Largo
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Largo clear sky chart from 2005-11-05 to 2017-09-19.

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
61%
15840
21%
46992
17%
15801
66%
15801
31%
28989

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
46%
717
19%
2327
15%
716
53%
716
23%
1460
January16th to endNight
46%
768
25%
2373
19%
768
55%
768
29%
1447
February1st to 15thNight
47%
701
24%
2105
17%
699
55%
699
32%
1254
February16th to endNight
51%
631
24%
1877
15%
631
59%
631
33%
1110
March1st to 15thNight
52%
720
29%
1980
16%
720
62%
720
41%
1137
March16th to endNight
57%
768
27%
2112
20%
768
62%
768
41%
1213
April1st to 15thNight
62%
718
23%
1976
17%
718
66%
718
43%
1101
April16th to endNight
62%
681
27%
1863
19%
681
66%
681
41%
1081
May1st to 15thNight
75%
539
28%
1619
23%
539
79%
539
46%
837
May16th to endNight
77%
561
24%
1683
20%
561
79%
561
39%
981
June1st to 15thNight
71%
540
13%
1620
12%
540
71%
540
27%
1072
June16th to endNight
78%
540
9%
1620
8%
540
78%
540
27%
1084
July1st to 15thNight
76%
510
7%
1530
7%
510
76%
510
22%
1081
July16th to endNight
74%
564
7%
1595
7%
531
75%
531
23%
1111
August1st to 15thNight
79%
539
4%
1707
5%
536
79%
536
25%
1126
August16th to endNight
70%
678
9%
2015
10%
678
70%
678
22%
1407
September1st to 15thNight
67%
720
7%
1980
7%
720
67%
720
19%
1452
September16th to endNight
64%
673
13%
1858
12%
673
65%
673
23%
1329
October1st to 15thNight
70%
660
27%
1829
25%
660
73%
660
37%
1117
October16th to endNight
56%
704
26%
2112
23%
704
64%
704
33%
1259
November1st to 15thNight
60%
700
31%
2101
26%
700
68%
700
39%
1154
November16th to endNight
53%
720
29%
2274
23%
720
63%
720
34%
1315
December1st to 15thNight
51%
720
24%
2340
21%
720
58%
720
29%
1398
December16th to endNight
56%
768
24%
2496
24%
768
60%
768
29%
1463

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
7%425%5%35%6%7%10%40%
47806
Night
7%4245%35%5%6%9%44%
47198
TransparencyDay
35%9%16%19%14%4
47507
Night
33%7%17%20%15%5%
47001
SeeingDay
8%314%25%28%19%
5707
Night
8%316%32%27%11%
15849

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 15thDay
10%6%345%245%5%11%40%
1611
16th to endDay
11%33432436%7%47%
1848
February1st to 15thDay
12%5%2432445%6%47%
1750
16th to endDay
7%425%32335%7%54%
1595
March1st to 15thDay
422342445%9%56%
1980
16th to endDay
7%31442446%7%53%
2111
April1st to 15thDay
7%31343446%10%50%
1972
16th to endDay
5%22342446%8%54%
2104
May1st to 15thDay
5%21222346%8%59%
2331
16th to endDay
5%325%5%35%5%7%10%44%
2431
June1st to 15thDay
10%5%36%6%46%6%8%12%29%
2340
16th to endDay
7%435%6%47%7%10%13%28%
2340
July1st to 15thDay
8%426%8%5%9%8%11%12%22%
2340
16th to endDay
7%6%27%7%48%9%11%12%21%
2465
August1st to 15thDay
7%5%26%8%5%8%9%11%14%20%
2238
16th to endDay
9%5%26%8%5%7%8%9%12%23%
2175
September1st to 15thDay
9%5%36%6%47%8%10%11%25%
1980
16th to endDay
8%7%36%8%47%7%9%10%26%
1848
October1st to 15thDay
5%5%26%5%35%6%6%9%43%
1799
16th to endDay
9%42432445%9%49%
1760
November1st to 15thDay
6%3233346%5%8%51%
1757
16th to endDay
8%3235%245%49%49%
1683
December1st to 15thDay
8%6%25%43445%8%45%
1620
16th to endDay
7%4244245%5%7%49%
1728
January1st to 15thNight
9%6%36%6%35%45%8%40%
2327
16th to endNight
13%424425%5%5%8%43%
2373
February1st to 15thNight
11%6%24323446%50%
2103
16th to endNight
7%6%24434446%49%
1877
March1st to 15thNight
5%32442436%7%54%
1980
16th to endNight
6%31432445%7%54%
2112
April1st to 15thNight
6%3133235%6%9%53%
1976
16th to endNight
5%314424447%55%
1863
May1st to 15thNight
331232335%10%58%
1619
16th to endNight
4323325%6%6%8%52%
1682
June1st to 15thNight
10%435%5%246%7%11%38%
1620
16th to endNight
6%3145%36%7%9%12%37%
1620
July1st to 15thNight
5%425%5%48%7%9%13%33%
1620
16th to endNight
4426%7%46%8%10%14%30%
1703
August1st to 15thNight
5%325%5%37%7%9%13%35%
1718
16th to endNight
7%435%6%36%6%8%12%34%
2015
September1st to 15thNight
8%427%7%5%6%8%10%10%27%
1980
16th to endNight
8%6%36%8%36%7%7%9%32%
1858
October1st to 15thNight
6%4145%25%5%6%9%47%
1829
16th to endNight
8%5%24434348%48%
2112
November1st to 15thNight
6%32442445%8%52%
2101
16th to endNight
6%425%4345%6%9%47%
2274
December1st to 15thNight
10%435%435%45%8%44%
2340
16th to endNight
7%4246%35%5%6%8%45%
2496

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
38%5%11%24%15%4
1612
16th to endDay
34%48%20%24%7%
1848
February1st to 15thDay
36%47%16%21%12%
1752
16th to endDay
29%413%18%22%10%
1595
March1st to 15thDay
23%5%13%28%21%7%
1980
16th to endDay
30%411%25%21%7%
2112
April1st to 15thDay
26%7%15%22%21%6%
1972
16th to endDay
25%6%12%23%27%5%
2104
May1st to 15thDay
21%6%15%28%20%7%
2331
16th to endDay
30%10%14%25%17%1
2435
June1st to 15thDay
42%11%20%20%4
2340
16th to endDay
40%14%23%17%3
2340
July1st to 15thDay
45%17%27%8%1
2201
16th to endDay
45%16%25%11%1
2310
August1st to 15thDay
43%18%29%8%
2225
16th to endDay
45%17%24%11%
2175
September1st to 15thDay
45%15%24%13%2
1980
16th to endDay
45%12%14%18%6%1
1848
October1st to 15thDay
33%10%11%18%16%9%
1799
16th to endDay
31%6%9%18%22%11%
1760
November1st to 15thDay
29%5%7%25%23%7%
1757
16th to endDay
30%5%10%21%20%11%
1683
December1st to 15thDay
35%6%13%22%18%4
1620
16th to endDay
31%6%13%21%20%5%
1728
January1st to 15thNight
41%411%23%15%3
2327
16th to endNight
37%410%19%21%7%
2373
February1st to 15thNight
34%48%17%23%12%
2112
16th to endNight
32%5%13%18%22%8%
1877
March1st to 15thNight
27%5%12%28%19%6%
1980
16th to endNight
28%411%26%20%8%
2112
April1st to 15thNight
25%5%17%25%20%5%
1976
16th to endNight
28%412%24%24%5%
1863
May1st to 15thNight
21%6%13%31%20%7%
1620
16th to endNight
27%8%18%25%18%2
1684
June1st to 15thNight
38%9%22%22%6%
1620
16th to endNight
34%14%28%17%5%
1620
July1st to 15thNight
38%16%32%10%1
1530
16th to endNight
39%14%32%13%
1595
August1st to 15thNight
33%15%39%10%
1707
16th to endNight
40%13%28%15%1
2015
September1st to 15thNight
44%14%25%13%2
1980
16th to endNight
44%9%20%18%42
1858
October1st to 15thNight
30%7%13%20%20%7%
1829
16th to endNight
34%49%17%24%9%
2112
November1st to 15thNight
28%410%23%24%8%
2101
16th to endNight
32%49%23%17%12%
2274
December1st to 15thNight
36%5%12%25%15%3
2340
16th to endNight
33%6%13%22%17%6%
2496

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
13%11%31%27%15%1
90
16th to endDay
12%15%37%28%5%1
96
February1st to 15thDay
10%16%26%27%16%2
90
16th to endDay
6%6%43%35%8%
96
March1st to 15thDay
49%35%34%12%2
270
16th to endDay
8%8%24%35%19%3
288
April1st to 15thDay
8%426%32%23%4
270
16th to endDay
5%318%39%25%6%
270
May1st to 15thDay
6%218%35%22%14%
288
16th to endDay
5%28%29%33%20%
331
June1st to 15thDay
14%8%20%32%23%
315
16th to endDay
6%412%36%40%
315
July1st to 15thDay
48%32%51%
305
16th to endDay
11%3310%33%36%
326
August1st to 15thDay
9%37%37%40%
313
16th to endDay
9%414%34%35%
332
September1st to 15thDay
13%16%15%34%28%
315
16th to endDay
9%317%44%23%
266
October1st to 15thDay
7%310%34%32%10%
255
16th to endDay
11%418%33%26%5%
272
November1st to 15thDay
5%316%39%30%4
265
16th to endDay
7%229%37%19%3
153
December1st to 15thDay
8%334%40%12%1
90
16th to endDay
27%18%53%17%1
96
January1st to 15thNight
11%8%23%35%19%
720
16th to endNight
13%8%26%33%17%
768
February1st to 15thNight
13%5%27%37%14%
704
16th to endNight
9%7%27%41%14%
631
March1st to 15thNight
6%6%29%42%13%1
720
16th to endNight
7%425%41%20%1
768
April1st to 15thNight
6%320%45%21%1
718
16th to endNight
8%320%41%24%
681
May1st to 15thNight
4112%44%32%5%
540
16th to endNight
6%19%37%37%8%
563
June1st to 15thNight
10%2322%41%19%
540
16th to endNight
7%412%39%36%
540
July1st to 15thNight
6%26%41%42%
510
16th to endNight
5%38%37%44%
564
August1st to 15thNight
5%19%39%44%
539
16th to endNight
9%1316%36%31%
678
September1st to 15thNight
9%15%20%40%22%
720
16th to endNight
9%5%30%40%13%
673
October1st to 15thNight
8%19%39%33%7%
660
16th to endNight
11%319%34%27%3
704
November1st to 15thNight
6%422%40%24%3
700
16th to endNight
8%427%38%18%2
720
December1st to 15thNight
9%5%25%37%21%
720
16th to endNight
7%8%20%38%24%2
768
Page generated at 2017-09-20 04:49:54. Version ac04

Copyright 2017 A. Danko


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