Pelee Island
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pelee Island clear sky chart from 2005-11-05 to 2017-09-17.

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
42%
15504
14%
46839
11%
15466
45%
15466
19%
33692

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
20%
856
10%
2466
5%
855
24%
855
11%
1995
January16th to endNight
22%
768
8%
2496
3%
768
27%
768
9%
2036
February1st to 15thNight
22%
702
8%
2276
3%
701
28%
701
11%
1789
February16th to endNight
29%
631
12%
1893
6%
631
35%
631
14%
1443
March1st to 15thNight
35%
720
14%
2049
10%
720
38%
720
18%
1536
March16th to endNight
43%
768
16%
2112
11%
768
47%
768
22%
1512
April1st to 15thNight
40%
632
13%
1836
8%
632
44%
632
20%
1337
April16th to endNight
49%
540
20%
1620
10%
540
56%
540
25%
1074
May1st to 15thNight
47%
540
12%
1620
9%
540
49%
540
18%
1161
May16th to endNight
59%
561
15%
1684
14%
561
61%
561
27%
1086
June1st to 15thNight
60%
433
15%
1435
16%
433
62%
433
25%
898
June16th to endNight
65%
462
18%
1362
16%
462
68%
462
31%
839
July1st to 15thNight
67%
510
15%
1360
15%
510
67%
510
36%
849
July16th to endNight
74%
564
17%
1590
16%
531
75%
531
37%
930
August1st to 15thNight
72%
539
19%
1609
17%
536
72%
536
33%
962
August16th to endNight
68%
573
21%
1719
18%
573
70%
573
32%
1036
September1st to 15thNight
63%
699
21%
1950
17%
699
65%
699
31%
1246
September16th to endNight
58%
665
21%
1837
16%
665
61%
665
28%
1221
October1st to 15thNight
47%
660
18%
1916
17%
660
49%
660
24%
1303
October16th to endNight
29%
704
13%
2161
9%
704
34%
704
14%
1586
November1st to 15thNight
38%
700
17%
2276
16%
700
42%
700
19%
1586
November16th to endNight
25%
720
10%
2412
9%
720
27%
720
10%
1899
December1st to 15thNight
16%
720
5%
2520
3%
720
19%
720
6%
2114
December16th to endNight
17%
837
5%
2640
2%
837
21%
837
7%
2254

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
14%7%36%5%3445%7%36%
47899
Night
16%9%46%5%3445%6%32%
47021
Cloud CoverDay
14%7%36%5%3445%7%36%
47909
Night
16%9%46%5%34446%32%
47025
TransparencyDay
46%7%13%20%11%1
47599
Night
51%6%11%18%10%1
46839
SeeingDay
16%317%29%25%7%
5697
Night
20%5%22%29%17%4
15512

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
20%15%5%8%7%3435%419%
1468
16th to endDay
16%16%7%10%7%5%4346%16%
1728
February1st to 15thDay
16%12%5%9%8%44445%22%
1583
16th to endDay
14%10%49%9%45%5%46%25%
1580
March1st to 15thDay
18%10%47%5%35%45%6%28%
1900
16th to endDay
19%8%36%5%2445%8%31%
2112
April1st to 15thDay
15%8%36%5%35%5%5%7%33%
2121
16th to endDay
15%6%24425%447%41%
2340
May1st to 15thDay
15%6%35%6%445%46%35%
2331
16th to endDay
10%4245%2446%9%44%
2431
June1st to 15thDay
10%5%245%3447%8%44%
2513
16th to endDay
9%425%5%35%6%7%10%40%
2590
July1st to 15thDay
7%3245%345%6%8%48%
2520
16th to endDay
8%314425%46%9%48%
2468
August1st to 15thDay
6%4245%35%5%6%9%47%
2340
16th to endDay
9%4145%2446%9%46%
2483
September1st to 15thDay
12%6%2442445%7%43%
1997
16th to endDay
17%6%2432346%7%41%
1829
October1st to 15thDay
18%6%35%5%24446%37%
1713
16th to endDay
23%6%35%5%2345%6%32%
1709
November1st to 15thDay
14%9%46%424445%38%
1582
16th to endDay
19%15%47%6%2445%5%23%
1546
December1st to 15thDay
19%15%9%11%6%25%445%15%
1440
16th to endDay
20%16%5%11%7%3435%6%16%
1575
January1st to 15thNight
21%14%5%9%6%3433422%
2466
16th to endNight
17%15%7%9%7%35%435%20%
2496
February1st to 15thNight
17%13%5%9%6%35%44423%
2274
16th to endNight
18%9%5%9%5%45%445%27%
1893
March1st to 15thNight
18%10%46%5%3445%5%30%
2037
16th to endNight
14%9%37%6%35%446%34%
2112
April1st to 15thNight
18%7%45%6%35%45%5%33%
1836
16th to endNight
13%6%35%5%35%5%5%6%39%
1620
May1st to 15thNight
17%7%26%7%345%6%7%30%
1620
16th to endNight
11%425%5%345%5%7%42%
1682
June1st to 15thNight
11%425%5%25%5%6%6%43%
1435
16th to endNight
8%4245%35%46%10%43%
1362
July1st to 15thNight
8%424425%5%6%7%48%
1440
16th to endNight
6%314425%5%6%9%50%
1697
August1st to 15thNight
6%415%5%35%5%6%9%46%
1620
16th to endNight
9%5%245%245%5%6%48%
1719
September1st to 15thNight
12%5%13425%5%46%46%
1950
16th to endNight
14%5%25%5%35%446%43%
1837
October1st to 15thNight
18%8%25%5%23346%40%
1916
16th to endNight
23%8%36%5%25%445%29%
2161
November1st to 15thNight
16%10%46%5%23445%34%
2276
16th to endNight
25%14%46%5%33445%21%
2412
December1st to 15thNight
23%15%8%10%5%3333416%
2520
16th to endNight
24%15%6%8%7%34445%14%
2640

Percentage Cloud Cover SE (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
20%14%5%8%8%44445%19%
1468
16th to endDay
16%16%7%10%8%5%4345%16%
1728
February1st to 15thDay
16%12%5%9%8%5%445%5%22%
1583
16th to endDay
14%10%5%9%8%45%5%46%25%
1580
March1st to 15thDay
19%10%46%5%35%45%6%28%
1911
16th to endDay
19%8%36%5%2445%8%31%
2111
April1st to 15thDay
15%8%36%5%35%5%5%7%33%
2121
16th to endDay
15%6%34435%446%41%
2340
May1st to 15thDay
15%6%35%6%446%5%6%35%
2331
16th to endDay
10%4245%3446%9%44%
2431
June1st to 15thDay
9%4245%25%5%6%8%44%
2513
16th to endDay
9%325%5%35%6%7%10%40%
2590
July1st to 15thDay
7%4145%245%5%8%48%
2520
16th to endDay
7%325%425%5%6%8%48%
2468
August1st to 15thDay
6%414435%5%6%9%47%
2340
16th to endDay
9%32442446%9%46%
2483
September1st to 15thDay
12%6%2443445%7%43%
1997
16th to endDay
17%6%2432345%6%41%
1829
October1st to 15thDay
18%6%345%34446%37%
1713
16th to endDay
23%6%35%5%2445%6%32%
1709
November1st to 15thDay
14%9%46%424446%38%
1582
16th to endDay
19%15%5%6%6%34445%23%
1546
December1st to 15thDay
19%15%10%11%6%34345%15%
1440
16th to endDay
20%16%5%10%7%3435%5%16%
1575
January1st to 15thNight
21%14%49%6%33435%22%
2466
16th to endNight
17%16%7%9%8%35%445%19%
2496
February1st to 15thNight
16%13%5%9%7%45%44423%
2267
16th to endNight
18%9%5%9%5%45%445%27%
1893
March1st to 15thNight
18%10%47%6%34445%30%
2049
16th to endNight
14%9%37%5%45%346%35%
2112
April1st to 15thNight
18%8%36%5%35%45%6%32%
1836
16th to endNight
12%6%35%5%35%5%5%6%39%
1620
May1st to 15thNight
16%7%26%7%345%6%7%30%
1619
16th to endNight
11%435%5%345%5%7%42%
1682
June1st to 15thNight
11%425%5%25%5%5%6%43%
1435
16th to endNight
8%415%5%35%46%10%43%
1362
July1st to 15thNight
8%3245%25%5%6%7%48%
1440
16th to endNight
6%314425%5%6%9%50%
1697
August1st to 15thNight
6%415%5%35%5%6%9%46%
1620
16th to endNight
10%4245%245%5%6%47%
1719
September1st to 15thNight
12%5%24425%5%46%45%
1950
16th to endNight
14%5%25%5%35%446%43%
1837
October1st to 15thNight
18%8%25%5%23345%40%
1916
16th to endNight
24%8%36%5%34445%29%
2161
November1st to 15thNight
16%11%36%5%23445%34%
2276
16th to endNight
25%14%46%6%34445%20%
2412
December1st to 15thNight
23%16%9%10%5%2333415%
2520
16th to endNight
24%15%6%9%7%3444414%
2640

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
66%7%10%12%3
1469
16th to endDay
69%6%12%8%3
1728
February1st to 15thDay
62%5%11%14%5%
1585
16th to endDay
57%7%13%15%5%
1580
March1st to 15thDay
55%7%12%16%6%
1911
16th to endDay
49%6%12%22%7%1
2112
April1st to 15thDay
48%7%13%16%12%
2121
16th to endDay
42%6%12%21%12%4
2340
May1st to 15thDay
47%7%10%20%11%2
2331
16th to endDay
35%8%13%27%13%1
2435
June1st to 15thDay
35%8%14%26%13%1
2513
16th to endDay
35%9%14%21%16%2
2590
July1st to 15thDay
32%6%12%26%19%2
2371
16th to endDay
31%8%15%26%16%2
2312
August1st to 15thDay
30%7%15%30%13%1
2327
16th to endDay
31%8%16%24%15%3
2483
September1st to 15thDay
38%5%16%23%14%
1997
16th to endDay
41%6%11%25%15%
1829
October1st to 15thDay
46%6%11%21%12%1
1713
16th to endDay
51%7%15%17%7%
1709
November1st to 15thDay
46%6%12%19%14%1
1582
16th to endDay
61%6%12%14%4
1546
December1st to 15thDay
71%5%10%9%3
1440
16th to endDay
68%8%9%10%2
1575
January1st to 15thNight
65%5%9%14%5%
2466
16th to endNight
67%6%11%10%3
2496
February1st to 15thNight
63%6%10%14%5%
2276
16th to endNight
59%5%11%18%5%
1893
March1st to 15thNight
55%5%10%18%8%1
2049
16th to endNight
49%5%10%22%9%1
2112
April1st to 15thNight
51%6%10%17%13%
1836
16th to endNight
42%6%11%17%17%4
1620
May1st to 15thNight
49%8%11%17%10%2
1620
16th to endNight
38%7%10%24%15%2
1684
June1st to 15thNight
38%7%10%24%17%1
1435
16th to endNight
35%6%14%23%17%2
1362
July1st to 15thNight
32%7%12%25%19%2
1360
16th to endNight
28%8%15%25%18%4
1590
August1st to 15thNight
32%7%13%28%15%2
1609
16th to endNight
34%6%14%22%19%2
1719
September1st to 15thNight
37%6%12%23%16%3
1950
16th to endNight
41%5%10%23%18%1
1837
October1st to 15thNight
46%5%11%17%18%1
1916
16th to endNight
55%6%11%19%6%
2161
November1st to 15thNight
50%5%12%16%13%2
2276
16th to endNight
65%410%15%4
2412
December1st to 15thNight
72%5%9%8%4
2520
16th to endNight
73%5%10%8%2
2640

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
25%8%31%21%11%2
90
16th to endDay
29%5%30%27%8%
96
February1st to 15thDay
23%440%25%6%
90
16th to endDay
17%325%40%12%
81
March1st to 15thDay
27%5%24%30%11%
201
16th to endDay
23%326%32%11%2
288
April1st to 15thDay
17%5%24%36%13%1
270
16th to endDay
17%224%31%17%5%
270
May1st to 15thDay
18%320%32%21%2
288
16th to endDay
12%115%30%30%9%
331
June1st to 15thDay
13%12%38%29%5%
389
16th to endDay
13%113%35%29%6%
495
July1st to 15thDay
10%19%33%37%9%
475
16th to endDay
9%27%26%42%12%
328
August1st to 15thDay
9%8%31%37%12%
313
16th to endDay
9%210%24%40%12%
332
September1st to 15thDay
13%312%21%29%19%
315
16th to endDay
25%11%16%31%13%
259
October1st to 15thDay
21%316%20%25%11%
255
16th to endDay
23%6%30%28%9%
221
November1st to 15thDay
11%6%12%25%34%10%
90
16th to endDay
25%15%19%24%14%
77
December1st to 15thDay
16%21%26%26%8%
60
16th to endDay
31%442%19%2
83
January1st to 15thNight
29%9%32%21%6%
860
16th to endNight
22%8%34%26%7%
768
February1st to 15thNight
21%438%28%5%
704
16th to endNight
21%6%31%32%7%
631
March1st to 15thNight
23%427%33%10%
720
16th to endNight
17%425%34%12%4
768
April1st to 15thNight
21%6%25%36%9%1
632
16th to endNight
15%324%35%18%3
540
May1st to 15thNight
20%417%32%20%3
540
16th to endNight
14%213%32%26%11%
563
June1st to 15thNight
11%215%36%29%4
433
16th to endNight
11%13%37%32%5%
462
July1st to 15thNight
11%110%36%32%8%
510
16th to endNight
7%19%37%36%7%
564
August1st to 15thNight
9%110%38%30%10%
539
16th to endNight
12%19%28%37%10%
573
September1st to 15thNight
15%410%28%30%11%
699
16th to endNight
16%312%27%30%9%
665
October1st to 15thNight
24%417%24%22%6%
660
16th to endNight
27%10%27%25%7%
704
November1st to 15thNight
21%7%26%28%13%3
700
16th to endNight
32%12%25%19%9%1
720
December1st to 15thNight
31%11%30%19%6%
720
16th to endNight
30%8%33%21%5%
837
Page generated at 2017-09-18 08:38:22. Version ac04

Copyright 2017 A. Danko


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