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 2005-11-06 to 2024-01-11.

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
23%
23645
14%
74267
6%
23589
32%
23589
16%
52945

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
13%
846
10%
2640
3%
843
21%
843
10%
2028
January11th to 20thNight
17%
724
11%
2351
3%
724
25%
724
10%
1789
January21st to endNight
15%
792
13%
2574
3%
792
26%
792
12%
1887
February1st to 10thNight
13%
720
9%
2340
1%
720
22%
720
9%
1782
February11th to 20thNight
12%
700
12%
2276
2%
700
24%
700
9%
1692
February21st to endNight
18%
592
15%
1839
5%
592
31%
592
15%
1288
March1st to 10thNight
15%
720
15%
2001
4%
720
25%
720
14%
1480
March11th to 20thNight
19%
720
15%
1980
4%
720
30%
720
16%
1458
March21st to endNight
19%
792
20%
2178
5%
792
33%
792
20%
1520
April1st to 10thNight
15%
610
14%
1870
5%
610
25%
610
14%
1363
April11th to 20thNight
16%
534
18%
1652
4%
534
29%
534
18%
1130
April21st to endNight
24%
540
15%
1620
7%
540
31%
540
18%
1150
May1st to 10thNight
19%
540
13%
1620
5%
540
26%
540
16%
1181
May11th to 20thNight
22%
532
18%
1489
8%
532
31%
532
19%
1063
May21st to endNight
26%
583
11%
1551
6%
582
31%
582
19%
1152
June1st to 10thNight
24%
540
13%
1440
6%
540
31%
540
19%
1064
June11th to 20thNight
26%
409
12%
1309
7%
409
34%
409
18%
904
June21st to endNight
28%
360
8%
1260
5%
360
33%
360
13%
932
July1st to 10thNight
33%
350
13%
1225
8%
350
43%
350
18%
830
July11th to 20thNight
32%
509
10%
1415
7%
509
36%
509
17%
1067
July21st to endNight
31%
590
11%
1672
9%
558
34%
558
19%
1217
August1st to 10thNight
36%
538
13%
1600
8%
534
39%
534
23%
1083
August11th to 20thNight
36%
532
15%
1596
9%
532
40%
532
20%
1129
August21st to endNight
39%
594
18%
1840
11%
594
46%
594
23%
1211
September1st to 10thNight
38%
540
20%
1800
13%
540
47%
540
24%
1124
September11th to 20thNight
36%
697
22%
1957
13%
697
45%
697
27%
1270
September21st to endNight
34%
720
22%
1980
11%
720
43%
720
24%
1347
October1st to 10thNight
32%
720
19%
2160
9%
720
42%
720
23%
1422
October11th to 20thNight
31%
720
22%
2160
9%
720
42%
720
23%
1393
October21st to endNight
25%
792
18%
2376
8%
792
33%
792
18%
1630
November1st to 10thNight
29%
767
18%
2462
9%
767
39%
767
20%
1619
November11th to 20thNight
21%
850
16%
2660
7%
850
32%
850
15%
1876
November21st to endNight
20%
850
11%
2660
3%
850
30%
850
13%
1909
December1st to 10thNight
17%
850
11%
2660
3%
850
26%
850
11%
2042
December11th to 20thNight
12%
850
11%
3238
2%
849
23%
849
8%
2507
December21st to endNight
15%
922
9%
4816
2%
907
27%
907
6%
3406

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%10%36%5%3445%6%31%
75121
Night
22%10%46%5%3445%7%30%
74567
TransparencyDay
53%311%20%11%1
74831
Night
54%311%21%10%1
74392
SeeingDay
28%16%32%18%6%1
15958
Night
27%14%30%22%7%1
23661

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
20%17%6%9%7%345%5%7%17%
1523
11th to 20thDay
25%12%5%8%7%46%46%5%18%
1621
21st to endDay
16%10%5%10%8%5%6%5%5%8%21%
1782
February1st to 10thDay
20%15%6%9%7%46%5%45%18%
1620
11th to 20thDay
19%11%5%10%9%45%45%6%21%
1573
21st to endDay
15%14%6%8%6%25%46%8%27%
1412
March1st to 10thDay
19%14%49%6%345%45%26%
1954
11th to 20thDay
19%11%5%6%7%34346%32%
1980
21st to endDay
19%12%47%6%34345%32%
2178
April1st to 10thDay
25%14%46%5%34345%27%
2088
11th to 20thDay
22%9%35%5%35%446%35%
2253
21st to endDay
26%9%36%42445%6%33%
2340
May1st to 10thDay
27%11%36%6%34445%28%
2340
11th to 20thDay
24%8%35%42345%6%35%
2405
21st to endDay
24%8%35%43445%7%32%
2724
June1st to 10thDay
27%8%35%424446%32%
2520
11th to 20thDay
22%8%35%5%2435%6%37%
2664
21st to endDay
26%7%35%5%35%45%8%29%
2700
July1st to 10thDay
22%6%36%4245%6%7%36%
2692
11th to 20thDay
21%8%35%5%35%6%5%9%31%
2480
21st to endDay
22%9%35%435%46%7%32%
2548
August1st to 10thDay
18%7%25%5%35%46%7%38%
2327
11th to 20thDay
19%7%36%5%3446%8%36%
2304
21st to endDay
19%6%15%42445%7%42%
2516
September1st to 10thDay
16%7%25%42445%7%44%
2160
11th to 20thDay
19%6%35%43335%5%43%
1998
21st to endDay
21%8%24433336%42%
1979
October1st to 10thDay
20%7%245%34447%39%
1800
11th to 20thDay
21%7%26%4445%47%35%
1800
21st to endDay
22%8%37%6%45%35%6%31%
1977
November1st to 10thDay
21%9%35%5%25%45%6%34%
1614
11th to 20thDay
21%12%47%6%34448%27%
1520
21st to endDay
20%13%48%7%45%5%5%5%24%
1520
December1st to 10thDay
25%13%48%6%4445%6%21%
1520
11th to 20thDay
31%12%48%5%35%445%19%
1906
21st to endDay
23%13%7%7%5%35%45%5%24%
2783
January1st to 10thNight
20%13%5%10%7%45%5%6%6%19%
2640
11th to 20thNight
21%12%48%7%35%6%6%7%20%
2351
21st to endNight
16%11%6%10%8%36%6%6%8%20%
2574
February1st to 10thNight
19%11%6%9%8%46%5%5%5%21%
2340
11th to 20thNight
19%11%48%8%5%6%5%6%7%21%
2273
21st to endNight
13%11%5%8%7%46%6%5%8%29%
1839
March1st to 10thNight
19%11%46%6%5%7%5%46%28%
1992
11th to 20thNight
19%10%46%8%35%6%5%6%29%
1979
21st to endNight
18%9%47%5%3435%6%36%
2178
April1st to 10thNight
24%12%36%5%2345%6%29%
1870
11th to 20thNight
24%10%34434447%34%
1652
21st to endNight
26%9%35%5%345%47%32%
1620
May1st to 10thNight
24%10%46%4345%5%6%28%
1620
11th to 20thNight
26%8%36%5%33446%33%
1488
21st to endNight
23%10%27%5%2446%6%31%
1550
June1st to 10thNight
26%8%47%43345%8%29%
1440
11th to 20thNight
22%9%36%5%34446%34%
1309
21st to endNight
28%9%45%5%3435%6%27%
1260
July1st to 10thNight
23%9%35%5%2346%9%31%
1260
11th to 20thNight
22%9%46%6%45%5%6%8%26%
1462
21st to endNight
25%9%35%5%35%5%47%31%
1770
August1st to 10thNight
18%9%35%5%24338%38%
1612
11th to 20thNight
20%10%36%6%2436%7%33%
1596
21st to endNight
19%7%2443445%8%39%
1840
September1st to 10thNight
17%7%35%5%35%45%7%41%
1800
11th to 20thNight
21%7%2432445%6%44%
1957
21st to endNight
21%8%35%32335%6%39%
1980
October1st to 10thNight
21%7%345%34447%39%
2160
11th to 20thNight
20%7%25%43345%6%41%
2160
21st to endNight
24%8%35%424447%34%
2376
November1st to 10thNight
19%7%45%5%3445%6%37%
2462
11th to 20thNight
20%9%36%6%46%5%5%7%28%
2660
21st to endNight
20%12%47%5%35%5%6%6%28%
2660
December1st to 10thNight
24%12%48%7%45%45%7%21%
2660
11th to 20thNight
29%12%46%5%345%5%6%21%
3293
21st to endNight
25%11%5%8%5%35%445%25%
4884

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
64%310%15%7%
1524
11th to 20thDay
64%412%16%4
1621
21st to endDay
58%49%21%7%1
1782
February1st to 10thDay
65%311%13%7%1
1620
11th to 20thDay
61%411%17%7%1
1581
21st to endDay
54%411%21%9%2
1412
March1st to 10thDay
58%28%19%11%2
1958
11th to 20thDay
52%311%19%14%2
1980
21st to endDay
55%37%20%13%3
2178
April1st to 10thDay
59%29%15%13%1
2088
11th to 20thDay
50%410%22%14%1
2253
21st to endDay
52%310%20%13%2
2340
May1st to 10thDay
61%38%18%10%1
2340
11th to 20thDay
50%38%23%14%2
2409
21st to endDay
53%413%19%10%1
2724
June1st to 10thDay
54%38%23%11%1
2520
11th to 20thDay
50%211%20%14%3
2664
21st to endDay
55%413%17%10%1
2700
July1st to 10thDay
48%315%21%11%2
2617
11th to 20thDay
51%313%24%8%1
2404
21st to endDay
51%413%23%8%1
2406
August1st to 10thDay
46%414%23%13%1
2314
11th to 20thDay
47%315%23%11%1
2304
21st to endDay
42%311%26%17%1
2516
September1st to 10thDay
41%312%25%18%2
2160
11th to 20thDay
43%39%25%17%3
1998
21st to endDay
45%37%24%19%2
1979
October1st to 10thDay
45%410%26%13%2
1800
11th to 20thDay
49%312%25%11%1
1800
21st to endDay
55%310%20%12%1
1977
November1st to 10thDay
51%312%22%11%1
1614
11th to 20thDay
55%411%20%9%
1520
21st to endDay
58%412%20%5%1
1520
December1st to 10thDay
64%311%16%6%
1520
11th to 20thDay
67%38%14%7%
1905
21st to endDay
61%214%15%7%1
2783
January1st to 10thNight
63%311%17%6%1
2640
11th to 20thNight
61%5%14%15%6%
2351
21st to endNight
58%413%19%6%
2574
February1st to 10thNight
63%312%15%7%
2340
11th to 20thNight
60%310%18%8%1
2276
21st to endNight
52%312%21%10%1
1839
March1st to 10thNight
56%49%19%11%2
2001
11th to 20thNight
55%311%15%14%2
1980
21st to endNight
49%28%23%15%2
2178
April1st to 10thNight
58%29%15%12%4
1870
11th to 20thNight
50%38%24%13%1
1652
21st to endNight
53%410%20%11%2
1620
May1st to 10thNight
57%38%22%10%1
1620
11th to 20thNight
53%37%24%13%1
1489
21st to endNight
56%312%21%8%1
1551
June1st to 10thNight
56%27%25%9%1
1440
11th to 20thNight
52%311%20%13%1
1309
21st to endNight
60%49%15%11%1
1260
July1st to 10thNight
52%314%22%9%
1225
11th to 20thNight
58%410%20%8%1
1415
21st to endNight
55%311%22%7%2
1672
August1st to 10thNight
50%211%25%12%
1600
11th to 20thNight
52%313%22%9%1
1596
21st to endNight
46%310%26%14%1
1840
September1st to 10thNight
44%38%28%15%3
1800
11th to 20thNight
43%38%27%18%2
1957
21st to endNight
48%26%26%17%1
1980
October1st to 10thNight
45%410%24%15%2
2160
11th to 20thNight
44%311%29%12%1
2160
21st to endNight
51%211%23%13%1
2376
November1st to 10thNight
48%214%24%11%
2462
11th to 20thNight
53%312%21%10%
2660
21st to endNight
53%5%15%19%7%
2660
December1st to 10thNight
63%212%17%6%
2660
11th to 20thNight
63%39%17%6%1
3295
21st to endNight
61%211%20%5%1
4884

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
30%25%28%14%4
370
11th to 20thDay
29%20%33%15%3
341
21st to endDay
19%29%33%16%31
374
February1st to 10thDay
31%23%31%12%2
340
11th to 20thDay
31%26%27%13%3
336
21st to endDay
27%23%31%15%3
316
March1st to 10thDay
30%22%34%11%3
420
11th to 20thDay
28%24%32%11%41
420
21st to endDay
26%23%33%11%6%1
462
April1st to 10thDay
35%23%29%11%2
420
11th to 20thDay
28%21%37%12%2
412
21st to endDay
31%17%32%13%5%1
420
May1st to 10thDay
30%22%31%12%31
423
11th to 20thDay
26%19%32%17%5%1
551
21st to endDay
32%11%32%18%7%1
680
June1st to 10thDay
32%10%33%20%5%
630
11th to 20thDay
26%11%34%21%8%1
630
21st to endDay
32%9%31%22%5%1
630
July1st to 10thDay
28%7%28%26%9%1
620
11th to 20thDay
28%5%33%24%10%1
578
21st to endDay
25%7%33%27%8%1
488
August1st to 10thDay
18%8%38%25%9%2
446
11th to 20thDay
26%8%33%20%11%2
439
21st to endDay
23%8%32%22%11%2
495
September1st to 10thDay
19%10%34%28%8%2
450
11th to 20thDay
25%11%32%19%8%4
450
21st to endDay
22%11%36%20%7%3
449
October1st to 10thDay
23%10%35%20%11%2
360
11th to 20thDay
20%18%32%21%7%2
360
21st to endDay
26%16%33%17%7%1
396
November1st to 10thDay
23%20%31%17%8%1
365
11th to 20thDay
29%24%27%13%6%
370
21st to endDay
30%22%29%16%31
370
December1st to 10thDay
37%17%29%14%3
370
11th to 20thDay
39%24%23%11%3
370
21st to endDay
31%24%28%13%31
407
January1st to 10thNight
29%22%29%17%4
846
11th to 20thNight
29%16%30%21%3
724
21st to endNight
23%22%32%18%4
792
February1st to 10thNight
28%23%28%19%2
720
11th to 20thNight
27%23%32%16%3
703
21st to endNight
22%18%36%18%6%
592
March1st to 10thNight
27%19%34%17%3
720
11th to 20thNight
24%17%33%19%6%
720
21st to endNight
24%19%33%18%6%1
792
April1st to 10thNight
30%14%34%19%3
610
11th to 20thNight
29%13%38%16%31
534
21st to endNight
31%10%29%21%8%1
540
May1st to 10thNight
31%10%34%19%5%1
540
11th to 20thNight
29%10%32%23%5%1
532
21st to endNight
30%7%30%24%7%1
583
June1st to 10thNight
29%7%34%25%5%
540
11th to 20thNight
25%7%31%30%7%
409
21st to endNight
34%227%28%8%1
360
July1st to 10thNight
29%227%32%9%
350
11th to 20thNight
26%329%31%11%
509
21st to endNight
29%427%32%7%
590
August1st to 10thNight
21%430%35%10%1
538
11th to 20thNight
23%6%23%34%13%1
532
21st to endNight
24%425%29%16%2
594
September1st to 10thNight
20%6%30%32%11%2
540
11th to 20thNight
24%6%26%26%15%3
697
21st to endNight
26%8%26%25%14%2
720
October1st to 10thNight
26%7%29%27%11%1
720
11th to 20thNight
23%15%26%24%9%2
720
21st to endNight
29%15%27%23%6%
792
November1st to 10thNight
25%14%27%25%9%1
767
11th to 20thNight
25%19%29%21%6%
850
21st to endNight
27%21%27%18%6%
850
December1st to 10thNight
31%17%29%18%5%
850
11th to 20thNight
32%23%28%14%2
850
21st to endNight
30%22%26%18%4
935
Page generated at 2024-01-08 12:14:18. Version ac07

Copyright 2024 Attilla Danko


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