Tallahassee
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tallahassee clear sky chart from 2005-11-05 to 2018-02-14.

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
54%
16166
23%
48809
16%
16124
61%
16124
29%
29827

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
31%
780
22%
2522
10%
776
45%
776
22%
1553
January16th to endNight
34%
832
25%
2554
14%
832
45%
832
24%
1604
February1st to 15thNight
37%
758
25%
2278
12%
756
49%
756
26%
1413
February16th to endNight
34%
631
25%
1893
11%
631
45%
631
28%
1158
March1st to 15thNight
43%
720
28%
2048
16%
720
52%
720
34%
1210
March16th to endNight
45%
768
26%
2112
15%
768
53%
768
36%
1239
April1st to 15thNight
48%
682
25%
1940
17%
682
55%
682
34%
1145
April16th to endNight
55%
540
29%
1758
21%
540
65%
540
39%
920
May1st to 15thNight
63%
539
27%
1619
20%
539
68%
539
41%
897
May16th to endNight
71%
561
24%
1682
20%
561
74%
561
37%
977
June1st to 15thNight
73%
540
14%
1620
13%
540
74%
540
30%
1032
June16th to endNight
77%
540
13%
1620
12%
540
77%
540
27%
1065
July1st to 15thNight
80%
510
11%
1530
12%
510
80%
510
28%
997
July16th to endNight
78%
564
10%
1595
11%
531
78%
531
25%
1073
August1st to 15thNight
75%
539
9%
1747
10%
536
76%
536
22%
1181
August16th to endNight
72%
585
14%
1922
16%
585
72%
585
21%
1322
September1st to 15thNight
66%
720
12%
1980
11%
720
67%
720
20%
1439
September16th to endNight
61%
717
21%
1980
17%
717
65%
717
28%
1311
October1st to 15thNight
60%
720
31%
1980
24%
720
67%
720
40%
1136
October16th to endNight
56%
768
33%
2276
27%
768
65%
768
38%
1271
November1st to 15thNight
52%
760
30%
2379
24%
760
64%
760
37%
1286
November16th to endNight
47%
780
30%
2535
22%
780
59%
780
34%
1372
December1st to 15thNight
42%
780
25%
2535
19%
780
52%
780
27%
1505
December16th to endNight
39%
832
22%
2704
17%
832
48%
832
22%
1721

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
10%5%25%6%35%5%6%7%40%
49258
Night
9%4244245%6%8%46%
49011
TransparencyDay
40%8%12%15%15%7%
48959
Night
33%8%13%18%17%9%
48814
SeeingDay
11%6%19%23%23%15%
5962
Night
11%6%21%30%25%5%
16171

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
13%5%26%5%25%45%7%41%
1746
16th to endDay
15%425%423347%45%
2021
February1st to 15thDay
16%5%34323445%45%
1883
16th to endDay
15%6%14423335%50%
1580
March1st to 15thDay
9%4245%2345%7%50%
1911
16th to endDay
11%423424346%51%
2111
April1st to 15thDay
10%5%24434445%48%
2015
16th to endDay
8%31442445%8%51%
2202
May1st to 15thDay
7%5%135%25%5%6%8%48%
2331
16th to endDay
5%426%7%5%6%6%6%8%39%
2431
June1st to 15thDay
9%5%36%7%5%7%8%8%9%28%
2340
16th to endDay
7%427%8%5%9%8%9%9%26%
2340
July1st to 15thDay
7%5%36%9%5%9%9%9%10%23%
2340
16th to endDay
7%5%37%8%6%8%8%9%11%23%
2465
August1st to 15thDay
9%6%210%10%5%9%9%9%9%18%
2199
16th to endDay
10%7%37%7%5%7%8%6%9%24%
2268
September1st to 15thDay
10%7%37%7%5%7%7%7%9%26%
1980
16th to endDay
11%6%35%5%46%5%6%9%36%
1980
October1st to 15thDay
8%425%435%45%6%49%
1980
16th to endDay
7%5%25%32343456%
1947
November1st to 15thDay
7%313323446%59%
1806
16th to endDay
10%42342344454%
1755
December1st to 15thDay
14%5%25%414436%46%
1755
16th to endDay
18%7%25%5%34347%38%
1872
January1st to 15thNight
14%6%2442445%6%44%
2522
16th to endNight
15%6%34323346%45%
2554
February1st to 15thNight
14%5%24423345%49%
2271
16th to endNight
15%6%23423335%50%
1893
March1st to 15thNight
9%5%2432345%9%50%
2048
16th to endNight
9%423323447%55%
2112
April1st to 15thNight
10%3145%23447%51%
1940
16th to endNight
6%31331445%7%57%
1758
May1st to 15thNight
6%3132135%5%11%54%
1619
16th to endNight
33134346%7%10%50%
1682
June1st to 15thNight
6%414436%6%9%14%38%
1620
16th to endNight
6%4345%36%6%9%12%37%
1620
July1st to 15thNight
5%3135%35%7%10%13%39%
1620
16th to endNight
42245%37%8%10%14%35%
1703
August1st to 15thNight
6%325%6%46%8%11%16%29%
1758
16th to endNight
8%5%25%446%7%8%10%35%
1922
September1st to 15thNight
8%6%26%6%46%8%8%10%30%
1980
16th to endNight
6%6%25%5%35%7%7%10%39%
1980
October1st to 15thNight
5%41432345%8%54%
1980
16th to endNight
7%424323345%57%
2276
November1st to 15thNight
6%324433346%57%
2379
16th to endNight
10%423313436%56%
2535
December1st to 15thNight
12%5%24424447%48%
2535
16th to endNight
15%7%25%42435%6%41%
2704

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
42%5%9%14%17%11%
1747
16th to endDay
39%47%14%20%13%
2021
February1st to 15thDay
40%5%6%14%20%13%
1885
16th to endDay
37%47%13%24%12%
1580
March1st to 15thDay
32%49%18%24%10%
1911
16th to endDay
34%5%10%18%18%11%
2112
April1st to 15thDay
35%5%9%16%20%12%
2015
16th to endDay
29%5%11%22%19%11%
2202
May1st to 15thDay
32%8%11%17%21%9%
2331
16th to endDay
38%9%14%19%14%4
2435
June1st to 15thDay
45%13%17%16%6%
2340
16th to endDay
46%14%18%13%5%1
2340
July1st to 15thDay
49%16%20%12%2
2201
16th to endDay
48%16%20%11%2
2310
August1st to 15thDay
55%16%15%8%3
2186
16th to endDay
51%13%16%12%31
2268
September1st to 15thDay
50%13%15%11%6%1
1980
16th to endDay
42%8%14%16%12%5%
1980
October1st to 15thDay
34%7%9%15%21%11%
1980
16th to endDay
31%46%12%27%18%
1947
November1st to 15thDay
25%48%21%25%14%
1806
16th to endDay
31%5%6%17%24%15%
1755
December1st to 15thDay
38%5%11%16%18%9%
1755
16th to endDay
46%410%18%12%7%
1872
January1st to 15thNight
39%48%14%20%11%
2522
16th to endNight
40%46%12%23%12%
2554
February1st to 15thNight
37%46%14%21%14%
2280
16th to endNight
37%38%15%18%16%
1893
March1st to 15thNight
31%5%9%22%21%9%
2048
16th to endNight
29%5%11%18%23%11%
2112
April1st to 15thNight
32%5%9%18%23%11%
1940
16th to endNight
25%6%12%24%21%11%
1758
May1st to 15thNight
24%8%12%20%23%11%
1620
16th to endNight
24%11%17%23%17%5%
1684
June1st to 15thNight
31%12%24%20%9%1
1620
16th to endNight
33%14%22%19%9%1
1620
July1st to 15thNight
28%17%28%20%3
1530
16th to endNight
30%19%28%15%4
1595
August1st to 15thNight
34%17%28%16%2
1747
16th to endNight
37%16%22%17%41
1922
September1st to 15thNight
42%15%18%13%9%1
1980
16th to endNight
36%11%15%17%13%5%
1980
October1st to 15thNight
26%7%11%19%20%14%
1980
16th to endNight
28%46%14%24%21%
2276
November1st to 15thNight
27%47%20%24%15%
2379
16th to endNight
29%39%17%21%18%
2535
December1st to 15thNight
35%6%11%18%20%7%
2535
16th to endNight
42%48%21%13%8%
2704

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
14%20%42%12%5%4
135
16th to endDay
23%20%30%20%4
144
February1st to 15thDay
21%20%34%17%5%
130
16th to endDay
12%25%38%20%2
81
March1st to 15thDay
11%13%36%25%10%1
201
16th to endDay
13%10%30%23%19%2
288
April1st to 15thDay
11%15%22%26%21%1
270
16th to endDay
7%5%28%28%22%6%
270
May1st to 15thDay
10%5%22%29%19%12%
288
16th to endDay
8%216%29%23%19%
331
June1st to 15thDay
13%19%24%30%21%
315
16th to endDay
10%17%22%27%30%
315
July1st to 15thDay
7%5%15%31%39%
305
16th to endDay
5%5%19%33%35%
326
August1st to 15thDay
14%7%19%30%26%
313
16th to endDay
6%29%17%34%29%
332
September1st to 15thDay
17%212%20%25%22%
315
16th to endDay
14%12%22%35%14%
314
October1st to 15thDay
9%5%20%31%23%8%
315
16th to endDay
8%7%29%26%23%4
336
November1st to 15thDay
11%430%29%20%4
224
16th to endDay
7%11%39%23%13%4
135
December1st to 15thDay
20%10%33%25%8%1
135
16th to endDay
25%11%31%21%9%
144
January1st to 15thNight
17%14%31%24%10%1
780
16th to endNight
19%12%30%28%9%
832
February1st to 15thNight
17%11%30%30%10%
760
16th to endNight
18%11%32%33%4
631
March1st to 15thNight
12%11%28%34%11%
720
16th to endNight
12%9%29%32%16%
768
April1st to 15thNight
11%8%27%38%14%
682
16th to endNight
7%5%26%32%24%2
540
May1st to 15thNight
7%322%38%25%3
540
16th to endNight
5%213%37%35%6%
563
June1st to 15thNight
6%18%33%42%8%
540
16th to endNight
6%427%45%15%
540
July1st to 15thNight
5%419%47%21%
510
16th to endNight
5%319%50%20%
564
August1st to 15thNight
7%417%51%17%
539
16th to endNight
9%6%22%40%21%
585
September1st to 15thNight
11%17%26%38%14%
720
16th to endNight
9%214%33%34%5%
717
October1st to 15thNight
7%321%31%31%3
720
16th to endNight
8%6%23%33%25%2
768
November1st to 15thNight
8%6%27%35%19%2
760
16th to endNight
10%8%27%34%17%
780
December1st to 15thNight
13%9%28%29%17%1
780
16th to endNight
19%11%25%26%16%
832
Page generated at 2018-02-15 10:58:48. Version ac04

Copyright 2018 A. Danko


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