Antigonish
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Antigonish clear sky chart from 2005-11-05 to 2017-12-01.

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
22%
15605
9%
47808
5%
15561
26%
15561
12%
36820

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
9%
749
6%
2506
0%
746
15%
746
7%
2034
January16th to endNight
12%
787
8%
2607
1%
787
19%
787
8%
2058
February1st to 15thNight
15%
704
7%
2286
2%
701
20%
701
8%
1804
February16th to endNight
15%
631
6%
1985
2%
631
20%
631
8%
1613
March1st to 15thNight
18%
717
11%
2059
5%
717
24%
717
12%
1631
March16th to endNight
21%
720
12%
2064
5%
720
27%
720
13%
1599
April1st to 15thNight
18%
539
10%
1796
6%
539
24%
539
11%
1362
April16th to endNight
24%
540
14%
1698
8%
540
30%
540
15%
1240
May1st to 15thNight
25%
540
11%
1440
5%
540
28%
540
14%
1127
May16th to endNight
22%
561
10%
1496
4%
560
26%
560
17%
1130
June1st to 15thNight
21%
540
5%
1440
2%
540
23%
540
14%
1160
June16th to endNight
29%
540
7%
1440
3%
540
32%
540
18%
1100
July1st to 15thNight
40%
510
9%
1360
5%
510
42%
510
26%
939
July16th to endNight
41%
565
10%
1419
8%
532
42%
532
19%
1065
August1st to 15thNight
41%
539
11%
1552
8%
535
42%
535
20%
1119
August16th to endNight
45%
573
13%
1830
10%
573
49%
573
21%
1216
September1st to 15thNight
33%
540
14%
1800
11%
540
40%
540
21%
1202
September16th to endNight
32%
622
18%
1974
12%
622
39%
622
20%
1326
October1st to 15thNight
24%
720
14%
2160
6%
720
30%
720
18%
1546
October16th to endNight
16%
784
10%
2367
4%
784
21%
784
11%
1845
November1st to 15thNight
19%
805
8%
2580
4%
805
22%
805
10%
2034
November16th to endNight
16%
825
8%
2730
4%
825
22%
825
8%
2168
December1st to 15thNight
10%
754
5%
2531
0%
754
15%
754
5%
2177
December16th to endNight
7%
800
3%
2688
0%
800
11%
800
4%
2325

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
19%11%48%6%34446%25%
48619
Night
18%10%48%6%35%446%25%
47980
TransparencyDay
59%6%11%15%7%
48309
Night
58%7%12%15%6%
47808
SeeingDay
24%15%30%20%6%1
7920
Night
24%16%31%21%6%
15609

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
14%15%6%11%8%46%5%5%5%16%
1432
16th to endDay
15%12%6%11%10%5%7%435%17%
1614
February1st to 15thDay
16%11%6%10%8%45%445%21%
1575
16th to endDay
10%17%7%9%8%36%5%45%21%
1487
March1st to 15thDay
13%15%5%9%7%45%5%5%5%22%
1888
16th to endDay
15%15%9%9%8%3332425%
2160
April1st to 15thDay
18%12%6%7%6%34345%26%
2153
16th to endDay
23%12%35%433446%26%
2262
May1st to 15thDay
24%9%46%5%34346%25%
2512
16th to endDay
21%10%46%43445%6%27%
2618
June1st to 15thDay
30%9%35%5%34447%21%
2520
16th to endDay
22%9%47%6%245%5%6%26%
2520
July1st to 15thDay
15%5%26%6%25%5%6%9%34%
2520
16th to endDay
17%8%36%7%36%6%6%6%26%
2653
August1st to 15thDay
20%8%35%5%3445%7%29%
2394
16th to endDay
16%7%25%5%3446%8%36%
2370
September1st to 15thDay
19%7%36%6%3435%5%34%
2160
16th to endDay
17%7%345%3446%7%34%
1983
October1st to 15thDay
19%7%38%5%35%5%5%7%28%
1800
16th to endDay
23%12%49%8%35%436%19%
1855
November1st to 15thDay
21%15%5%8%6%33445%21%
1604
16th to endDay
16%15%6%11%8%345%5%417%
1560
December1st to 15thDay
20%16%6%13%9%46%4349%
1443
16th to endDay
20%15%9%13%10%5%5%3339%
1536
January1st to 15thNight
14%13%7%11%8%5%6%445%18%
2506
16th to endNight
15%11%7%9%8%5%6%445%20%
2607
February1st to 15thNight
16%13%5%10%8%46%445%21%
2285
16th to endNight
12%14%8%11%9%46%44319%
1985
March1st to 15thNight
16%12%7%10%6%35%45%5%22%
2047
16th to endNight
18%12%6%8%7%3434427%
2064
April1st to 15thNight
19%12%47%6%44445%26%
1796
16th to endNight
24%9%245%35%346%30%
1698
May1st to 15thNight
27%10%36%42335%427%
1440
16th to endNight
16%11%47%42445%8%28%
1494
June1st to 15thNight
26%8%37%6%35%35%5%23%
1440
16th to endNight
21%6%26%6%245%48%31%
1440
July1st to 15thNight
12%425%5%25%5%7%11%36%
1440
16th to endNight
16%6%25%5%36%7%6%9%29%
1515
August1st to 15thNight
17%6%45%6%35%46%8%32%
1563
16th to endNight
14%5%25%5%35%5%410%37%
1830
September1st to 15thNight
16%6%25%42446%8%37%
1800
16th to endNight
17%6%26%5%335%5%8%36%
1974
October1st to 15thNight
21%7%26%6%35%45%6%33%
2160
16th to endNight
24%10%36%6%34436%24%
2367
November1st to 15thNight
20%12%48%7%345%5%6%22%
2580
16th to endNight
18%13%5%9%6%35%6%5%6%18%
2730
December1st to 15thNight
20%14%6%11%9%5%6%44412%
2531
16th to endNight
23%16%6%10%9%45%43410%
2688

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
65%7%12%9%4
1433
16th to endDay
66%6%10%10%5%
1614
February1st to 15thDay
64%5%11%12%5%
1578
16th to endDay
63%5%11%11%6%1
1487
March1st to 15thDay
62%5%10%13%7%
1899
16th to endDay
64%38%15%6%1
2160
April1st to 15thDay
60%5%8%11%11%2
2153
16th to endDay
59%5%10%15%8%
2262
May1st to 15thDay
60%6%8%16%7%
2512
16th to endDay
56%7%9%19%6%
2622
June1st to 15thDay
62%6%11%12%5%
2520
16th to endDay
58%7%9%15%8%
2520
July1st to 15thDay
45%9%14%20%9%
2372
16th to endDay
56%8%11%17%5%
2486
August1st to 15thDay
53%8%10%19%6%
2380
16th to endDay
45%7%14%23%9%
2370
September1st to 15thDay
51%6%11%20%9%
2160
16th to endDay
46%7%10%23%11%
1983
October1st to 15thDay
53%6%13%17%8%
1800
16th to endDay
65%6%10%12%4
1855
November1st to 15thDay
63%5%13%11%5%
1604
16th to endDay
66%7%13%8%4
1560
December1st to 15thDay
74%8%10%5%1
1443
16th to endDay
75%6%8%6%2
1536
January1st to 15thNight
66%6%13%9%3
2506
16th to endNight
63%6%12%13%4
2607
February1st to 15thNight
64%5%12%11%6%
2286
16th to endNight
66%6%9%12%4
1985
March1st to 15thNight
63%49%15%7%
2059
16th to endNight
60%49%16%8%1
2064
April1st to 15thNight
59%5%9%13%10%1
1796
16th to endNight
54%5%9%16%12%1
1698
May1st to 15thNight
60%5%9%18%6%
1440
16th to endNight
54%7%11%20%6%
1496
June1st to 15thNight
60%7%9%15%5%
1440
16th to endNight
52%9%10%16%9%
1440
July1st to 15thNight
39%11%16%21%11%
1360
16th to endNight
48%11%13%19%5%
1419
August1st to 15thNight
48%8%14%22%5%
1552
16th to endNight
40%11%17%22%7%
1830
September1st to 15thNight
43%7%12%25%9%
1800
16th to endNight
44%7%13%24%9%
1974
October1st to 15thNight
50%6%13%20%8%
2160
16th to endNight
59%7%11%16%5%
2367
November1st to 15thNight
60%8%13%12%4
2580
16th to endNight
61%9%14%10%4
2730
December1st to 15thNight
71%7%11%7%1
2531
16th to endNight
75%5%10%5%2
2688

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
20%26%35%15%1
240
16th to endDay
23%22%35%15%1
256
February1st to 15thDay
22%26%31%16%2
236
16th to endDay
21%22%30%18%6%
212
March1st to 15thDay
19%22%36%13%7%
257
16th to endDay
28%24%26%13%41
288
April1st to 15thDay
27%20%31%16%4
270
16th to endDay
26%19%28%17%6%1
270
May1st to 15thDay
30%13%27%17%7%3
468
16th to endDay
27%10%34%22%41
519
June1st to 15thDay
33%11%30%19%5%
495
16th to endDay
25%9%33%22%7%1
495
July1st to 15thDay
16%434%34%9%1
475
16th to endDay
22%7%28%26%13%1
514
August1st to 15thDay
23%5%26%29%10%4
367
16th to endDay
19%9%29%25%12%3
332
September1st to 15thDay
22%10%30%28%7%
315
16th to endDay
21%9%30%25%10%2
291
October1st to 15thDay
22%15%25%24%8%3
270
16th to endDay
26%21%31%12%6%
288
November1st to 15thDay
25%18%29%19%42
280
16th to endDay
24%25%28%15%4
285
December1st to 15thDay
34%22%28%13%1
241
16th to endDay
28%24%34%10%1
256
January1st to 15thNight
23%22%36%14%2
750
16th to endNight
23%24%32%15%3
787
February1st to 15thNight
26%18%33%18%2
704
16th to endNight
22%22%31%18%5%
631
March1st to 15thNight
22%19%31%21%5%
720
16th to endNight
25%17%29%20%5%
720
April1st to 15thNight
25%18%30%20%3
539
16th to endNight
29%13%28%23%4
540
May1st to 15thNight
33%12%24%19%8%1
540
16th to endNight
22%12%39%18%5%
561
June1st to 15thNight
29%8%33%23%4
540
16th to endNight
24%7%33%28%5%
540
July1st to 15thNight
15%436%33%9%
510
16th to endNight
19%6%28%33%11%
565
August1st to 15thNight
20%427%32%14%
539
16th to endNight
17%7%24%40%9%
573
September1st to 15thNight
18%7%34%28%10%
540
16th to endNight
22%11%30%26%9%
622
October1st to 15thNight
23%12%34%20%8%
720
16th to endNight
27%20%29%16%5%
784
November1st to 15thNight
26%19%30%15%6%1
805
16th to endNight
25%25%26%17%4
825
December1st to 15thNight
30%23%30%11%3
754
16th to endNight
32%24%29%10%21
800
Page generated at 2017-12-02 10:14:26. Version ac04

Copyright 2017 A. Danko


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