Evansville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Evansville clear sky chart from 2005-11-05 to 2018-03-21.

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
39%
16520
22%
49159
14%
16476
47%
16476
24%
31106

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
23%
975
18%
2716
9%
970
32%
970
19%
1883
January16th to endNight
23%
1011
19%
2772
7%
1011
32%
1011
19%
1935
February1st to 15thNight
19%
764
17%
2292
6%
761
28%
761
16%
1600
February16th to endNight
21%
683
17%
2049
6%
683
31%
683
17%
1405
March1st to 15thNight
24%
780
17%
2340
7%
780
32%
780
18%
1573
March16th to endNight
32%
675
16%
2090
9%
675
40%
675
17%
1440
April1st to 15thNight
35%
539
22%
1797
14%
539
48%
539
24%
1073
April16th to endNight
35%
540
21%
1776
13%
540
46%
540
22%
1100
May1st to 15thNight
38%
539
18%
1619
9%
539
46%
539
22%
1069
May16th to endNight
47%
561
19%
1637
10%
561
55%
561
24%
1036
June1st to 15thNight
53%
540
22%
1440
13%
540
60%
540
32%
855
June16th to endNight
60%
540
24%
1440
16%
540
65%
540
38%
829
July1st to 15thNight
60%
510
20%
1360
15%
510
63%
510
35%
835
July16th to endNight
64%
564
24%
1449
18%
531
73%
531
39%
831
August1st to 15thNight
69%
539
24%
1732
24%
536
72%
536
36%
925
August16th to endNight
70%
573
27%
1910
30%
573
74%
573
35%
1023
September1st to 15thNight
63%
573
27%
1833
27%
573
66%
573
33%
1045
September16th to endNight
57%
717
30%
1980
21%
717
63%
717
34%
1172
October1st to 15thNight
50%
720
30%
2007
22%
720
57%
720
33%
1194
October16th to endNight
39%
768
27%
2418
19%
768
50%
768
28%
1458
November1st to 15thNight
39%
760
28%
2471
21%
760
50%
760
28%
1424
November16th to endNight
31%
780
26%
2535
15%
780
46%
780
23%
1515
December1st to 15thNight
29%
829
16%
2584
10%
829
37%
829
17%
1769
December16th to endNight
18%
1040
16%
2912
5%
1040
28%
1040
16%
2117

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
13%6%25%5%3445%7%41%
49694
Night
14%6%25%42345%7%44%
49338
TransparencyDay
41%5%12%23%15%2
49376
Night
40%411%23%17%3
49161
SeeingDay
15%12%21%22%19%9%
6349
Night
14%18%21%26%15%2
16523

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
21%7%37%5%23445%33%
1552
16th to endDay
13%8%46%5%33446%39%
1797
February1st to 15thDay
17%9%46%423347%36%
1900
16th to endDay
15%8%47%5%46%5%5%5%31%
1710
March1st to 15thDay
20%8%35%424335%38%
1950
16th to endDay
18%9%36%5%345%5%7%32%
2270
April1st to 15thDay
13%5%35%43445%8%41%
2151
16th to endDay
15%5%35%5%33447%40%
2184
May1st to 15thDay
18%6%25%5%2446%8%34%
2331
16th to endDay
9%5%26%5%46%5%6%8%37%
2474
June1st to 15thDay
7%314435%46%8%47%
2520
16th to endDay
6%2245%35%5%7%10%45%
2520
July1st to 15thDay
11%425%435%5%7%10%39%
2520
16th to endDay
5%2145%46%6%7%11%42%
2619
August1st to 15thDay
6%4245%36%5%6%10%44%
2214
16th to endDay
7%324435%47%9%46%
2292
September1st to 15thDay
10%425%6%345%6%7%43%
2115
16th to endDay
11%424433346%51%
1980
October1st to 15thDay
12%414423346%50%
1950
16th to endDay
14%5%24423345%49%
1806
November1st to 15thDay
12%5%24423347%48%
1717
16th to endDay
19%7%24323335%45%
1755
December1st to 15thDay
21%8%36%32424436%
1703
16th to endDay
20%11%26%413345%35%
1664
January1st to 15thNight
19%8%36%433345%37%
2716
16th to endNight
15%9%36%5%24446%36%
2772
February1st to 15thNight
18%9%46%5%23446%35%
2283
16th to endNight
16%8%46%43445%6%36%
2049
March1st to 15thNight
17%7%35%5%24435%39%
2340
16th to endNight
18%6%36%4345%5%6%35%
2090
April1st to 15thNight
14%6%23323446%47%
1797
16th to endNight
17%5%35%422347%42%
1776
May1st to 15thNight
14%6%26%5%2345%7%39%
1619
16th to endNight
6%326%5%46%5%6%9%42%
1636
June1st to 15thNight
7%424435%46%9%49%
1440
16th to endNight
5%2144245%8%9%52%
1440
July1st to 15thNight
7%42441445%9%49%
1440
16th to endNight
5%213425%46%10%51%
1547
August1st to 15thNight
5%31432346%8%54%
1743
16th to endNight
441342446%10%52%
1910
September1st to 15thNight
10%3143235%5%7%51%
1833
16th to endNight
10%424423347%51%
1980
October1st to 15thNight
10%425%423335%54%
2007
16th to endNight
16%5%2332343449%
2418
November1st to 15thNight
13%424422446%50%
2471
16th to endNight
17%6%23423345%48%
2535
December1st to 15thNight
21%7%35%423445%36%
2584
16th to endNight
21%10%35%424345%33%
2912

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
52%410%19%11%
1553
16th to endDay
45%312%28%8%1
1797
February1st to 15thDay
49%411%23%10%1
1902
16th to endDay
52%5%11%19%10%
1710
March1st to 15thDay
49%39%22%13%1
1950
16th to endDay
50%5%13%23%6%1
2271
April1st to 15thDay
40%5%12%24%17%
2151
16th to endDay
43%412%25%12%2
2184
May1st to 15thDay
47%6%13%21%10%
2331
16th to endDay
41%7%14%19%13%2
2478
June1st to 15thDay
32%6%12%27%19%2
2520
16th to endDay
32%8%13%21%19%4
2520
July1st to 15thDay
38%6%13%21%14%4
2371
16th to endDay
29%8%18%25%14%2
2455
August1st to 15thDay
33%6%14%24%18%2
2201
16th to endDay
32%6%14%22%19%5%
2292
September1st to 15thDay
36%6%9%22%19%4
2115
16th to endDay
34%47%24%25%3
1980
October1st to 15thDay
34%49%25%21%4
1950
16th to endDay
37%38%28%20%2
1806
November1st to 15thDay
36%39%24%17%7%
1717
16th to endDay
43%37%26%16%2
1755
December1st to 15thDay
51%312%20%11%
1703
16th to endDay
52%312%21%9%
1664
January1st to 15thNight
49%39%21%15%1
2716
16th to endNight
47%412%23%11%1
2772
February1st to 15thNight
50%310%23%9%1
2292
16th to endNight
48%412%21%11%1
2049
March1st to 15thNight
47%49%21%13%3
2340
16th to endNight
47%6%14%20%10%1
2090
April1st to 15thNight
37%411%24%18%4
1797
16th to endNight
40%49%25%16%4
1776
May1st to 15thNight
43%5%12%23%14%
1620
16th to endNight
35%8%13%20%17%4
1638
June1st to 15thNight
30%5%13%26%21%3
1440
16th to endNight
24%7%15%22%23%5%
1440
July1st to 15thNight
31%6%12%27%17%5%
1360
16th to endNight
26%5%15%30%18%3
1449
August1st to 15thNight
26%5%16%24%23%4
1732
16th to endNight
26%6%12%27%21%5%
1910
September1st to 15thNight
31%5%8%26%21%6%
1833
16th to endNight
32%38%22%24%6%
1980
October1st to 15thNight
33%38%22%25%6%
2007
16th to endNight
38%36%28%18%5%
2418
November1st to 15thNight
34%39%21%23%7%
2471
16th to endNight
39%29%25%20%2
2535
December1st to 15thNight
48%410%21%12%1
2584
16th to endNight
53%312%19%9%1
2912

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
32%8%37%11%8%2
135
16th to endDay
15%20%37%21%4
144
February1st to 15thDay
25%12%42%16%3
135
16th to endDay
30%14%31%19%4
120
March1st to 15thDay
25%11%45%15%1
135
16th to endDay
20%19%29%22%8%
282
April1st to 15thDay
15%18%29%22%13%
270
16th to endDay
18%15%24%21%15%4
270
May1st to 15thDay
20%18%24%20%10%5%
288
16th to endDay
15%13%23%21%15%9%
374
June1st to 15thDay
9%15%14%22%25%12%
495
16th to endDay
7%14%22%28%17%8%
495
July1st to 15thDay
13%9%14%25%23%13%
475
16th to endDay
5%12%6%22%31%20%
479
August1st to 15thDay
13%7%7%19%29%23%
313
16th to endDay
10%5%8%21%38%15%
332
September1st to 15thDay
11%7%11%19%28%20%
315
16th to endDay
12%7%11%20%28%19%
314
October1st to 15thDay
15%6%18%25%24%8%
285
16th to endDay
15%431%29%16%2
144
November1st to 15thDay
17%6%24%27%16%8%
135
16th to endDay
25%5%32%25%10%
135
December1st to 15thDay
14%17%34%22%7%3
135
16th to endDay
32%15%41%7%2
144
January1st to 15thNight
18%24%29%21%5%
975
16th to endNight
17%25%29%24%2
1011
February1st to 15thNight
21%25%28%21%2
764
16th to endNight
19%24%31%22%2
683
March1st to 15thNight
20%22%28%25%3
780
16th to endNight
18%22%22%28%8%
675
April1st to 15thNight
14%22%25%27%8%1
539
16th to endNight
17%20%22%26%12%
540
May1st to 15thNight
14%20%21%31%10%1
540
16th to endNight
7%18%17%29%22%3
563
June1st to 15thNight
9%17%13%31%25%2
540
16th to endNight
417%11%37%25%2
540
July1st to 15thNight
9%11%10%29%35%3
510
16th to endNight
5%16%6%26%36%9%
564
August1st to 15thNight
7%9%5%29%39%8%
539
16th to endNight
6%8%6%31%39%6%
573
September1st to 15thNight
11%9%9%26%35%7%
573
16th to endNight
11%10%11%25%33%7%
717
October1st to 15thNight
12%11%17%27%24%5%
720
16th to endNight
16%13%27%28%13%1
768
November1st to 15thNight
11%18%25%28%15%1
760
16th to endNight
18%21%25%23%9%
780
December1st to 15thNight
22%20%23%25%6%1
829
16th to endNight
22%24%30%18%3
1040
Page generated at 2018-03-22 10:34:22. Version ac04

Copyright 2018 A. Danko


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