This page made possible by the sponsorship of: Tim Kearsley.

Annapolis Royal
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Annapolis Royal clear sky chart from 2005-11-06 to 2024-01-15.

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
18%
23465
11%
74696
5%
23400
25%
23400
11%
57318

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
8%
850
5%
2838
2%
847
12%
847
3%
2506
January11th to 20thNight
7%
754
4%
2506
1%
754
11%
754
3%
2203
January21st to endNight
8%
792
5%
2574
1%
792
12%
792
4%
2223
February1st to 10thNight
6%
720
5%
2340
1%
720
11%
720
3%
2072
February11th to 20thNight
7%
703
6%
2276
1%
700
13%
700
4%
1979
February21st to endNight
12%
592
9%
1848
2%
592
19%
592
7%
1462
March1st to 10thNight
10%
720
12%
2017
3%
720
18%
720
8%
1616
March11th to 20thNight
15%
720
10%
1980
3%
720
22%
720
10%
1569
March21st to endNight
15%
792
14%
2178
3%
792
24%
792
12%
1658
April1st to 10thNight
13%
608
11%
1868
3%
608
21%
608
10%
1420
April11th to 20thNight
17%
534
16%
1625
5%
534
27%
534
14%
1167
April21st to endNight
21%
540
13%
1620
5%
540
28%
540
14%
1189
May1st to 10thNight
21%
540
14%
1620
6%
540
28%
540
16%
1167
May11th to 20thNight
22%
532
17%
1457
6%
532
33%
532
17%
1056
May21st to endNight
21%
583
11%
1551
4%
582
27%
582
19%
1131
June1st to 10thNight
23%
461
11%
1361
5%
461
29%
461
16%
983
June11th to 20thNight
27%
360
14%
1260
6%
360
38%
360
18%
833
June21st to endNight
22%
360
8%
1260
4%
360
29%
360
14%
910
July1st to 10thNight
26%
350
11%
1225
5%
350
36%
350
19%
803
July11th to 20thNight
30%
402
11%
1272
8%
402
36%
402
17%
892
July21st to endNight
30%
590
11%
1663
7%
558
34%
558
20%
1177
August1st to 10thNight
32%
538
14%
1600
9%
534
35%
534
25%
1036
August11th to 20thNight
34%
532
14%
1596
9%
532
38%
532
21%
1099
August21st to endNight
34%
594
19%
1818
10%
594
41%
594
25%
1160
September1st to 10thNight
32%
540
19%
1800
10%
540
43%
540
24%
1095
September11th to 20thNight
34%
700
21%
1960
11%
700
43%
700
26%
1263
September21st to endNight
28%
720
22%
1980
9%
720
38%
720
24%
1331
October1st to 10thNight
32%
720
18%
2159
9%
720
40%
720
22%
1450
October11th to 20thNight
23%
720
18%
2160
6%
720
34%
720
18%
1479
October21st to endNight
16%
792
14%
2412
5%
792
25%
792
11%
1830
November1st to 10thNight
18%
778
13%
2487
5%
778
26%
778
11%
1841
November11th to 20thNight
17%
850
10%
2660
6%
850
22%
850
8%
2142
November21st to endNight
14%
850
6%
2660
2%
850
19%
850
7%
2159
December1st to 10thNight
8%
850
5%
2660
1%
850
13%
850
5%
2306
December11th to 20thNight
6%
850
5%
3236
2%
849
9%
849
2%
2848
December21st to endNight
7%
928
3%
5169
1%
907
13%
907
2%
4263

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%7%34446%31%
74803
Night
20%13%5%9%7%34446%25%
74973
TransparencyDay
56%411%19%10%1
74507
Night
61%410%16%7%1
74804
SeeingDay
31%19%30%15%41
15574
Night
31%18%28%18%5%
23472

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 10thDay
17%21%9%14%11%45%22412%
1327
11th to 20thDay
22%18%8%13%10%6%423410%
1553
21st to endDay
12%14%7%16%17%6%5%33413%
1782
February1st to 10thDay
18%16%8%15%13%4433410%
1620
11th to 20thDay
18%16%5%13%14%5%433415%
1573
21st to endDay
11%15%7%11%10%44346%24%
1408
March1st to 10thDay
14%18%8%12%9%4433421%
1938
11th to 20thDay
15%12%7%10%8%35%345%28%
1980
21st to endDay
18%14%5%8%6%3333432%
2178
April1st to 10thDay
23%14%46%5%24445%27%
2090
11th to 20thDay
21%11%35%424347%38%
2284
21st to endDay
21%13%36%5%24446%32%
2340
May1st to 10thDay
22%10%46%6%35%5%5%5%30%
2340
11th to 20thDay
20%8%25%6%34446%39%
2437
21st to endDay
20%8%36%5%3446%7%35%
2724
June1st to 10thDay
25%8%35%6%34447%31%
2613
11th to 20thDay
21%6%35%4345%5%7%36%
2700
21st to endDay
21%8%47%6%35%446%32%
2700
July1st to 10thDay
16%6%25%6%3446%8%40%
2700
11th to 20thDay
16%7%25%6%35%5%6%8%38%
2626
21st to endDay
18%6%35%6%36%6%5%7%36%
2554
August1st to 10thDay
15%6%25%5%45%6%6%7%41%
2327
11th to 20thDay
16%6%36%5%35%5%6%6%40%
2304
21st to endDay
14%6%245%24446%49%
2537
September1st to 10thDay
18%5%34323437%48%
2160
11th to 20thDay
15%7%24434437%46%
1998
21st to endDay
19%6%35%422346%45%
1980
October1st to 10thDay
19%8%245%2435%7%40%
1800
11th to 20thDay
20%10%36%5%23447%34%
1800
21st to endDay
23%12%36%6%35%345%30%
1942
November1st to 10thDay
21%14%37%6%34346%28%
1591
11th to 20thDay
18%17%8%9%6%44346%21%
1520
21st to endDay
19%19%8%11%6%45%235%17%
1520
December1st to 10thDay
23%21%8%12%6%3234413%
1520
11th to 20thDay
24%18%7%15%9%4433310%
1906
21st to endDay
23%18%11%13%9%3332411%
2431
January1st to 10thNight
19%23%9%13%10%3333311%
2838
11th to 20thNight
20%20%7%14%9%5%3345%10%
2506
21st to endNight
14%15%9%18%13%4434411%
2574
February1st to 10thNight
18%17%9%16%10%4443311%
2340
11th to 20thNight
19%17%7%13%11%5%5%33413%
2273
21st to endNight
12%15%8%12%9%44445%21%
1848
March1st to 10thNight
16%18%6%10%8%4444423%
2008
11th to 20thNight
18%13%6%11%7%45%445%23%
1979
21st to endNight
20%13%7%8%6%34345%29%
2178
April1st to 10thNight
24%14%46%5%34446%26%
1868
11th to 20thNight
22%12%46%43445%8%30%
1625
21st to endNight
22%12%45%6%34446%30%
1620
May1st to 10thNight
21%11%36%5%345%5%7%31%
1620
11th to 20thNight
23%9%35%5%34448%32%
1456
21st to endNight
19%7%46%6%35%45%7%33%
1550
June1st to 10thNight
26%7%35%5%245%7%8%28%
1361
11th to 20thNight
21%7%35%5%345%7%8%33%
1260
21st to endNight
19%7%39%7%46%5%6%8%27%
1260
July1st to 10thNight
18%6%46%5%35%6%6%9%33%
1260
11th to 20thNight
16%8%47%6%36%7%7%7%29%
1314
21st to endNight
16%8%46%5%36%5%6%8%31%
1760
August1st to 10thNight
16%7%25%6%235%7%8%39%
1612
11th to 20thNight
17%9%46%6%3445%8%34%
1596
21st to endNight
14%7%35%4345%48%42%
1818
September1st to 10thNight
15%5%26%435%5%6%7%43%
1800
11th to 20thNight
17%7%25%43345%7%42%
1960
21st to endNight
17%7%35%5%35%5%5%7%40%
1980
October1st to 10thNight
19%6%36%5%3446%6%39%
2159
11th to 20thNight
17%9%35%6%3446%7%35%
2160
21st to endNight
26%14%46%5%24345%28%
2412
November1st to 10thNight
22%12%46%6%3445%6%29%
2487
11th to 20thNight
19%19%6%9%5%35%445%20%
2660
21st to endNight
19%19%7%9%7%34345%20%
2660
December1st to 10thNight
25%20%9%12%6%34345%11%
2660
11th to 20thNight
21%18%8%15%9%3433312%
3293
21st to endNight
25%20%8%12%6%2332317%
5218

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
81%29%6%3
1328
11th to 20thDay
80%47%8%1
1553
21st to endDay
77%37%9%3
1782
February1st to 10thDay
79%48%5%3
1620
11th to 20thDay
76%48%9%3
1581
21st to endDay
62%5%11%15%6%1
1408
March1st to 10thDay
69%37%14%6%1
1942
11th to 20thDay
60%39%15%10%1
1980
21st to endDay
58%37%20%10%2
2178
April1st to 10thDay
60%38%15%12%1
2090
11th to 20thDay
49%39%24%13%2
2284
21st to endDay
54%210%19%11%2
2340
May1st to 10thDay
56%49%19%10%2
2340
11th to 20thDay
49%48%24%14%1
2441
21st to endDay
49%414%21%10%1
2724
June1st to 10thDay
54%410%22%10%
2613
11th to 20thDay
47%413%21%13%2
2700
21st to endDay
54%5%12%18%11%1
2700
July1st to 10thDay
41%417%23%13%1
2625
11th to 20thDay
44%5%15%26%10%1
2545
21st to endDay
47%5%15%23%9%1
2411
August1st to 10thDay
44%5%14%25%13%
2314
11th to 20thDay
45%416%23%11%
2304
21st to endDay
37%315%28%15%1
2537
September1st to 10thDay
39%312%28%15%2
2160
11th to 20thDay
40%312%26%17%2
1998
21st to endDay
43%39%27%16%2
1980
October1st to 10thDay
45%411%27%13%1
1800
11th to 20thDay
51%5%12%24%8%
1800
21st to endDay
58%39%18%11%1
1942
November1st to 10thDay
59%410%19%8%1
1591
11th to 20thDay
66%410%15%5%1
1520
21st to endDay
72%410%11%2
1520
December1st to 10thDay
77%48%9%2
1520
11th to 20thDay
80%46%7%3
1905
21st to endDay
81%211%42
2431
January1st to 10thNight
80%37%8%2
2838
11th to 20thNight
78%49%7%2
2506
21st to endNight
77%48%10%2
2574
February1st to 10thNight
80%46%7%4
2340
11th to 20thNight
78%37%9%4
2276
21st to endNight
66%5%10%13%6%1
1848
March1st to 10thNight
65%5%8%15%7%1
2017
11th to 20thNight
64%410%12%9%1
1980
21st to endNight
59%48%18%10%2
2178
April1st to 10thNight
61%39%13%11%3
1868
11th to 20thNight
53%49%20%12%1
1625
21st to endNight
57%410%18%11%1
1620
May1st to 10thNight
54%311%21%10%1
1620
11th to 20thNight
51%5%7%25%11%1
1457
21st to endNight
50%6%14%20%9%1
1551
June1st to 10thNight
53%6%13%21%7%1
1361
11th to 20thNight
47%5%13%23%10%1
1260
21st to endNight
53%8%12%15%9%3
1260
July1st to 10thNight
45%7%17%21%9%
1225
11th to 20thNight
50%7%15%19%9%1
1272
21st to endNight
50%6%14%21%9%1
1663
August1st to 10thNight
43%414%29%10%
1600
11th to 20thNight
48%5%17%22%8%
1596
21st to endNight
41%5%15%27%12%
1818
September1st to 10thNight
39%6%12%29%13%1
1800
11th to 20thNight
42%311%27%16%1
1960
21st to endNight
44%49%25%16%2
1980
October1st to 10thNight
46%411%25%13%1
2159
11th to 20thNight
48%414%25%8%
2160
21st to endNight
61%39%17%9%1
2412
November1st to 10thNight
56%6%12%18%9%
2487
11th to 20thNight
66%6%9%13%6%
2660
21st to endNight
67%5%14%11%3
2660
December1st to 10thNight
77%39%9%2
2660
11th to 20thNight
78%46%10%2
3295
21st to endNight
75%39%11%2
5218

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
45%25%22%8%
180
11th to 20thDay
42%25%24%7%2
279
21st to endDay
27%29%33%9%2
374
February1st to 10thDay
35%28%28%8%1
340
11th to 20thDay
41%27%22%8%2
336
21st to endDay
32%28%27%12%1
314
March1st to 10thDay
35%25%31%7%2
420
11th to 20thDay
35%28%25%9%3
420
21st to endDay
35%27%24%10%31
462
April1st to 10thDay
45%23%22%8%21
420
11th to 20thDay
35%25%26%12%3
412
21st to endDay
36%18%28%13%5%
420
May1st to 10thDay
34%22%30%10%4
423
11th to 20thDay
28%20%30%16%5%
583
21st to endDay
31%17%30%18%31
680
June1st to 10thDay
36%15%25%19%5%
630
11th to 20thDay
25%17%33%18%6%1
630
21st to endDay
30%12%34%17%5%1
630
July1st to 10thDay
22%12%37%20%7%1
620
11th to 20thDay
22%8%38%22%9%1
618
21st to endDay
21%10%41%23%4
494
August1st to 10thDay
16%12%43%24%41
446
11th to 20thDay
22%11%34%21%9%2
439
21st to endDay
18%14%30%27%8%2
495
September1st to 10thDay
19%12%40%21%6%1
450
11th to 20thDay
25%17%31%19%6%3
450
21st to endDay
25%18%30%18%8%2
450
October1st to 10thDay
29%16%24%19%9%3
360
11th to 20thDay
30%18%28%16%5%2
360
21st to endDay
36%21%25%13%41
396
November1st to 10thDay
33%21%29%12%41
365
11th to 20thDay
41%22%22%12%4
370
21st to endDay
39%25%25%6%31
370
December1st to 10thDay
40%26%23%10%1
370
11th to 20thDay
49%26%19%6%1
370
21st to endDay
42%27%24%5%11
198
January1st to 10thNight
38%25%23%13%1
850
11th to 20thNight
38%24%23%11%3
754
21st to endNight
31%27%28%12%3
792
February1st to 10thNight
36%25%27%11%2
720
11th to 20thNight
39%24%25%10%2
703
21st to endNight
27%28%27%16%3
592
March1st to 10thNight
32%25%28%13%1
720
11th to 20thNight
32%21%26%18%3
720
21st to endNight
31%20%27%17%4
792
April1st to 10thNight
40%18%26%15%2
608
11th to 20thNight
30%21%30%16%3
534
21st to endNight
34%16%26%18%6%
540
May1st to 10thNight
29%15%32%19%5%1
540
11th to 20thNight
30%14%29%23%4
532
21st to endNight
22%15%38%20%5%1
583
June1st to 10thNight
30%12%31%22%5%
461
11th to 20thNight
25%12%31%26%6%1
360
21st to endNight
23%8%40%19%9%1
360
July1st to 10thNight
18%9%40%26%7%
350
11th to 20thNight
23%7%34%24%12%
402
21st to endNight
20%8%34%33%5%
590
August1st to 10thNight
18%8%35%30%8%1
538
11th to 20thNight
21%9%30%30%9%1
532
21st to endNight
19%8%33%29%10%1
594
September1st to 10thNight
18%10%35%27%10%1
540
11th to 20thNight
23%10%27%26%12%1
700
21st to endNight
23%13%31%21%10%1
720
October1st to 10thNight
23%10%27%28%10%1
720
11th to 20thNight
23%20%29%19%8%1
720
21st to endNight
38%20%22%16%4
792
November1st to 10thNight
33%17%25%18%5%1
778
11th to 20thNight
35%22%21%16%6%
850
21st to endNight
36%21%24%15%3
850
December1st to 10thNight
41%22%24%11%2
850
11th to 20thNight
39%27%23%9%2
850
21st to endNight
41%24%21%11%2
935
Page generated at 2024-01-12 17:17:48. Version ac07

Copyright 2024 Attilla Danko


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