West Palm Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the West Palm Beach clear sky chart from 2005-11-05 to 2018-04-23.

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%
17128
17%
49476
12%
17091
59%
17091
24%
32472

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
41%
777
16%
2522
10%
776
50%
776
20%
1615
January16th to endNight
42%
832
21%
2704
15%
832
51%
832
24%
1654
February1st to 15thNight
50%
761
24%
2281
19%
761
57%
761
29%
1368
February16th to endNight
51%
683
27%
1878
14%
683
63%
683
31%
1109
March1st to 15thNight
44%
780
25%
2145
14%
780
55%
780
32%
1278
March16th to endNight
52%
832
25%
2288
16%
832
59%
832
34%
1318
April1st to 15thNight
60%
778
24%
2122
17%
778
66%
778
39%
1191
April16th to endNight
54%
743
23%
1857
12%
743
60%
743
31%
1169
May1st to 15thNight
62%
719
22%
1799
13%
719
65%
719
37%
1093
May16th to endNight
60%
611
16%
1732
12%
611
61%
611
24%
1173
June1st to 15thNight
54%
540
9%
1620
5%
540
56%
540
16%
1202
June16th to endNight
64%
540
10%
1620
7%
540
65%
540
20%
1149
July1st to 15thNight
64%
510
5%
1530
4%
510
64%
510
17%
1131
July16th to endNight
65%
564
9%
1595
7%
531
70%
531
23%
1078
August1st to 15thNight
68%
617
7%
1687
6%
614
68%
614
26%
1150
August16th to endNight
61%
764
5%
1967
4%
764
61%
764
18%
1507
September1st to 15thNight
61%
720
4%
1980
4%
720
61%
720
16%
1533
September16th to endNight
54%
717
6%
1980
3%
717
57%
717
13%
1571
October1st to 15thNight
60%
720
17%
2112
17%
720
62%
720
21%
1450
October16th to endNight
50%
768
17%
2304
14%
768
55%
768
21%
1564
November1st to 15thNight
51%
760
21%
2281
19%
760
56%
760
26%
1438
November16th to endNight
45%
780
23%
2340
17%
780
53%
780
20%
1564
December1st to 15thNight
51%
780
22%
2428
18%
780
59%
780
25%
1527
December16th to endNight
57%
832
22%
2704
20%
832
63%
832
25%
1640

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
8%5%37%7%5%7%7%8%10%29%
50027
Night
7%425%6%36%6%7%10%38%
49679
TransparencyDay
45%11%15%15%9%2
49728
Night
36%10%17%20%11%3
49481
SeeingDay
9%8%13%23%25%20%
6868
Night
8%15%12%24%27%12%
17137

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%36%7%46%5%7%8%31%
1746
16th to endDay
9%5%37%7%36%5%6%9%35%
1872
February1st to 15thDay
10%5%35%5%35%5%7%8%38%
1905
16th to endDay
7%4246%45%46%8%42%
1881
March1st to 15thDay
5%425%5%46%6%7%9%41%
2145
16th to endDay
6%425%6%36%6%7%8%40%
2287
April1st to 15thDay
5%3145%36%7%9%11%39%
2156
16th to endDay
7%425%6%48%7%7%9%36%
2218
May1st to 15thDay
43245%46%5%8%11%42%
2152
16th to endDay
9%6%48%8%5%8%7%8%11%21%
2389
June1st to 15thDay
13%6%39%8%5%9%7%8%8%18%
2340
16th to endDay
7%6%38%8%6%9%9%8%10%21%
2340
July1st to 15thDay
7%8%37%8%6%9%10%10%10%18%
2340
16th to endDay
7%6%47%8%6%8%8%7%13%21%
2465
August1st to 15thDay
7%5%27%8%6%8%8%10%13%20%
2247
16th to endDay
10%5%39%8%6%7%7%8%10%20%
2229
September1st to 15thDay
8%7%37%8%6%8%9%10%11%17%
1980
16th to endDay
9%8%410%10%6%8%8%8%8%13%
1980
October1st to 15thDay
7%7%38%8%5%7%9%9%10%21%
1847
16th to endDay
12%6%38%7%5%5%7%8%8%26%
1920
November1st to 15thDay
8%5%35%6%47%6%6%8%37%
1907
16th to endDay
11%5%35%6%5%7%5%7%8%33%
1950
December1st to 15thDay
11%6%36%6%46%5%6%8%32%
1859
16th to endDay
8%436%5%36%7%7%10%36%
1872
January1st to 15thNight
9%5%35%6%35%6%8%9%37%
2522
16th to endNight
6%425%5%35%6%7%10%40%
2704
February1st to 15thNight
8%4245%2446%8%47%
2275
16th to endNight
4215%5%36%6%6%10%48%
1878
March1st to 15thNight
43245%35%5%6%8%50%
2145
16th to endNight
33145%35%47%11%49%
2288
April1st to 15thNight
211332447%11%55%
2122
16th to endNight
5%315%5%36%5%7%10%45%
1857
May1st to 15thNight
43244345%5%9%52%
1799
16th to endNight
8%436%6%36%7%8%11%34%
1732
June1st to 15thNight
10%7%47%7%37%7%9%11%24%
1620
16th to endNight
5%5%26%5%47%9%8%13%32%
1620
July1st to 15thNight
6%5%46%7%5%7%7%7%12%30%
1620
16th to endNight
4426%5%47%5%6%12%38%
1703
August1st to 15thNight
5%5%25%5%35%6%7%14%37%
1698
16th to endNight
7%5%27%7%46%7%9%11%29%
1967
September1st to 15thNight
6%5%28%8%47%9%9%14%23%
1980
16th to endNight
8%7%38%8%6%7%8%8%10%21%
1980
October1st to 15thNight
7%5%26%7%5%6%7%9%11%30%
2112
16th to endNight
13%5%25%6%35%5%6%10%32%
2304
November1st to 15thNight
7%5%26%5%37%6%7%10%39%
2281
16th to endNight
10%6%36%6%36%6%6%8%36%
2340
December1st to 15thNight
8%435%5%35%5%6%8%42%
2428
16th to endNight
5%4245%36%6%7%10%42%
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
46%9%11%14%13%4
1747
16th to endDay
41%7%11%19%14%6%
1872
February1st to 15thDay
39%6%11%20%15%6%
1907
16th to endDay
35%6%13%21%16%6%
1881
March1st to 15thDay
33%7%14%24%15%4
2145
16th to endDay
36%7%15%20%15%5%
2288
April1st to 15thDay
33%9%15%23%14%2
2156
16th to endDay
39%9%11%19%16%3
2218
May1st to 15thDay
33%7%15%23%14%5%
2152
16th to endDay
51%11%16%14%6%
2393
June1st to 15thDay
56%12%15%10%3
2340
16th to endDay
51%15%19%12%1
2340
July1st to 15thDay
54%18%18%8%
2201
16th to endDay
50%17%21%10%
2310
August1st to 15thDay
48%17%24%9%
2234
16th to endDay
52%17%20%9%
2229
September1st to 15thDay
53%20%17%7%
1980
16th to endDay
59%15%14%7%2
1980
October1st to 15thDay
48%12%13%15%8%1
1847
16th to endDay
50%9%10%11%11%5%
1920
November1st to 15thDay
40%8%11%18%15%5%
1907
16th to endDay
45%7%10%13%15%7%
1950
December1st to 15thDay
46%7%10%15%13%4
1859
16th to endDay
38%9%12%21%15%3
1872
January1st to 15thNight
39%8%17%19%11%3
2522
16th to endNight
35%8%14%22%12%6%
2704
February1st to 15thNight
32%7%12%24%17%6%
2283
16th to endNight
28%8%14%24%19%4
1878
March1st to 15thNight
29%7%14%25%17%6%
2145
16th to endNight
27%6%15%25%19%5%
2288
April1st to 15thNight
21%9%19%29%17%3
2122
16th to endNight
30%8%14%23%17%4
1857
May1st to 15thNight
26%7%14%32%13%5%
1800
16th to endNight
37%11%17%25%7%
1734
June1st to 15thNight
47%12%20%14%5%
1620
16th to endNight
38%16%28%15%1
1620
July1st to 15thNight
44%16%27%10%
1530
16th to endNight
35%14%32%15%1
1595
August1st to 15thNight
33%15%34%15%
1687
16th to endNight
43%19%25%10%
1967
September1st to 15thNight
45%19%24%9%1
1980
16th to endNight
50%16%20%9%2
1980
October1st to 15thNight
41%11%15%18%12%1
2112
16th to endNight
43%7%13%17%13%4
2304
November1st to 15thNight
37%7%12%20%17%5%
2281
16th to endNight
42%8%8%17%15%7%
2340
December1st to 15thNight
36%8%13%21%16%4
2428
16th to endNight
34%8%14%23%15%3
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
22%6%31%29%8%
135
16th to endDay
12%8%38%29%9%2
144
February1st to 15thDay
5%326%40%20%3
154
16th to endDay
10%11%21%32%22%2
291
March1st to 15thDay
412%31%32%15%2
330
16th to endDay
5%12%25%32%20%3
352
April1st to 15thDay
5%10%24%30%23%5%
330
16th to endDay
7%11%16%28%29%6%
289
May1st to 15thDay
5%10%12%25%30%14%
288
16th to endDay
7%10%5%19%34%22%
331
June1st to 15thDay
13%10%414%31%26%
315
16th to endDay
49%111%27%45%
315
July1st to 15thDay
36%17%29%50%
305
16th to endDay
7%9%17%31%42%
326
August1st to 15thDay
8%6%17%30%45%
313
16th to endDay
14%5%48%25%41%
332
September1st to 15thDay
8%5%313%24%44%
315
16th to endDay
10%5%415%27%37%
314
October1st to 15thDay
11%6%8%26%34%13%
315
16th to endDay
16%8%17%29%19%8%
336
November1st to 15thDay
11%8%14%29%27%9%
325
16th to endDay
9%10%21%37%19%1
330
December1st to 15thDay
16%7%15%35%19%4
239
16th to endDay
5%11%44%34%4
144
January1st to 15thNight
11%19%21%25%19%1
780
16th to endNight
8%19%23%32%14%
832
February1st to 15thNight
8%18%19%34%18%1
764
16th to endNight
7%16%21%33%20%
683
March1st to 15thNight
6%17%26%27%20%1
780
16th to endNight
6%17%18%36%19%1
832
April1st to 15thNight
316%14%37%24%2
778
16th to endNight
8%17%13%35%24%1
743
May1st to 15thNight
5%17%7%36%30%2
720
16th to endNight
7%18%5%20%36%11%
613
June1st to 15thNight
10%17%313%32%21%
540
16th to endNight
5%16%36%35%32%
540
July1st to 15thNight
7%12%15%35%36%
510
16th to endNight
5%16%6%31%39%
564
August1st to 15thNight
7%9%36%36%37%
617
16th to endNight
9%9%49%33%34%
764
September1st to 15thNight
9%8%39%35%32%
720
16th to endNight
14%8%410%34%27%
717
October1st to 15thNight
11%9%6%23%35%13%
720
16th to endNight
16%10%11%25%27%8%
768
November1st to 15thNight
8%14%18%24%29%4
760
16th to endNight
11%17%17%28%21%2
780
December1st to 15thNight
8%18%14%31%23%3
780
16th to endNight
7%17%11%29%29%4
832
Page generated at 2018-04-24 10:03:02. Version ac04

Copyright 2018 A. Danko


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