The Islands Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Islands Provincial Park clear sky chart from 2005-11-05 to 2018-04-23.

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
24%
16028
14%
49252
6%
15986
32%
15986
16%
35176

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
14%
808
11%
2644
3%
804
24%
804
11%
1959
January16th to endNight
14%
832
11%
2704
2%
832
23%
832
11%
2026
February1st to 15thNight
13%
761
9%
2481
1%
761
22%
761
9%
1904
February16th to endNight
17%
683
13%
2158
4%
683
29%
683
13%
1548
March1st to 15thNight
16%
780
14%
2161
4%
780
26%
780
14%
1637
March16th to endNight
20%
832
17%
2288
5%
832
31%
832
19%
1618
April1st to 15thNight
18%
634
15%
1970
6%
634
28%
634
16%
1416
April16th to endNight
24%
557
15%
1671
6%
557
31%
557
19%
1174
May1st to 15thNight
20%
540
12%
1608
4%
540
27%
540
15%
1200
May16th to endNight
26%
561
11%
1496
6%
560
31%
560
19%
1124
June1st to 15thNight
22%
512
9%
1412
4%
512
26%
512
15%
1089
June16th to endNight
31%
360
9%
1260
5%
360
36%
360
15%
907
July1st to 15thNight
36%
387
11%
1237
8%
387
41%
387
18%
858
July16th to endNight
31%
565
9%
1561
7%
532
34%
532
18%
1167
August1st to 15thNight
41%
539
13%
1608
10%
535
43%
535
23%
1093
August16th to endNight
40%
573
19%
1758
12%
573
46%
573
25%
1144
September1st to 15thNight
35%
585
19%
1845
12%
585
43%
585
24%
1185
September16th to endNight
39%
717
24%
1980
15%
717
46%
717
28%
1283
October1st to 15thNight
31%
720
19%
2160
8%
720
41%
720
23%
1428
October16th to endNight
26%
768
19%
2304
8%
768
35%
768
20%
1526
November1st to 15thNight
31%
784
16%
2574
9%
784
40%
784
19%
1720
November16th to endNight
22%
825
13%
2730
5%
825
33%
825
14%
1925
December1st to 15thNight
17%
825
11%
2730
3%
825
27%
825
11%
2040
December16th to endNight
12%
880
12%
2912
2%
880
24%
880
9%
2205

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
22%9%36%5%34446%30%
50253
Night
21%9%36%5%3445%6%28%
49430
TransparencyDay
53%311%20%10%1
49949
Night
54%311%20%9%
49252
SeeingDay
27%14%30%18%7%1
8063
Night
26%13%29%22%7%
16031

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
19%14%5%7%7%35%5%6%6%16%
1622
16th to endDay
20%11%48%7%46%45%7%19%
1872
February1st to 15thDay
18%14%6%8%8%5%7%45%5%15%
1710
16th to endDay
16%13%5%9%6%35%45%7%23%
1597
March1st to 15thDay
22%14%36%5%23435%26%
2118
16th to endDay
18%11%47%6%24245%31%
2288
April1st to 15thDay
21%12%35%5%24445%28%
2305
16th to endDay
25%8%25%423336%34%
2404
May1st to 15thDay
27%9%36%423336%28%
2344
16th to endDay
26%7%35%32335%7%30%
2618
June1st to 15thDay
28%9%35%424345%28%
2556
16th to endDay
23%6%25%5%2445%7%32%
2700
July1st to 15thDay
23%7%2432345%8%33%
2634
16th to endDay
22%9%35%5%35%5%5%6%29%
2497
August1st to 15thDay
20%6%25%5%25%45%6%35%
2340
16th to endDay
17%6%1442345%7%42%
2444
September1st to 15thDay
18%5%2432335%6%44%
2112
16th to endDay
20%6%24433336%42%
1979
October1st to 15thDay
21%7%24433426%40%
1800
16th to endDay
22%6%37%5%35%346%31%
1917
November1st to 15thDay
21%11%35%6%2435%5%29%
1612
16th to endDay
21%11%48%6%45%436%23%
1560
December1st to 15thDay
26%11%48%5%35%45%6%19%
1560
16th to endDay
23%12%5%8%6%35%5%45%19%
1664
January1st to 15thNight
17%10%5%8%7%35%6%6%7%20%
2644
16th to endNight
18%12%48%6%36%5%6%8%19%
2704
February1st to 15thNight
19%11%5%9%8%45%5%5%5%18%
2480
16th to endNight
15%10%47%6%46%5%5%8%24%
2158
March1st to 15thNight
21%11%35%6%46%5%4425%
2149
16th to endNight
17%9%46%6%24446%32%
2288
April1st to 15thNight
24%10%26%5%23346%30%
1970
16th to endNight
24%8%244245%37%31%
1671
May1st to 15thNight
27%10%37%42345%6%25%
1608
16th to endNight
26%8%25%5%2445%5%29%
1494
June1st to 15thNight
28%9%47%433346%24%
1412
16th to endNight
25%8%35%5%2435%5%30%
1260
July1st to 15thNight
22%9%3442346%9%29%
1311
16th to endNight
24%9%36%5%35%45%7%25%
1668
August1st to 15thNight
19%8%36%424247%36%
1620
16th to endNight
17%7%2442435%8%39%
1758
September1st to 15thNight
19%7%24424345%41%
1845
16th to endNight
19%6%2431335%6%42%
1980
October1st to 15thNight
21%6%34423446%38%
2160
16th to endNight
20%7%25%324445%37%
2304
November1st to 15thNight
19%7%35%5%35%45%7%32%
2574
16th to endNight
21%9%36%5%35%5%5%6%28%
2730
December1st to 15thNight
23%10%47%6%3445%7%21%
2730
16th to endNight
24%10%47%6%45%45%6%20%
2912

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
62%412%14%5%
1623
16th to endDay
60%49%19%6%
1872
February1st to 15thDay
64%411%13%5%
1713
16th to endDay
57%311%20%6%
1597
March1st to 15thDay
58%29%18%9%1
2129
16th to endDay
53%28%19%12%2
2288
April1st to 15thDay
56%38%16%13%1
2305
16th to endDay
50%210%21%12%1
2404
May1st to 15thDay
58%38%18%9%1
2344
16th to endDay
52%313%20%7%
2622
June1st to 15thDay
59%39%17%8%1
2556
16th to endDay
50%412%19%11%1
2700
July1st to 15thDay
48%314%22%10%1
2480
16th to endDay
54%412%20%7%
2341
August1st to 15thDay
47%312%22%12%1
2327
16th to endDay
40%313%27%15%
2444
September1st to 15thDay
40%311%24%18%1
2112
16th to endDay
42%37%27%17%1
1979
October1st to 15thDay
45%310%25%14%1
1800
16th to endDay
52%311%22%9%
1917
November1st to 15thDay
54%312%20%8%1
1612
16th to endDay
58%412%18%5%
1560
December1st to 15thDay
63%311%15%5%
1560
16th to endDay
62%48%17%7%
1664
January1st to 15thNight
58%314%16%5%
2644
16th to endNight
59%412%18%5%
2704
February1st to 15thNight
63%311%17%5%
2481
16th to endNight
55%313%19%7%
2158
March1st to 15thNight
58%39%17%9%1
2161
16th to endNight
51%210%20%14%1
2288
April1st to 15thNight
55%28%18%11%3
1970
16th to endNight
52%310%20%10%2
1671
May1st to 15thNight
59%27%20%9%
1608
16th to endNight
56%312%18%7%1
1496
June1st to 15thNight
61%28%20%6%
1412
16th to endNight
56%410%16%11%
1260
July1st to 15thNight
51%413%22%8%
1237
16th to endNight
57%311%20%6%1
1561
August1st to 15thNight
49%111%25%10%
1608
16th to endNight
44%311%26%13%
1758
September1st to 15thNight
45%28%26%15%2
1845
16th to endNight
42%25%29%18%
1980
October1st to 15thNight
44%49%25%13%1
2160
16th to endNight
46%211%26%11%
2304
November1st to 15thNight
48%315%22%9%
2574
16th to endNight
52%5%14%19%8%
2730
December1st to 15thNight
59%312%19%4
2730
16th to endNight
61%310%17%6%
2912

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
21%23%32%18%3
285
16th to endDay
24%24%35%11%3
304
February1st to 15thDay
28%21%29%17%3
281
16th to endDay
21%19%38%16%4
265
March1st to 15thDay
29%24%30%10%4
330
16th to endDay
24%22%32%12%5%1
352
April1st to 15thDay
28%23%30%13%2
330
16th to endDay
25%14%35%17%5%1
289
May1st to 15thDay
31%15%31%14%6%1
300
16th to endDay
33%11%28%17%7%1
519
June1st to 15thDay
32%8%31%20%5%
495
16th to endDay
32%8%26%23%8%1
495
July1st to 15thDay
31%5%24%25%11%1
475
16th to endDay
29%5%23%30%10%
358
August1st to 15thDay
22%6%31%24%12%1
313
16th to endDay
22%6%28%24%14%3
332
September1st to 15thDay
20%9%33%27%7%2
315
16th to endDay
22%8%32%18%12%4
313
October1st to 15thDay
23%7%35%17%12%2
270
16th to endDay
23%22%27%18%7%
288
November1st to 15thDay
20%19%29%18%10%1
280
16th to endDay
27%22%24%18%5%1
285
December1st to 15thDay
37%19%25%14%3
285
16th to endDay
31%24%29%10%3
304
January1st to 15thNight
22%21%33%18%4
808
16th to endNight
25%20%30%18%3
832
February1st to 15thNight
26%21%31%18%1
764
16th to endNight
21%18%35%17%5%
683
March1st to 15thNight
27%17%32%17%4
780
16th to endNight
21%19%33%18%6%
832
April1st to 15thNight
28%11%34%20%4
634
16th to endNight
29%8%32%19%8%1
557
May1st to 15thNight
32%8%30%21%5%
540
16th to endNight
29%6%30%24%7%2
561
June1st to 15thNight
29%7%31%25%5%
512
16th to endNight
30%226%28%10%
360
July1st to 15thNight
27%125%34%11%
387
16th to endNight
28%326%31%9%
565
August1st to 15thNight
21%423%35%13%1
539
16th to endNight
21%325%30%16%1
573
September1st to 15thNight
22%5%30%28%10%2
585
16th to endNight
22%6%24%26%16%2
717
October1st to 15thNight
25%8%28%24%10%1
720
16th to endNight
24%17%27%21%7%
768
November1st to 15thNight
23%12%26%25%10%1
784
16th to endNight
25%18%28%19%8%
825
December1st to 15thNight
29%19%27%18%4
825
16th to endNight
31%21%29%15%2
880
Page generated at 2018-04-24 11:03:07. Version ac04

Copyright 2018 A. Danko


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