thNight
17%8%24%27%20%2
360
16th to endNight
16%7%21%28%23%2
360
July1st to 15thNight
15%5%22%35%21%
340
16th to endNight
12%6%23%32%20%3
376
August1st to 15thNight
9%318%35%26%5%
360
16th to endNight
14%6%25%36%15%
521
September1st to 15thNight
13%7%23%33%19%3
666
16th to endNight
12%12%29%29%14%1
716
October1st to 15thNight
16%11%29%27%12%1
720
16th to endNight
16%16%30%26%9%1
768
November1st to 15thNight
15%15%34%23%9%1
932
16th to endNight
14%17%35%20%9%1
975
December1st to 15thNight
16%17%31%24%8%3
919
16th to endNight
10%14%28%28%14%3
992
Page generated at 2017-12-03 09:16:43. Version ac04

Copyright 2017 A. Danko


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