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Lexington
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lexington clear sky chart from 2005-11-06 to 2024-01-16.

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
42%
23715
20%
74269
14%
23662
49%
23662
23%
48938

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
19%
760
15%
2459
7%
757
29%
757
14%
1789
January11th to 20thNight
18%
741
15%
2406
8%
741
26%
741
12%
1825
January21st to endNight
20%
792
16%
2574
8%
792
30%
792
16%
1806
February1st to 10thNight
20%
720
13%
2204
6%
720
28%
720
15%
1651
February11th to 20thNight
17%
703
16%
2099
7%
700
26%
700
16%
1509
February21st to endNight
15%
592
15%
1776
6%
592
24%
592
13%
1341
March1st to 10thNight
25%
720
20%
2142
10%
720
33%
720
20%
1450
March11th to 20thNight
25%
720
17%
1980
7%
720
33%
720
20%
1402
March21st to endNight
31%
792
15%
2178
8%
792
36%
792
21%
1549
April1st to 10thNight
38%
604
22%
1864
14%
604
48%
604
26%
1157
April11th to 20thNight
36%
533
23%
1748
16%
533
47%
533
25%
1090
April21st to endNight
37%
540
19%
1620
10%
540
45%
540
24%
1094
May1st to 10thNight
35%
540
15%
1620
9%
540
41%
540
20%
1135
May11th to 20thNight
47%
531
15%
1593
11%
531
50%
531
22%
1089
May21st to endNight
62%
583
18%
1745
14%
582
64%
582
29%
1096
June1st to 10thNight
63%
540
19%
1620
15%
540
66%
540
37%
924
June11th to 20thNight
67%
540
19%
1612
16%
540
70%
540
36%
943
June21st to endNight
63%
540
21%
1440
15%
540
66%
540
36%
892
July1st to 10thNight
62%
525
16%
1451
14%
525
63%
525
30%
943
July11th to 20thNight
72%
522
19%
1566
16%
522
74%
522
36%
902
July21st to endNight
70%
591
21%
1672
19%
558
72%
558
33%
1017
August1st to 10thNight
75%
537
22%
1600
20%
534
75%
534
35%
961
August11th to 20thNight
71%
534
22%
1615
20%
534
73%
534
33%
985
August21st to endNight
74%
594
24%
1980
27%
594
74%
594
35%
1081
September1st to 10thNight
65%
643
23%
1903
20%
643
68%
643
32%
1154
September11th to 20thNight
64%
720
30%
1980
23%
720
68%
720
37%
1181
September21st to endNight
57%
720
29%
1980
21%
720
64%
720
35%
1208
October1st to 10thNight
60%
720
29%
1980
23%
720
65%
720
40%
1139
October11th to 20thNight
44%
720
26%
2114
20%
720
52%
720
30%
1311
October21st to endNight
36%
792
26%
2481
18%
792
47%
792
24%
1597
November1st to 10thNight
47%
740
27%
2406
24%
740
55%
740
31%
1386
November11th to 20thNight
34%
760
26%
2470
17%
760
46%
760
25%
1529
November21st to endNight
36%
760
22%
2470
16%
760
44%
760
22%
1623
December1st to 10thNight
26%
760
16%
2470
7%
760
36%
760
17%
1735
December11th to 20thNight
27%
759
19%
2965
11%
759
37%
759
15%
1999
December21st to endNight
23%
827
9%
4486
7%
817
33%
817
7%
3445

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
14%8%36%6%35%5%5%7%37%
75195
Night
14%8%36%5%3445%7%39%
74596
TransparencyDay
45%6%11%22%14%2
74917
Night
44%6%10%22%16%3
74394
SeeingDay
18%10%24%23%16%8%
13899
Night
18%8%25%29%17%2
23726

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
19%10%48%6%445%46%31%
1706
11th to 20thDay
21%12%6%11%6%24445%25%
1665
21st to endDay
16%11%6%8%7%35%5%5%6%30%
1782
February1st to 10thDay
19%11%6%10%5%25%446%28%
1754
11th to 20thDay
20%10%47%6%35%45%5%31%
1748
21st to endDay
20%11%48%5%4445%5%29%
1480
March1st to 10thDay
20%8%36%43345%6%37%
1818
11th to 20thDay
20%9%37%5%35%5%5%6%32%
1980
21st to endDay
20%9%37%6%35%45%6%31%
2178
April1st to 10thDay
13%7%36%6%345%5%7%41%
2110
11th to 20thDay
16%9%35%5%4445%6%39%
2160
21st to endDay
17%7%36%6%35%5%5%8%35%
2340
May1st to 10thDay
19%7%36%6%3446%7%35%
2340
11th to 20thDay
17%8%36%6%35%45%6%36%
2301
21st to endDay
8%6%36%7%46%6%7%11%37%
2531
June1st to 10thDay
11%5%36%6%46%6%5%7%43%
2340
11th to 20thDay
7%5%25%6%46%7%7%9%43%
2340
21st to endDay
8%5%35%5%46%6%7%10%40%
2517
July1st to 10thDay
12%7%36%5%46%6%7%9%35%
2458
11th to 20thDay
9%5%25%6%38%6%7%9%38%
2340
21st to endDay
11%6%25%6%46%7%6%9%38%
2547
August1st to 10thDay
11%6%26%436%6%6%9%42%
2327
11th to 20thDay
9%6%27%6%46%6%8%11%34%
2282
21st to endDay
9%5%26%6%45%6%6%9%42%
2376
September1st to 10thDay
14%5%246%36%6%6%7%40%
2039
11th to 20thDay
11%5%35%4345%7%8%45%
1980
21st to endDay
14%5%25%5%2345%6%49%
1980
October1st to 10thDay
10%5%2443445%6%52%
1980
11th to 20thDay
13%7%25%5%24446%48%
1845
21st to endDay
19%7%35%4235%46%43%
1872
November1st to 10thDay
11%6%24424336%54%
1672
11th to 20thDay
16%8%45%5%23447%43%
1710
21st to endDay
17%9%45%5%33446%39%
1710
December1st to 10thDay
21%13%46%5%35%34430%
1710
11th to 20thDay
15%13%48%6%44445%32%
2153
21st to endDay
18%16%5%8%6%36%5%5%6%22%
3124
January1st to 10thNight
16%11%6%8%8%35%445%30%
2459
11th to 20thNight
21%13%6%8%6%3444426%
2406
21st to endNight
17%10%5%8%6%35%45%5%34%
2574
February1st to 10thNight
21%11%5%8%5%34446%28%
2204
11th to 20thNight
21%9%38%6%3435%6%32%
2098
21st to endNight
23%12%47%6%3445%428%
1776
March1st to 10thNight
17%8%47%5%34445%40%
2142
11th to 20thNight
19%8%37%5%34446%36%
1980
21st to endNight
16%9%47%6%3445%7%35%
2178
April1st to 10thNight
12%5%35%5%36%5%6%7%44%
1864
11th to 20thNight
14%8%35%6%33447%42%
1748
21st to endNight
16%6%36%5%35%45%7%39%
1620
May1st to 10thNight
16%7%36%7%45%6%5%7%34%
1620
11th to 20thNight
16%6%36%6%45%6%6%8%36%
1592
21st to endNight
7%5%26%6%45%6%8%12%39%
1744
June1st to 10thNight
8%4245%345%8%11%47%
1620
11th to 20thNight
6%4246%25%6%7%10%48%
1612
21st to endNight
7%3245%35%7%7%13%43%
1440
July1st to 10thNight
8%5%36%7%35%46%9%44%
1494
11th to 20thNight
5%4245%46%5%7%11%48%
1620
21st to endNight
9%425%445%5%7%9%45%
1771
August1st to 10thNight
7%424435%5%7%10%48%
1611
11th to 20thNight
6%6%246%45%6%6%11%44%
1615
21st to endNight
7%4145%245%5%9%53%
1980
September1st to 10thNight
12%5%245%3445%8%48%
1903
11th to 20thNight
9%5%245%345%5%7%52%
1980
21st to endNight
11%5%25%435%35%6%52%
1980
October1st to 10thNight
10%42342445%7%55%
1980
11th to 20thNight
14%6%25%433447%47%
2114
21st to endNight
18%7%25%434445%43%
2481
November1st to 10thNight
12%5%45%424445%52%
2406
11th to 20thNight
15%7%45%334447%44%
2470
21st to endNight
16%8%46%5%34446%40%
2470
December1st to 10thNight
21%11%46%434446%33%
2470
11th to 20thNight
18%10%47%5%3435%6%35%
3042
21st to endNight
18%14%5%8%8%5%6%5%5%6%20%
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
55%49%20%11%1
1707
11th to 20thDay
61%49%17%8%1
1665
21st to endDay
55%49%22%8%2
1782
February1st to 10thDay
59%47%21%7%2
1754
11th to 20thDay
56%47%20%11%3
1758
21st to endDay
56%48%19%10%3
1480
March1st to 10thDay
49%310%22%15%2
1818
11th to 20thDay
54%49%18%12%2
1980
21st to endDay
53%5%10%21%9%2
2178
April1st to 10thDay
42%5%11%25%13%3
2110
11th to 20thDay
45%49%22%16%4
2160
21st to endDay
47%6%11%23%11%2
2340
May1st to 10thDay
47%6%12%24%10%1
2340
11th to 20thDay
48%6%12%21%12%1
2305
21st to endDay
40%8%17%22%12%1
2531
June1st to 10thDay
40%7%9%28%15%1
2340
11th to 20thDay
35%8%14%24%17%2
2340
21st to endDay
36%9%14%21%16%4
2517
July1st to 10thDay
42%8%13%19%16%2
2392
11th to 20thDay
39%9%14%21%14%3
2271
21st to endDay
39%8%14%25%12%2
2405
August1st to 10thDay
36%8%15%26%13%1
2314
11th to 20thDay
41%8%13%23%14%1
2282
21st to endDay
36%7%12%24%16%4
2376
September1st to 10thDay
41%7%13%19%16%5%
2039
11th to 20thDay
35%6%10%24%22%3
1980
21st to endDay
36%48%26%23%3
1980
October1st to 10thDay
32%5%9%24%26%3
1980
11th to 20thDay
37%48%25%22%4
1845
21st to endDay
44%48%25%16%3
1872
November1st to 10thDay
33%38%27%24%4
1672
11th to 20thDay
43%38%23%19%4
1710
21st to endDay
47%38%22%18%1
1710
December1st to 10thDay
58%39%20%9%1
1710
11th to 20thDay
54%5%9%17%14%1
2150
21st to endDay
62%5%9%17%6%1
3124
January1st to 10thNight
57%47%18%12%2
2459
11th to 20thNight
61%48%16%9%1
2406
21st to endNight
53%49%22%10%2
2574
February1st to 10thNight
59%310%19%8%1
2204
11th to 20thNight
54%47%21%11%2
2099
21st to endNight
59%5%9%13%11%3
1776
March1st to 10thNight
48%46%20%19%3
2142
11th to 20thNight
49%6%10%21%13%2
1980
21st to endNight
49%5%11%23%10%2
2178
April1st to 10thNight
38%6%10%24%19%3
1864
11th to 20thNight
41%5%9%20%19%7%
1748
21st to endNight
45%6%11%22%13%2
1620
May1st to 10thNight
47%8%9%22%10%3
1620
11th to 20thNight
45%7%13%20%13%2
1593
21st to endNight
35%9%16%23%15%3
1745
June1st to 10thNight
30%6%17%27%16%4
1620
11th to 20thNight
29%8%17%24%19%3
1612
21st to endNight
31%8%17%23%14%6%
1440
July1st to 10thNight
37%8%13%23%16%4
1451
11th to 20thNight
29%8%16%24%19%4
1566
21st to endNight
33%7%14%29%16%2
1672
August1st to 10thNight
30%9%16%26%17%2
1600
11th to 20thNight
33%8%15%27%15%2
1615
21st to endNight
27%8%14%27%20%4
1980
September1st to 10thNight
34%7%12%23%18%6%
1903
11th to 20thNight
32%5%10%26%24%3
1980
21st to endNight
34%5%7%24%26%4
1980
October1st to 10thNight
29%5%11%25%25%5%
1980
11th to 20thNight
38%5%7%25%22%4
2114
21st to endNight
43%45%24%20%4
2481
November1st to 10thNight
35%47%26%23%4
2406
11th to 20thNight
41%47%20%22%6%
2470
21st to endNight
46%48%24%16%2
2470
December1st to 10thNight
53%410%20%12%1
2470
11th to 20thNight
50%48%22%14%2
3044
21st to endNight
63%7%8%14%8%
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
26%17%34%16%7%1
270
11th to 20thDay
28%22%29%17%4
255
21st to endDay
22%21%40%14%3
264
February1st to 10thDay
25%22%38%11%4
240
11th to 20thDay
33%20%33%13%2
240
21st to endDay
32%16%39%10%3
198
March1st to 10thDay
26%21%38%12%3
258
11th to 20thDay
24%18%35%17%5%1
420
21st to endDay
28%14%31%20%6%1
462
April1st to 10thDay
17%16%29%23%12%2
420
11th to 20thDay
21%16%27%21%10%4
412
21st to endDay
22%13%30%22%10%4
420
May1st to 10thDay
22%11%31%18%13%5%
423
11th to 20thDay
17%8%26%26%16%7%
447
21st to endDay
13%421%28%20%13%
485
June1st to 10thDay
14%418%24%29%11%
450
11th to 20thDay
9%322%28%25%12%
450
21st to endDay
9%422%31%21%13%
627
July1st to 10thDay
14%312%25%21%24%
562
11th to 20thDay
9%316%24%29%19%
444
21st to endDay
12%312%28%27%17%
488
August1st to 10thDay
14%216%24%27%18%
446
11th to 20thDay
13%313%31%26%13%
439
21st to endDay
10%212%30%29%17%
495
September1st to 10thDay
14%312%27%27%17%
450
11th to 20thDay
13%113%25%29%18%
450
21st to endDay
16%9%17%22%26%10%
450
October1st to 10thDay
12%7%18%31%23%10%
450
11th to 20thDay
15%11%28%29%12%4
450
21st to endDay
20%11%33%26%10%1
387
November1st to 10thDay
16%9%32%26%13%4
270
11th to 20thDay
23%17%26%24%8%2
270
21st to endDay
23%11%35%23%7%1
270
December1st to 10thDay
24%19%30%23%41
270
11th to 20thDay
22%14%38%18%8%
270
21st to endDay
27%19%34%16%3
297
January1st to 10thNight
24%15%36%20%5%
760
11th to 20thNight
29%17%31%20%3
741
21st to endNight
24%13%38%23%2
792
February1st to 10thNight
27%13%34%24%2
720
11th to 20thNight
28%15%37%20%1
703
21st to endNight
29%14%37%18%2
592
March1st to 10thNight
22%14%34%25%5%
720
11th to 20thNight
24%13%34%22%8%1
720
21st to endNight
22%11%31%28%8%
792
April1st to 10thNight
16%11%32%32%9%
604
11th to 20thNight
17%10%31%28%13%1
533
21st to endNight
18%6%34%30%10%1
540
May1st to 10thNight
21%5%32%25%15%2
540
11th to 20thNight
18%5%21%35%19%2
531
21st to endNight
9%315%36%31%5%
584
June1st to 10thNight
8%118%43%25%4
540
11th to 20thNight
8%215%41%29%5%
540
21st to endNight
8%218%39%29%4
540
July1st to 10thNight
10%211%32%33%11%
525
11th to 20thNight
6%211%36%40%6%
522
21st to endNight
13%27%36%36%6%
591
August1st to 10thNight
10%17%36%41%5%
537
11th to 20thNight
8%39%38%35%7%
534
21st to endNight
8%19%34%42%6%
594
September1st to 10thNight
14%210%31%37%7%
643
11th to 20thNight
13%213%28%38%6%
720
21st to endNight
12%320%35%27%3
720
October1st to 10thNight
11%319%34%28%4
720
11th to 20thNight
17%8%27%31%16%2
720
21st to endNight
21%8%31%26%12%2
792
November1st to 10thNight
15%7%26%32%18%2
740
11th to 20thNight
19%11%32%28%9%1
760
21st to endNight
21%12%27%29%10%1
760
December1st to 10thNight
26%12%31%26%5%
760
11th to 20thNight
26%9%33%26%6%
760
21st to endNight
27%15%29%25%4
836
Page generated at 2024-01-13 01:38:13. Version ac07

Copyright 2024 Attilla Danko


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