Annapolis Royal
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Annapolis Royal 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
19%
15298
11%
47651
5%
15253
25%
15253
12%
36568

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%
743
5%
2630
2%
739
14%
739
3%
2255
January16th to endNight
7%
768
4%
2496
0%
768
11%
768
3%
2204
February1st to 15thNight
5%
704
3%
2286
0%
701
9%
701
3%
2073
February16th to endNight
13%
631
6%
2000
2%
631
17%
631
6%
1665
March1st to 15thNight
14%
720
12%
2005
4%
720
21%
720
10%
1587
March16th to endNight
16%
768
12%
2112
4%
768
22%
768
12%
1633
April1st to 15thNight
17%
584
13%
1798
5%
584
25%
584
12%
1338
April16th to endNight
22%
540
14%
1620
5%
540
29%
540
16%
1163
May1st to 15thNight
22%
540
12%
1587
5%
540
28%
540
15%
1191
May16th to endNight
22%
561
10%
1496
3%
560
29%
560
18%
1116
June1st to 15thNight
23%
426
8%
1326
4%
426
28%
426
14%
988
June16th to endNight
23%
360
9%
1260
3%
360
32%
360
14%
890
July1st to 15thNight
31%
340
10%
1190
7%
340
38%
340
21%
756
July16th to endNight
30%
542
9%
1509
7%
509
32%
509
18%
1101
August1st to 15thNight
36%
539
13%
1608
9%
535
39%
535
22%
1093
August16th to endNight
35%
573
20%
1743
12%
573
41%
573
27%
1091
September1st to 15thNight
30%
587
17%
1847
10%
587
38%
587
24%
1169
September16th to endNight
32%
717
24%
1980
12%
717
41%
717
27%
1268
October1st to 15thNight
29%
720
17%
2160
8%
720
38%
720
20%
1472
October16th to endNight
18%
768
14%
2328
5%
768
28%
768
13%
1699
November1st to 15thNight
22%
788
11%
2592
7%
788
27%
788
10%
1981
November16th to endNight
18%
825
8%
2730
4%
825
22%
825
8%
2186
December1st to 15thNight
10%
754
5%
2531
1%
754
14%
754
5%
2156
December16th to endNight
7%
800
5%
2817
1%
800
12%
800
3%
2493

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%10%47%6%34345%30%
48773
Night
19%12%5%8%6%34345%24%
47823
TransparencyDay
56%310%19%9%
48463
Night
61%410%16%7%
47651
SeeingDay
28%17%28%17%6%1
7338
Night
29%17%27%19%5%
15298

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
17%20%8%13%9%4422312%
1304
16th to endDay
16%16%7%13%13%6%5%225%10%
1728
February1st to 15thDay
18%15%8%17%15%433328%
1575
16th to endDay
12%17%7%12%9%44135%21%
1473
March1st to 15thDay
16%14%6%9%8%4332424%
1943
16th to endDay
16%12%7%8%6%3334430%
2112
April1st to 15thDay
19%12%45%5%24445%32%
2150
16th to endDay
21%9%25%423346%36%
2340
May1st to 15thDay
22%8%36%6%34445%30%
2365
16th to endDay
22%7%26%5%2435%6%31%
2618
June1st to 15thDay
25%8%25%5%34446%29%
2643
16th to endDay
21%6%35%5%3445%7%32%
2700
July1st to 15thDay
15%5%245%3446%8%40%
2700
16th to endDay
19%7%25%5%25%5%46%35%
2536
August1st to 15thDay
16%5%25%43445%5%40%
2340
16th to endDay
13%5%14423346%48%
2457
September1st to 15thDay
17%6%23322336%46%
2112
16th to endDay
16%6%24322336%47%
1980
October1st to 15thDay
20%7%23423346%41%
1800
16th to endDay
23%11%35%5%24346%29%
1894
November1st to 15thDay
21%15%47%6%34336%23%
1596
16th to endDay
20%16%7%11%6%44235%18%
1560
December1st to 15thDay
24%16%8%13%8%3223411%
1443
16th to endDay
24%19%7%15%7%233239%
1404
January1st to 15thNight
18%19%8%13%9%3323412%
2630
16th to endNight
17%16%7%16%11%5%323310%
2496
February1st to 15thNight
16%18%10%17%10%442238%
2285
16th to endNight
15%16%8%12%9%35%33417%
2000
March1st to 15thNight
18%14%49%7%35%44423%
1993
16th to endNight
19%14%7%7%5%23235%26%
2112
April1st to 15thNight
22%13%46%424447%26%
1798
16th to endNight
21%9%35%5%2435%7%30%
1620
May1st to 15thNight
23%11%36%5%23436%28%
1587
16th to endNight
21%7%35%5%35%45%7%31%
1494
June1st to 15thNight
28%7%35%42345%7%26%
1326
16th to endNight
19%6%28%6%35%5%6%8%26%
1260
July1st to 15thNight
15%5%35%435%6%7%8%34%
1260
16th to endNight
16%8%47%6%35%6%5%9%27%
1614
August1st to 15thNight
19%7%246%2446%7%35%
1620
16th to endNight
13%6%25%433448%43%
1743
September1st to 15thNight
16%6%25%32445%8%40%
1847
16th to endNight
15%6%2442445%6%43%
1980
October1st to 15thNight
18%7%36%5%2345%5%37%
2160
16th to endNight
23%11%35%423345%30%
2328
November1st to 15thNight
21%13%47%5%3445%5%24%
2592
16th to endNight
20%18%6%8%5%34335%21%
2730
December1st to 15thNight
24%15%8%11%6%34335%12%
2531
16th to endNight
26%18%9%11%8%2322311%
2817

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
79%28%7%1
1305
16th to endDay
79%35%8%2
1728
February1st to 15thDay
82%36%5%1
1578
16th to endDay
67%410%12%3
1473
March1st to 15thDay
65%28%14%7%
1954
16th to endDay
59%28%19%9%1
2112
April1st to 15thDay
55%37%18%13%1
2150
16th to endDay
50%210%21%13%1
2340
May1st to 15thDay
56%38%19%10%1
2365
16th to endDay
52%412%21%7%
2622
June1st to 15thDay
56%49%19%8%1
2643
16th to endDay
51%412%19%10%
2700
July1st to 15thDay
40%416%24%12%1
2541
16th to endDay
48%5%13%23%8%
2379
August1st to 15thDay
45%412%23%13%
2327
16th to endDay
37%316%29%14%
2457
September1st to 15thDay
40%311%27%14%1
2112
16th to endDay
40%29%30%15%1
1980
October1st to 15thDay
44%411%27%11%
1800
16th to endDay
56%310%21%8%
1894
November1st to 15thDay
63%310%15%5%
1596
16th to endDay
70%39%11%3
1560
December1st to 15thDay
78%38%7%1
1443
16th to endDay
80%37%6%2
1404
January1st to 15thNight
76%39%9%1
2630
16th to endNight
80%37%8%1
2496
February1st to 15thNight
83%36%5%2
2286
16th to endNight
71%39%10%4
2000
March1st to 15thNight
63%38%15%6%
2005
16th to endNight
61%38%16%10%
2112
April1st to 15thNight
58%38%16%11%1
1798
16th to endNight
54%39%19%12%1
1620
May1st to 15thNight
56%310%19%7%
1587
16th to endNight
52%6%13%19%7%
1496
June1st to 15thNight
56%5%12%19%41
1326
16th to endNight
52%7%12%18%9%
1260
July1st to 15thNight
41%7%18%21%9%
1190
16th to endNight
51%6%14%19%6%
1509
August1st to 15thNight
46%414%24%9%
1608
16th to endNight
39%416%28%11%
1743
September1st to 15thNight
41%5%11%29%12%
1847
16th to endNight
40%310%27%17%1
1980
October1st to 15thNight
48%310%24%12%1
2160
16th to endNight
56%310%21%8%
2328
November1st to 15thNight
60%5%11%15%6%
2592
16th to endNight
66%5%12%11%3
2730
December1st to 15thNight
74%49%10%1
2531
16th to endNight
79%36%7%2
2817

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
40%20%31%6%
72
16th to endDay
29%27%29%10%2
256
February1st to 15thDay
26%29%30%12%
236
16th to endDay
23%27%26%16%4
221
March1st to 15thDay
30%27%27%11%3
270
16th to endDay
31%26%25%10%5%1
288
April1st to 15thDay
33%26%23%12%2
270
16th to endDay
25%22%29%14%6%
270
May1st to 15thDay
30%18%28%15%5%1
321
16th to endDay
33%15%26%18%5%1
519
June1st to 15thDay
34%13%26%19%5%
495
16th to endDay
31%11%32%16%6%1
495
July1st to 15thDay
22%8%35%20%11%1
475
16th to endDay
25%7%33%26%6%
388
August1st to 15thDay
20%9%37%22%8%1
313
16th to endDay
17%11%28%27%12%2
332
September1st to 15thDay
21%13%37%19%7%1
315
16th to endDay
22%12%28%23%7%4
314
October1st to 15thDay
28%12%24%21%8%4
270
16th to endDay
36%22%21%13%41
288
November1st to 15thDay
33%18%23%17%5%1
280
16th to endDay
33%22%26%10%5%1
285
December1st to 15thDay
36%29%20%11%2
241
16th to endDay
38%32%19%8%
124
January1st to 15thNight
34%26%23%13%2
743
16th to endNight
33%26%25%11%2
768
February1st to 15thNight
32%25%29%10%1
704
16th to endNight
30%23%26%15%3
631
March1st to 15thNight
31%21%27%16%2
720
16th to endNight
30%22%25%17%4
768
April1st to 15thNight
34%17%27%17%3
584
16th to endNight
28%15%30%19%5%
540
May1st to 15thNight
30%14%28%19%6%
540
16th to endNight
24%13%34%22%4
561
June1st to 15thNight
32%8%29%23%5%
426
16th to endNight
21%9%39%20%8%
360
July1st to 15thNight
17%6%39%27%8%
340
16th to endNight
21%9%30%32%6%
542
August1st to 15thNight
23%6%26%31%11%
539
16th to endNight
16%8%34%28%10%1
573
September1st to 15thNight
20%9%35%26%8%
587
16th to endNight
20%9%31%23%11%1
717
October1st to 15thNight
23%12%28%24%9%1
720
16th to endNight
32%22%23%15%6%
768
November1st to 15thNight
29%17%23%20%7%1
788
16th to endNight
33%20%23%16%6%
825
December1st to 15thNight
38%22%24%12%2
754
16th to endNight
39%27%19%10%2
800
Page generated at 2017-12-02 10:14:23. Version ac04

Copyright 2017 A. Danko


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