St. James Plantation
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the St. James Plantation 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
51%
24783
20%
74339
14%
24732
57%
24732
27%
47268

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
32%
758
21%
2459
10%
757
47%
757
23%
1521
January11th to 20thNight
40%
737
24%
2393
14%
737
54%
737
24%
1486
January21st to endNight
33%
792
24%
2574
14%
792
47%
792
24%
1593
February1st to 10thNight
35%
720
19%
2340
13%
720
45%
720
25%
1456
February11th to 20thNight
32%
702
20%
2176
10%
699
45%
699
23%
1389
February21st to endNight
34%
592
23%
1655
13%
592
45%
592
24%
1104
March1st to 10thNight
39%
720
25%
1980
15%
720
49%
720
33%
1246
March11th to 20thNight
40%
720
18%
1980
11%
720
48%
720
25%
1339
March21st to endNight
42%
792
23%
2178
13%
792
50%
792
30%
1387
April1st to 10thNight
43%
720
22%
1845
11%
720
50%
720
35%
1155
April11th to 20thNight
50%
711
22%
1775
12%
711
54%
711
34%
1160
April21st to endNight
56%
720
26%
1800
15%
720
59%
720
43%
1086
May1st to 10thNight
55%
720
18%
1800
10%
720
57%
720
37%
1143
May11th to 20thNight
57%
536
16%
1598
11%
536
59%
536
27%
1025
May21st to endNight
67%
582
17%
1744
14%
582
68%
582
29%
1093
June1st to 10thNight
60%
540
14%
1620
12%
540
60%
540
24%
1083
June11th to 20thNight
67%
540
14%
1620
11%
540
68%
540
29%
1020
June21st to endNight
68%
540
12%
1620
11%
540
69%
540
22%
1090
July1st to 10thNight
70%
525
12%
1575
11%
525
71%
525
23%
1065
July11th to 20thNight
74%
522
10%
1566
9%
522
74%
522
25%
1025
July21st to endNight
69%
591
13%
1672
11%
558
70%
558
26%
1090
August1st to 10thNight
66%
537
10%
1600
7%
534
66%
534
24%
1074
August11th to 20thNight
68%
676
13%
1740
9%
676
68%
676
25%
1254
August21st to endNight
68%
792
12%
1980
8%
792
68%
792
25%
1452
September1st to 10thNight
68%
720
17%
1800
13%
720
68%
720
28%
1273
September11th to 20thNight
62%
720
17%
1858
14%
720
63%
720
26%
1319
September21st to endNight
56%
720
16%
2052
17%
720
57%
720
23%
1431
October1st to 10thNight
57%
720
20%
2160
21%
720
61%
720
28%
1383
October11th to 20thNight
58%
720
27%
2160
24%
720
66%
720
34%
1251
October21st to endNight
55%
792
29%
2376
24%
792
65%
792
35%
1345
November1st to 10thNight
54%
740
26%
2221
21%
740
62%
740
32%
1319
November11th to 20thNight
43%
760
26%
2280
17%
760
55%
760
27%
1429
November21st to endNight
47%
760
26%
2327
18%
760
57%
760
31%
1385
December1st to 10thNight
40%
760
21%
2470
12%
760
51%
760
21%
1623
December11th to 20thNight
41%
759
25%
2938
19%
758
50%
758
22%
1715
December21st to endNight
36%
827
16%
4407
15%
817
46%
817
15%
2459

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
11%5%25%5%35%5%6%8%44%
74925
Night
11%6%35%5%345%6%8%44%
74776
TransparencyDay
36%9%15%20%16%4
74647
Night
37%8%14%20%17%5%
74573
SeeingDay
13%6%20%29%24%8%
14589
Night
13%6%21%31%23%5%
24798

By Month

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 10thDay
14%6%345%2345%7%47%
1706
11th to 20thDay
12%6%37%4446%5%7%44%
1656
21st to endDay
16%6%35%434445%46%
1782
February1st to 10thDay
16%6%35%5%445%6%6%41%
1620
11th to 20thDay
18%6%345%24345%46%
1668
21st to endDay
14%7%36%425%5%6%6%43%
1596
March1st to 10thDay
13%5%34413346%53%
1980
11th to 20thDay
14%6%25%6%45%5%6%7%41%
1980
21st to endDay
12%436%6%45%5%6%7%43%
2178
April1st to 10thDay
10%42433446%7%53%
2114
11th to 20thDay
9%424435%5%5%7%53%
2134
21st to endDay
8%3233345%6%8%55%
2160
May1st to 10thDay
6%3245%345%6%8%53%
2168
11th to 20thDay
11%5%25%5%35%46%8%45%
2301
21st to endDay
9%5%25%5%35%6%7%10%43%
2531
June1st to 10thDay
10%7%27%6%45%6%7%10%36%
2340
11th to 20thDay
9%4345%35%6%9%13%40%
2340
21st to endDay
7%5%35%6%46%6%8%12%37%
2340
July1st to 10thDay
9%5%36%6%45%7%8%13%35%
2340
11th to 20thDay
7%5%26%6%47%7%8%12%37%
2340
21st to endDay
7%5%36%6%46%6%8%12%37%
2547
August1st to 10thDay
11%6%25%6%45%7%8%14%32%
2327
11th to 20thDay
10%6%35%5%35%6%9%12%35%
2143
21st to endDay
9%6%37%6%5%6%6%8%11%32%
2376
September1st to 10thDay
10%5%25%5%46%5%7%10%41%
2160
11th to 20thDay
13%6%36%5%35%5%6%8%40%
2098
21st to endDay
15%7%36%6%35%45%6%39%
1908
October1st to 10thDay
12%5%35%6%45%5%5%6%45%
1800
11th to 20thDay
9%5%15%5%24445%56%
1800
21st to endDay
9%425%42345%5%57%
1980
November1st to 10thDay
11%5%3442345%6%54%
1857
11th to 20thDay
12%435%5%34346%51%
1900
21st to endDay
10%5%25%434347%52%
1848
December1st to 10thDay
15%5%36%446%6%5%7%38%
1630
11th to 20thDay
15%5%24333445%54%
2153
21st to endDay
14%9%35%4345%6%6%41%
3124
January1st to 10thNight
12%7%36%5%3445%6%46%
2459
11th to 20thNight
10%6%35%5%35%5%5%7%46%
2393
21st to endNight
15%5%35%435%45%6%46%
2574
February1st to 10thNight
17%6%25%5%3435%6%44%
2340
11th to 20thNight
17%8%25%42346%6%43%
2176
21st to endNight
15%6%36%5%345%5%6%41%
1655
March1st to 10thNight
12%5%25%43445%7%49%
1980
11th to 20thNight
12%5%47%6%35%6%6%7%40%
1980
21st to endNight
12%6%35%33445%8%47%
2178
April1st to 10thNight
10%6%245%2346%7%50%
1845
11th to 20thNight
10%425%5%35%5%5%6%48%
1775
21st to endNight
7%32443446%8%55%
1800
May1st to 10thNight
7%4244446%6%10%48%
1800
11th to 20thNight
11%6%35%5%35%5%5%9%44%
1597
21st to endNight
10%5%345%35%5%6%10%45%
1744
June1st to 10thNight
10%6%37%5%35%5%8%11%35%
1620
11th to 20thNight
9%4346%35%5%7%12%42%
1620
21st to endNight
8%5%25%7%45%7%10%15%33%
1620
July1st to 10thNight
6%5%26%7%5%6%7%7%12%36%
1620
11th to 20thNight
7%5%35%437%8%9%12%37%
1620
21st to endNight
7%5%36%6%36%7%8%12%38%
1771
August1st to 10thNight
8%6%45%6%35%7%8%12%37%
1611
11th to 20thNight
8%5%36%7%5%6%7%8%11%34%
1740
21st to endNight
10%6%25%6%45%7%9%11%34%
1980
September1st to 10thNight
9%5%25%6%46%6%7%11%39%
1800
11th to 20thNight
11%6%35%7%36%5%8%9%37%
1858
21st to endNight
17%7%35%5%3445%8%39%
2052
October1st to 10thNight
11%6%35%6%35%447%46%
2160
11th to 20thNight
9%4243345%5%7%53%
2160
21st to endNight
9%5%25%5%34347%55%
2376
November1st to 10thNight
11%5%24434445%54%
2221
11th to 20thNight
11%7%25%5%3345%6%48%
2280
21st to endNight
10%5%35%5%3446%8%49%
2327
December1st to 10thNight
15%8%25%5%345%48%40%
2470
11th to 20thNight
15%6%3442335%5%49%
3042
21st to endNight
15%7%35%5%2445%6%45%
4532

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
37%7%12%18%20%7%
1707
11th to 20thDay
40%7%9%16%23%6%
1656
21st to endDay
41%46%20%22%6%
1782
February1st to 10thDay
42%6%11%20%17%4
1620
11th to 20thDay
42%5%8%18%21%7%
1677
21st to endDay
39%7%11%18%16%9%
1596
March1st to 10thDay
33%5%11%20%23%8%
1980
11th to 20thDay
41%7%13%19%16%5%
1980
21st to endDay
38%8%13%20%16%5%
2178
April1st to 10thDay
29%6%15%22%23%6%
2114
11th to 20thDay
29%6%14%24%18%9%
2134
21st to endDay
26%9%14%25%23%4
2160
May1st to 10thDay
29%7%17%27%17%3
2168
11th to 20thDay
35%9%18%24%14%1
2305
21st to endDay
33%11%21%22%12%
2531
June1st to 10thDay
41%11%16%22%10%
2340
11th to 20thDay
32%13%22%23%10%
2340
21st to endDay
35%14%22%20%8%1
2340
July1st to 10thDay
37%13%23%20%6%1
2275
11th to 20thDay
34%15%25%19%6%
2271
21st to endDay
34%13%25%24%4
2405
August1st to 10thDay
39%13%26%19%3
2314
11th to 20thDay
38%14%24%17%6%
2143
21st to endDay
41%14%23%17%41
2376
September1st to 10thDay
36%13%19%17%12%3
2160
11th to 20thDay
41%11%14%16%15%4
2098
21st to endDay
44%8%12%18%15%3
1908
October1st to 10thDay
39%7%11%19%21%3
1800
11th to 20thDay
30%6%11%23%23%7%
1800
21st to endDay
29%6%9%20%27%8%
1980
November1st to 10thDay
32%5%9%19%26%9%
1857
11th to 20thDay
36%7%8%17%23%8%
1900
21st to endDay
33%7%9%21%23%7%
1848
December1st to 10thDay
43%9%12%17%13%6%
1630
11th to 20thDay
34%5%7%21%24%9%
2150
21st to endDay
42%6%12%19%18%3
3124
January1st to 10thNight
39%7%10%20%19%6%
2459
11th to 20thNight
38%7%10%17%22%6%
2393
21st to endNight
39%5%7%19%23%6%
2574
February1st to 10thNight
41%410%18%20%7%
2340
11th to 20thNight
41%6%10%16%20%8%
2178
21st to endNight
43%5%10%18%14%9%
1655
March1st to 10thNight
34%6%10%20%20%9%
1980
11th to 20thNight
41%8%14%16%16%5%
1980
21st to endNight
36%7%13%23%16%5%
2178
April1st to 10thNight
33%6%14%17%23%7%
1845
11th to 20thNight
35%6%12%21%17%9%
1775
21st to endNight
26%7%15%28%20%4
1800
May1st to 10thNight
31%8%16%22%19%3
1800
11th to 20thNight
37%9%17%22%14%1
1598
21st to endNight
33%12%17%26%11%1
1745
June1st to 10thNight
42%9%20%21%9%
1620
11th to 20thNight
33%12%21%25%8%
1620
21st to endNight
36%16%20%21%6%
1620
July1st to 10thNight
37%14%21%18%8%1
1575
11th to 20thNight
33%15%27%19%5%
1566
21st to endNight
34%14%23%25%4
1672
August1st to 10thNight
36%14%26%20%4
1600
11th to 20thNight
39%15%22%19%5%
1740
21st to endNight
39%16%21%18%6%1
1980
September1st to 10thNight
37%13%19%16%12%2
1800
11th to 20thNight
42%10%15%17%13%2
1858
21st to endNight
45%8%13%19%13%2
2052
October1st to 10thNight
39%7%13%18%18%5%
2160
11th to 20thNight
30%7%12%21%23%7%
2160
21st to endNight
30%5%10%19%26%10%
2376
November1st to 10thNight
32%7%9%17%25%10%
2221
11th to 20thNight
38%6%9%15%23%9%
2280
21st to endNight
34%6%10%21%22%6%
2327
December1st to 10thNight
43%7%12%16%16%5%
2470
11th to 20thNight
38%5%8%19%24%7%
3044
21st to endNight
40%5%9%21%21%3
4532

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
17%12%39%25%7%
270
11th to 20thDay
14%8%30%38%10%
252
21st to endDay
19%14%31%29%6%1
264
February1st to 10thDay
17%12%33%32%5%
240
11th to 20thDay
24%10%33%27%5%
335
21st to endDay
14%12%37%27%8%1
346
March1st to 10thDay
12%9%35%31%11%1
420
11th to 20thDay
15%12%37%27%8%1
420
21st to endDay
13%10%35%29%11%2
462
April1st to 10thDay
13%12%28%30%16%2
420
11th to 20thDay
11%7%26%29%21%6%
412
21st to endDay
8%7%23%35%22%6%
420
May1st to 10thDay
5%8%31%32%18%6%
423
11th to 20thDay
13%314%36%28%6%
447
21st to endDay
13%411%28%28%16%
485
June1st to 10thDay
13%414%31%30%9%
450
11th to 20thDay
12%112%25%33%17%
450
21st to endDay
9%29%32%37%11%
450
July1st to 10thDay
10%25%27%41%16%
445
11th to 20thDay
9%17%24%44%15%
444
21st to endDay
7%17%30%44%11%
488
August1st to 10thDay
13%27%26%39%14%
446
11th to 20thDay
10%2425%39%20%
439
21st to endDay
11%37%23%39%18%
495
September1st to 10thDay
8%28%27%37%18%
450
11th to 20thDay
17%212%27%32%10%
450
21st to endDay
18%211%27%30%12%
450
October1st to 10thDay
14%5%18%28%25%11%
450
11th to 20thDay
9%419%33%28%8%
450
21st to endDay
10%6%22%33%24%5%
495
November1st to 10thDay
14%5%21%32%22%6%
455
11th to 20thDay
14%7%31%32%15%1
460
21st to endDay
10%8%30%32%17%3
408
December1st to 10thDay
22%7%26%29%15%1
231
11th to 20thDay
17%10%28%29%14%2
270
21st to endDay
18%14%27%27%11%4
297
January1st to 10thNight
16%13%34%30%8%
760
11th to 20thNight
14%10%29%36%11%
737
21st to endNight
16%10%36%32%5%
792
February1st to 10thNight
20%8%32%32%8%
720
11th to 20thNight
21%13%31%31%4
703
21st to endNight
19%9%31%31%10%
592
March1st to 10thNight
13%10%33%32%11%1
720
11th to 20thNight
14%10%30%35%10%2
720
21st to endNight
15%8%30%31%14%1
792
April1st to 10thNight
12%9%30%33%15%1
720
11th to 20thNight
12%7%26%30%21%4
711
21st to endNight
7%5%28%35%22%2
720
May1st to 10thNight
8%8%24%37%22%2
720
11th to 20thNight
15%417%30%29%4
536
21st to endNight
11%39%27%35%15%
584
June1st to 10thNight
10%412%36%33%6%
540
11th to 20thNight
12%29%27%37%13%
540
21st to endNight
9%38%35%37%9%
540
July1st to 10thNight
7%26%28%47%9%
525
11th to 20thNight
10%1327%46%13%
522
21st to endNight
8%36%30%43%11%
591
August1st to 10thNight
11%27%26%42%12%
537
11th to 20thNight
10%17%25%44%13%
676
21st to endNight
12%26%23%42%15%
792
September1st to 10thNight
10%27%26%42%13%
720
11th to 20thNight
14%110%31%34%9%
720
21st to endNight
20%312%27%29%9%
720
October1st to 10thNight
13%418%30%27%9%
720
11th to 20thNight
12%421%33%24%6%
720
21st to endNight
12%7%19%32%25%6%
792
November1st to 10thNight
13%6%23%33%21%4
740
11th to 20thNight
14%10%28%29%18%2
760
21st to endNight
12%7%28%32%18%3
760
December1st to 10thNight
18%8%28%32%13%1
760
11th to 20thNight
17%9%28%31%14%1
760
21st to endNight
19%9%29%29%13%1
836
Page generated at 2024-01-11 22:33:50. Version ac07

Copyright 2024 Attilla Danko


St. James Plantation Clear Sky Chart |Charts Home