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 2005-11-06 to 2024-01-12.

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
63%
25003
11%
74490
9%
24947
65%
24947
14%
57719

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
55%
758
13%
2459
10%
757
60%
757
16%
1782
January11th to 20thNight
52%
727
12%
2360
10%
727
57%
727
12%
1810
January21st to endNight
46%
792
13%
2574
10%
792
51%
792
14%
1922
February1st to 10thNight
55%
720
16%
2175
14%
720
58%
720
15%
1630
February11th to 20thNight
57%
700
16%
1980
11%
699
63%
699
18%
1457
February21st to endNight
63%
592
21%
1628
16%
592
67%
592
22%
1147
March1st to 10thNight
54%
720
18%
1980
11%
720
59%
720
22%
1404
March11th to 20thNight
61%
720
17%
1980
11%
720
65%
720
22%
1412
March21st to endNight
62%
792
19%
2178
15%
792
66%
792
23%
1519
April1st to 10thNight
67%
720
15%
1980
12%
720
69%
720
22%
1435
April11th to 20thNight
62%
711
14%
1839
9%
711
64%
711
19%
1391
April21st to endNight
65%
720
16%
1800
10%
720
67%
720
20%
1368
May1st to 10thNight
74%
720
16%
1800
11%
720
75%
720
26%
1279
May11th to 20thNight
63%
701
9%
1762
5%
701
65%
701
17%
1394
May21st to endNight
69%
582
7%
1744
7%
582
69%
582
13%
1412
June1st to 10thNight
63%
540
7%
1620
5%
540
63%
540
9%
1362
June11th to 20thNight
72%
540
7%
1620
6%
540
72%
540
14%
1295
June21st to endNight
75%
540
6%
1620
5%
540
75%
540
11%
1364
July1st to 10thNight
73%
525
2%
1575
2%
525
73%
525
8%
1337
July11th to 20thNight
76%
522
4%
1566
4%
522
76%
522
10%
1300
July21st to endNight
76%
591
5%
1672
5%
558
77%
558
12%
1358
August1st to 10thNight
73%
563
5%
1626
4%
560
74%
560
15%
1275
August11th to 20thNight
78%
710
4%
1774
4%
710
78%
710
15%
1446
August21st to endNight
66%
792
3%
2066
3%
792
66%
792
10%
1759
September1st to 10thNight
65%
720
4%
1980
4%
720
65%
720
10%
1650
September11th to 20thNight
66%
720
3%
1980
3%
720
66%
720
9%
1690
September21st to endNight
60%
720
5%
1980
6%
720
60%
720
8%
1726
October1st to 10thNight
62%
720
10%
2088
11%
720
63%
720
13%
1655
October11th to 20thNight
66%
720
12%
2160
11%
720
68%
720
14%
1683
October21st to endNight
61%
792
12%
2376
12%
792
63%
792
15%
1829
November1st to 10thNight
55%
740
15%
2221
12%
740
60%
740
15%
1683
November11th to 20thNight
56%
760
14%
2280
13%
760
59%
760
15%
1759
November21st to endNight
53%
760
13%
2280
11%
760
56%
760
13%
1782
December1st to 10thNight
63%
760
16%
2313
14%
760
67%
760
15%
1748
December11th to 20thNight
55%
760
11%
2974
11%
758
57%
758
9%
2294
December21st to endNight
56%
833
9%
4480
13%
817
60%
817
8%
3362

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%6%37%7%5%7%7%8%11%32%
74896
Night
7%5%36%6%46%6%7%10%40%
74819
TransparencyDay
29%42%10%11%7%2
74619
Night
25%41%12%13%8%2
74615
SeeingDay
8%315%27%29%18%
14845
Night
9%315%29%31%13%
25013

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
9%5%26%7%45%6%7%9%40%
1706
11th to 20thDay
8%6%36%6%47%6%7%10%37%
1629
21st to endDay
10%5%37%7%36%7%6%9%36%
1782
February1st to 10thDay
11%5%45%6%35%5%7%9%39%
1782
11th to 20thDay
7%4246%35%5%6%9%49%
1864
21st to endDay
8%5%35%6%46%6%7%9%42%
1628
March1st to 10thDay
4425%6%47%7%7%10%44%
1980
11th to 20thDay
6%5%25%5%35%6%8%9%46%
1980
21st to endDay
5%425%6%36%6%7%9%46%
2178
April1st to 10thDay
5%4145%36%7%9%11%44%
1980
11th to 20thDay
8%5%26%5%5%6%8%9%10%36%
2070
21st to endDay
6%4246%48%7%7%9%43%
2160
May1st to 10thDay
4213436%6%9%12%49%
2160
11th to 20thDay
10%7%37%7%5%7%7%7%10%29%
2144
21st to endDay
10%6%48%8%5%8%7%8%11%26%
2531
June1st to 10thDay
15%7%49%8%6%8%8%8%11%17%
2340
11th to 20thDay
7%6%48%10%5%9%8%9%11%23%
2340
21st to endDay
7%6%39%7%6%9%9%9%11%25%
2340
July1st to 10thDay
6%7%37%9%6%9%10%11%12%20%
2340
11th to 20thDay
7%7%36%7%6%8%9%9%14%24%
2340
21st to endDay
6%6%37%8%6%9%8%9%13%25%
2547
August1st to 10thDay
7%5%27%8%5%9%9%10%15%23%
2279
11th to 20thDay
5%5%27%8%6%8%8%10%14%26%
2126
21st to endDay
9%5%39%8%5%8%9%9%13%21%
2283
September1st to 10thDay
8%7%37%8%6%9%9%10%13%20%
1980
11th to 20thDay
7%6%37%9%7%9%9%9%12%21%
1980
21st to endDay
10%8%410%10%6%7%9%8%10%18%
1980
October1st to 10thDay
8%8%48%8%47%10%10%11%23%
1871
11th to 20thDay
8%6%38%8%5%6%7%9%11%30%
1800
21st to endDay
10%6%37%7%5%6%8%8%10%32%
1980
November1st to 10thDay
8%5%35%6%46%7%8%9%38%
1857
11th to 20thDay
12%6%36%7%5%7%6%7%9%32%
1900
21st to endDay
8%5%35%6%47%7%6%11%37%
1900
December1st to 10thDay
9%6%36%6%46%6%7%10%38%
1862
11th to 20thDay
11%6%36%6%36%6%6%8%39%
2153
21st to endDay
13%7%37%7%46%8%7%10%29%
3124
January1st to 10thNight
8%4245%345%7%10%46%
2459
11th to 20thNight
9%6%35%5%46%5%8%9%41%
2360
21st to endNight
9%5%36%5%45%6%7%11%40%
2574
February1st to 10thNight
9%5%35%6%25%5%6%10%44%
2175
11th to 20thNight
7%4245%3446%9%53%
1980
21st to endNight
6%3245%45%6%6%9%50%
1628
March1st to 10thNight
43245%45%45%8%56%
1980
11th to 20thNight
6%3145%25%5%6%8%53%
1980
21st to endNight
4425%435%47%11%51%
2178
April1st to 10thNight
432343447%10%56%
1980
11th to 20thNight
5%325%6%46%6%7%11%45%
1839
21st to endNight
5%4145%36%6%8%10%48%
1800
May1st to 10thNight
43244245%5%10%57%
1800
11th to 20thNight
8%5%35%6%46%6%7%12%37%
1762
21st to endNight
8%5%36%6%46%6%8%11%38%
1744
June1st to 10thNight
10%8%47%7%49%8%9%10%24%
1620
11th to 20thNight
7%7%37%7%46%8%10%12%31%
1620
21st to endNight
5%6%26%5%5%8%8%8%14%32%
1620
July1st to 10thNight
6%5%45%7%47%9%9%14%32%
1620
11th to 20thNight
5%425%7%6%7%8%8%14%35%
1620
21st to endNight
35%28%6%47%6%8%12%38%
1771
August1st to 10thNight
6%5%35%6%45%6%8%15%37%
1637
11th to 20thNight
3425%6%46%7%9%14%40%
1774
21st to endNight
7%6%38%7%5%7%7%9%12%29%
2066
September1st to 10thNight
8%5%38%8%5%7%10%9%13%26%
1980
11th to 20thNight
6%7%38%8%5%6%7%9%12%29%
1980
21st to endNight
9%7%48%8%6%8%8%9%10%24%
1980
October1st to 10thNight
9%6%38%7%5%6%6%9%11%30%
2088
11th to 20thNight
8%6%26%6%46%6%8%9%38%
2160
21st to endNight
11%6%35%6%46%6%7%11%36%
2376
November1st to 10thNight
9%6%25%6%45%5%7%11%39%
2221
11th to 20thNight
8%6%36%6%47%6%8%9%37%
2280
21st to endNight
9%6%46%6%36%6%6%9%39%
2280
December1st to 10thNight
7%425%6%45%5%7%9%46%
2313
11th to 20thNight
14%6%35%5%345%5%8%42%
3042
21st to endNight
10%8%38%8%5%6%6%7%9%30%
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
23%42%7%12%13%4
1707
11th to 20thDay
25%44%8%12%7%4
1629
21st to endDay
28%40%6%12%10%4
1782
February1st to 10thDay
26%38%6%14%11%4
1782
11th to 20thDay
22%40%7%18%9%4
1874
21st to endDay
22%38%8%12%15%5%
1628
March1st to 10thDay
19%40%9%16%13%3
1980
11th to 20thDay
21%39%8%18%10%3
1980
21st to endDay
19%38%10%19%12%3
2178
April1st to 10thDay
21%41%9%16%11%2
1980
11th to 20thDay
27%39%10%14%9%2
2070
21st to endDay
24%40%8%14%11%3
2160
May1st to 10thDay
14%40%12%20%13%1
2160
11th to 20thDay
30%41%12%11%5%
2148
21st to endDay
34%42%11%10%4
2531
June1st to 10thDay
38%42%11%7%2
2340
11th to 20thDay
32%42%13%11%1
2340
21st to endDay
37%43%12%7%1
2340
July1st to 10thDay
36%47%13%41
2275
11th to 20thDay
33%47%14%6%
2271
21st to endDay
31%48%13%8%
2405
August1st to 10thDay
31%46%16%6%
2266
11th to 20thDay
30%45%17%8%
2126
21st to endDay
33%48%13%5%1
2283
September1st to 10thDay
31%47%13%8%1
1980
11th to 20thDay
35%46%11%6%1
1980
21st to endDay
39%42%9%6%31
1980
October1st to 10thDay
30%43%9%10%6%1
1871
11th to 20thDay
29%40%12%12%6%1
1800
21st to endDay
28%40%7%11%11%2
1980
November1st to 10thDay
24%42%6%10%12%7%
1857
11th to 20thDay
28%42%8%12%9%3
1900
21st to endDay
24%43%9%11%11%1
1900
December1st to 10thDay
24%43%8%13%10%2
1862
11th to 20thDay
32%35%6%10%12%5%
2150
21st to endDay
35%32%9%10%12%3
3124
January1st to 10thNight
19%41%10%14%12%4
2459
11th to 20thNight
23%43%8%13%10%3
2360
21st to endNight
22%41%10%15%7%5%
2574
February1st to 10thNight
25%38%7%15%11%4
2175
11th to 20thNight
19%40%9%20%10%2
1981
21st to endNight
17%37%10%16%17%3
1628
March1st to 10thNight
16%38%9%18%15%4
1980
11th to 20thNight
16%39%13%19%10%3
1980
21st to endNight
16%37%10%21%13%3
2178
April1st to 10thNight
16%40%13%17%11%3
1980
11th to 20thNight
21%40%11%17%11%1
1839
21st to endNight
21%40%9%16%13%3
1800
May1st to 10thNight
13%39%10%26%12%1
1800
11th to 20thNight
23%43%13%16%6%
1763
21st to endNight
28%42%13%13%3
1745
June1st to 10thNight
33%43%12%9%3
1620
11th to 20thNight
26%43%18%12%1
1620
21st to endNight
31%44%15%8%1
1620
July1st to 10thNight
32%46%16%6%1
1575
11th to 20thNight
30%44%19%7%
1566
21st to endNight
24%47%19%9%1
1672
August1st to 10thNight
22%44%23%11%
1626
11th to 20thNight
24%45%22%8%
1774
21st to endNight
29%47%16%6%2
2066
September1st to 10thNight
29%45%16%9%1
1980
11th to 20thNight
33%45%14%8%1
1980
21st to endNight
36%44%10%6%3
1980
October1st to 10thNight
28%41%11%13%7%1
2088
11th to 20thNight
27%40%10%15%7%1
2160
21st to endNight
25%39%9%14%10%2
2376
November1st to 10thNight
21%43%7%10%13%6%
2221
11th to 20thNight
23%42%9%15%9%2
2280
21st to endNight
24%43%8%13%10%2
2280
December1st to 10thNight
20%44%9%16%9%3
2313
11th to 20thNight
32%36%7%11%8%7%
3044
21st to endNight
36%32%9%9%11%4
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
11%6%32%37%12%1
270
11th to 20thDay
9%6%32%35%17%2
243
21st to endDay
12%10%34%34%9%
264
February1st to 10thDay
6%6%30%37%18%3
240
11th to 20thDay
7%423%42%20%4
357
21st to endDay
9%421%36%29%1
346
March1st to 10thDay
45%32%38%19%2
420
11th to 20thDay
7%6%25%37%23%2
420
21st to endDay
3325%40%24%3
462
April1st to 10thDay
5%430%38%19%5%
420
11th to 20thDay
9%5%22%37%23%4
412
21st to endDay
7%217%40%30%4
420
May1st to 10thDay
4114%39%32%10%
423
11th to 20thDay
11%214%31%30%12%
447
21st to endDay
12%19%20%39%20%
485
June1st to 10thDay
13%28%22%36%20%
450
11th to 20thDay
8%3415%36%34%
450
21st to endDay
4311%36%46%
450
July1st to 10thDay
41310%33%49%
445
11th to 20thDay
6%37%39%45%
444
21st to endDay
5%411%38%41%
488
August1st to 10thDay
6%2411%36%41%
446
11th to 20thDay
5%37%39%46%
439
21st to endDay
10%416%36%33%
495
September1st to 10thDay
8%2412%34%40%
450
11th to 20thDay
5%16%16%35%38%
450
21st to endDay
12%18%18%34%27%
450
October1st to 10thDay
12%29%32%35%11%
450
11th to 20thDay
10%413%28%34%10%
450
21st to endDay
9%315%35%30%8%
495
November1st to 10thDay
11%5%18%33%28%6%
455
11th to 20thDay
12%323%34%22%5%
460
21st to endDay
7%323%39%25%3
460
December1st to 10thDay
11%321%37%26%3
422
11th to 20thDay
9%5%21%39%23%3
270
21st to endDay
9%6%22%41%21%2
297
January1st to 10thNight
10%5%24%36%23%2
760
11th to 20thNight
11%6%25%36%21%2
727
21st to endNight
9%6%31%39%14%1
792
February1st to 10thNight
11%6%22%39%22%1
720
11th to 20thNight
7%6%25%39%22%1
703
21st to endNight
9%321%42%24%1
592
March1st to 10thNight
5%432%39%19%2
720
11th to 20thNight
7%324%40%25%2
720
21st to endNight
6%322%46%22%1
792
April1st to 10thNight
5%319%46%25%2
720
11th to 20thNight
6%5%21%42%25%2
711
21st to endNight
7%219%45%26%1
720
May1st to 10thNight
5%213%43%34%3
720
11th to 20thNight
10%212%38%33%5%
701
21st to endNight
8%29%23%45%13%
584
June1st to 10thNight
14%26%20%42%16%
540
11th to 20thNight
7%15%12%44%30%
540
21st to endNight
7%15%8%39%40%
540
July1st to 10thNight
6%138%41%42%
525
11th to 20thNight
6%26%41%45%
522
21st to endNight
5%129%40%44%
591
August1st to 10thNight
7%16%8%39%39%
563
11th to 20thNight
4137%45%40%
710
21st to endNight
9%16%14%38%32%
792
September1st to 10thNight
10%15%10%38%36%
720
11th to 20thNight
9%15%12%41%32%
720
21st to endNight
13%17%15%37%26%
720
October1st to 10thNight
12%27%27%39%13%
720
11th to 20thNight
11%210%28%38%11%
720
21st to endNight
14%212%33%32%7%
792
November1st to 10thNight
11%421%29%30%4
740
11th to 20thNight
11%223%29%32%3
760
21st to endNight
10%422%38%24%2
760
December1st to 10thNight
7%417%38%29%4
760
11th to 20thNight
13%6%19%34%26%4
760
21st to endNight
9%7%21%32%28%3
836
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