Daniel's Harbour
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Daniel's Harbour clear sky chart from 2005-11-05 to 2019-06-02.

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
17%
17452
5%
53756
2%
17408
19%
17408
7%
45783

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
7%
897
2%
3012
1%
896
8%
896
1%
2842
January16th to endNight
8%
960
3%
3136
1%
960
9%
960
2%
2951
February1st to 15thNight
8%
870
2%
2843
1%
869
9%
869
2%
2665
February16th to endNight
16%
735
3%
2238
1%
735
18%
735
5%
1959
March1st to 15thNight
15%
840
8%
2509
3%
836
19%
836
7%
2136
March16th to endNight
14%
714
7%
2346
3%
714
19%
714
6%
1947
April1st to 15thNight
19%
629
8%
2093
6%
629
23%
629
6%
1742
April16th to endNight
20%
623
10%
1822
4%
623
26%
623
11%
1401
May1st to 15thNight
29%
630
9%
1680
3%
630
32%
630
15%
1264
May16th to endNight
22%
657
5%
1607
2%
656
24%
656
13%
1304
June1st to 15thNight
25%
589
2%
1374
1%
589
26%
589
13%
1130
June16th to endNight
25%
505
1%
1285
1%
505
26%
505
14%
998
July1st to 15thNight
23%
555
3%
1315
2%
555
25%
555
17%
1027
July16th to endNight
28%
613
4%
1547
2%
580
31%
580
14%
1213
August1st to 15thNight
32%
574
6%
1522
2%
570
34%
570
16%
1168
August16th to endNight
30%
621
8%
1903
5%
621
34%
621
14%
1435
September1st to 15thNight
24%
585
8%
1956
5%
585
30%
585
11%
1480
September16th to endNight
17%
583
8%
2145
5%
583
22%
583
8%
1647
October1st to 15thNight
18%
736
8%
2323
4%
736
21%
736
9%
1886
October16th to endNight
16%
896
6%
2704
3%
896
18%
896
6%
2337
November1st to 15thNight
11%
880
5%
2741
1%
880
13%
880
5%
2402
November16th to endNight
9%
900
4%
3145
2%
900
11%
900
3%
2805
December1st to 15thNight
7%
900
2%
3150
0%
900
9%
900
2%
2909
December16th to endNight
8%
960
2%
3360
1%
960
9%
960
2%
3135

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
24%13%48%6%34445%21%
54544
Night
24%16%6%9%8%3333416%
53930
TransparencyDay
66%5%10%13%4
54224
Night
73%48%10%3
53768
SeeingDay
30%20%22%17%7%2
10348
Night
29%24%19%17%7%1
17457

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%21%10%17%10%5%42225%
1585
16th to endDay
15%21%8%13%19%6%42124
1792
February1st to 15thDay
13%17%7%12%15%7%7%3436%
1675
16th to endDay
13%22%6%9%8%5%433416%
1806
March1st to 15thDay
17%17%7%10%7%35%34418%
2090
16th to endDay
17%16%6%8%8%44435%20%
2579
April1st to 15thDay
19%18%5%8%6%24445%19%
2516
16th to endDay
22%11%46%43345%6%27%
2742
May1st to 15thDay
23%9%35%5%2445%6%30%
2932
16th to endDay
30%9%36%423445%25%
3211
June1st to 15thDay
25%9%37%5%3446%7%22%
2940
16th to endDay
28%8%26%5%2445%5%26%
2969
July1st to 15thDay
24%8%25%4345%5%7%28%
2902
16th to endDay
28%6%25%6%4446%7%23%
2877
August1st to 15thDay
21%7%35%6%2445%7%31%
2680
16th to endDay
27%8%24423447%30%
2647
September1st to 15thDay
29%6%34423446%29%
2334
16th to endDay
30%10%25%31345%6%25%
2145
October1st to 15thDay
30%10%36%423335%27%
1966
16th to endDay
35%17%35%42223417%
1872
November1st to 15thDay
30%20%6%6%42243414%
1773
16th to endDay
25%23%8%13%41223212%
1473
December1st to 15thDay
20%21%9%18%11%232224
1470
16th to endDay
20%20%10%14%14%5%21126%
1568
January1st to 15thNight
18%23%9%15%11%6%33224
3012
16th to endNight
16%18%8%14%15%6%6%2135%
3136
February1st to 15thNight
15%16%6%14%16%8%5%3236%
2843
16th to endNight
13%16%8%13%11%34435%14%
2238
March1st to 15thNight
15%16%6%11%9%45%336%17%
2507
16th to endNight
17%20%7%10%7%3443417%
2346
April1st to 15thNight
24%18%6%8%6%2333418%
2093
16th to endNight
19%13%5%7%5%24346%25%
1822
May1st to 15thNight
24%10%25%5%24445%30%
1680
16th to endNight
32%9%36%5%23435%22%
1605
June1st to 15thNight
26%10%47%6%35%45%422%
1374
16th to endNight
28%6%36%5%3445%6%25%
1285
July1st to 15thNight
28%8%25%5%23446%27%
1386
16th to endNight
31%8%35%5%2445%5%23%
1643
August1st to 15thNight
22%8%36%5%35%446%28%
1533
16th to endNight
27%8%3442445%7%26%
1903
September1st to 15thNight
31%7%25%5%2345%5%26%
1956
16th to endNight
32%8%26%423345%24%
2145
October1st to 15thNight
30%13%35%433335%22%
2323
16th to endNight
34%19%45%5%23235%14%
2704
November1st to 15thNight
30%22%5%6%5%2233412%
2741
16th to endNight
27%24%9%9%41232310%
3145
December1st to 15thNight
21%23%10%15%8%222226%
3150
16th to endNight
20%21%11%14%12%412125%
3360

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
89%1431
1586
16th to endDay
90%123
1792
February1st to 15thDay
84%35%6%
1678
16th to endDay
76%5%48%5%
1806
March1st to 15thDay
71%48%10%4
2100
16th to endDay
70%6%5%9%7%
2579
April1st to 15thDay
68%6%7%12%4
2516
16th to endDay
57%6%10%16%8%
2742
May1st to 15thDay
55%6%9%19%7%
2932
16th to endDay
62%5%12%14%5%
3215
June1st to 15thDay
60%7%13%15%3
2940
16th to endDay
59%5%15%14%4
2969
July1st to 15thDay
53%5%17%18%4
2745
16th to endDay
57%5%16%17%2
2710
August1st to 15thDay
51%6%19%17%3
2666
16th to endDay
55%6%16%17%4
2647
September1st to 15thDay
56%6%13%17%5%
2334
16th to endDay
59%6%13%15%4
2145
October1st to 15thDay
63%410%15%5%
1966
16th to endDay
75%47%8%3
1872
November1st to 15thDay
77%47%8%1
1773
16th to endDay
80%36%7%1
1473
December1st to 15thDay
88%15%3
1470
16th to endDay
88%234
1568
January1st to 15thNight
89%242
3012
16th to endNight
88%2331
3136
February1st to 15thNight
87%344
2844
16th to endNight
76%45%9%3
2238
March1st to 15thNight
70%6%7%11%4
2520
16th to endNight
72%37%11%4
2346
April1st to 15thNight
71%46%12%5%
2093
16th to endNight
59%5%11%14%8%
1822
May1st to 15thNight
55%5%12%18%7%1
1680
16th to endNight
63%410%16%4
1607
June1st to 15thNight
63%5%9%17%2
1374
16th to endNight
58%5%17%14%5%
1285
July1st to 15thNight
56%5%15%17%5%
1315
16th to endNight
60%5%14%16%2
1547
August1st to 15thNight
56%6%17%16%3
1522
16th to endNight
57%5%15%15%4
1903
September1st to 15thNight
60%5%12%19%2
1956
16th to endNight
63%413%14%3
2145
October1st to 15thNight
67%410%12%4
2323
16th to endNight
75%47%9%2
2704
November1st to 15thNight
77%47%8%1
2741
16th to endNight
82%26%6%1
3145
December1st to 15thNight
86%2441
3150
16th to endNight
88%2441
3360

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
23%32%25%13%3
330
16th to endDay
25%30%22%13%5%1
352
February1st to 15thDay
22%32%28%11%5%
326
16th to endDay
28%27%21%13%6%2
290
March1st to 15thDay
22%24%27%15%6%2
330
16th to endDay
27%21%27%16%6%1
397
April1st to 15thDay
32%25%24%11%41
393
16th to endDay
28%20%22%16%8%2
587
May1st to 15thDay
26%19%20%19%10%2
618
16th to endDay
32%17%21%18%7%1
679
June1st to 15thDay
31%17%17%18%11%3
575
16th to endDay
31%18%24%15%6%3
570
July1st to 15thDay
29%15%22%21%7%3
550
16th to endDay
30%14%17%24%9%2
594
August1st to 15thDay
25%12%23%21%12%4
550
16th to endDay
32%10%19%21%13%1
532
September1st to 15thDay
34%17%23%18%6%
373
16th to endDay
38%17%26%13%4
314
October1st to 15thDay
33%22%23%11%5%3
315
16th to endDay
44%17%16%13%5%1
336
November1st to 15thDay
38%21%22%13%22
325
16th to endDay
35%24%18%15%5%1
330
December1st to 15thDay
26%29%23%16%3
330
16th to endDay
26%28%24%13%5%1
352
January1st to 15thNight
27%34%21%11%4
900
16th to endNight
19%36%22%14%5%
960
February1st to 15thNight
23%33%24%12%6%
872
16th to endNight
20%29%20%19%6%3
735
March1st to 15thNight
18%29%25%17%6%1
840
16th to endNight
24%26%26%14%6%
714
April1st to 15thNight
32%26%14%19%6%1
629
16th to endNight
26%22%22%18%7%2
623
May1st to 15thNight
26%21%16%21%13%1
630
16th to endNight
32%19%17%21%7%
657
June1st to 15thNight
30%19%13%22%11%1
589
16th to endNight
28%19%17%23%7%2
505
July1st to 15thNight
30%17%23%16%10%2
555
16th to endNight
29%19%14%24%11%1
613
August1st to 15thNight
25%14%19%21%17%1
574
16th to endNight
31%13%18%21%13%2
621
September1st to 15thNight
34%16%20%19%8%
585
16th to endNight
37%19%20%18%2
583
October1st to 15thNight
39%19%18%15%5%1
736
16th to endNight
43%17%16%16%5%
896
November1st to 15thNight
42%24%16%11%4
880
16th to endNight
37%26%19%13%31
900
December1st to 15thNight
28%30%21%15%4
900
16th to endNight
28%29%19%15%6%1
960
Page generated at 2019-06-02 20:43:11. Version ac04

Copyright 2019 A. Danko


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