Lexington Trails
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lexington Trails clear sky chart from 2005-11-05 to 2017-10-06.

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
40%
15539
20%
46848
13%
15495
47%
15495
24%
30540

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
15%
799
14%
2405
6%
794
24%
794
12%
1839
January16th to endNight
18%
768
15%
2496
7%
768
28%
768
13%
1801
February1st to 15thNight
18%
703
13%
2149
5%
701
27%
701
15%
1554
February16th to endNight
16%
631
14%
1893
6%
631
23%
631
15%
1371
March1st to 15thNight
22%
720
17%
2096
9%
720
28%
720
17%
1451
March16th to endNight
28%
768
16%
2112
7%
768
35%
768
22%
1472
April1st to 15thNight
31%
569
19%
1827
12%
569
41%
569
24%
1165
April16th to endNight
35%
540
21%
1658
11%
540
44%
540
24%
1091
May1st to 15thNight
37%
540
15%
1620
9%
540
42%
540
21%
1132
May16th to endNight
55%
562
19%
1684
14%
561
59%
561
32%
1026
June1st to 15thNight
63%
540
20%
1581
16%
540
68%
540
42%
891
June16th to endNight
61%
540
20%
1440
13%
540
66%
540
39%
865
July1st to 15thNight
57%
510
17%
1372
13%
510
60%
510
33%
885
July16th to endNight
72%
564
20%
1595
18%
531
75%
531
39%
907
August1st to 15thNight
70%
539
24%
1609
21%
536
72%
536
37%
939
August16th to endNight
74%
573
26%
1857
26%
573
76%
573
41%
954
September1st to 15thNight
64%
660
27%
1920
23%
660
67%
660
37%
1115
September16th to endNight
58%
717
31%
1980
24%
717
62%
717
37%
1162
October1st to 15thNight
55%
684
31%
1908
24%
684
62%
684
37%
1106
October16th to endNight
37%
704
24%
2194
17%
704
48%
704
25%
1369
November1st to 15thNight
42%
700
28%
2276
22%
700
53%
700
30%
1297
November16th to endNight
31%
720
19%
2340
14%
720
40%
720
19%
1556
December1st to 15thNight
22%
720
13%
2340
8%
720
28%
720
13%
1711
December16th to endNight
18%
768
14%
2496
5%
768
28%
768
12%
1881

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
15%7%36%5%3445%7%37%
48316
Night
14%7%35%42445%7%39%
47031
Cloud CoverDay
15%7%36%5%3445%7%37%
48325
Night
14%7%35%42445%7%39%
47036
TransparencyDay
46%310%22%14%2
48017
Night
44%311%22%15%2
46848
SeeingDay
17%9%24%23%15%8%
5694
Night
18%10%24%27%16%2
15541

By Month

Percentage Cloud Cover NE (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%11%5%10%5%24235%27%
1507
16th to endDay
15%12%6%8%6%24345%30%
1728
February1st to 15thDay
16%12%5%8%5%33336%31%
1711
16th to endDay
16%12%5%7%6%25%436%30%
1580
March1st to 15thDay
23%9%36%42433433%
1853
16th to endDay
19%10%36%5%24446%32%
2112
April1st to 15thDay
19%7%25%424446%39%
2132
16th to endDay
16%6%25%5%3445%6%38%
2301
May1st to 15thDay
22%8%25%5%3445%6%31%
2331
16th to endDay
11%6%26%6%45%6%7%8%35%
2431
June1st to 15thDay
10%5%246%35%5%5%8%41%
2375
16th to endDay
8%435%6%46%5%6%8%40%
2520
July1st to 15thDay
14%6%36%5%35%5%7%8%33%
2503
16th to endDay
9%325%5%47%7%7%9%37%
2465
August1st to 15thDay
7%425%6%36%6%7%9%40%
2340
16th to endDay
8%5%25%5%45%5%6%9%41%
2344
September1st to 15thDay
13%425%5%35%446%44%
2028
16th to endDay
13%5%25%5%24346%48%
1980
October1st to 15thDay
11%5%15%5%2445%5%48%
1848
16th to endDay
20%6%14422337%43%
1677
November1st to 15thDay
10%7%34323445%50%
1582
16th to endDay
18%9%35%324345%39%
1620
December1st to 15thDay
25%11%46%5%2344428%
1620
16th to endDay
20%15%5%8%423336%28%
1728
January1st to 15thNight
18%11%411%7%23435%26%
2405
16th to endNight
18%12%47%6%33345%30%
2496
February1st to 15thNight
20%10%5%8%423345%31%
2147
16th to endNight
18%12%47%5%23446%29%
1893
March1st to 15thNight
18%9%47%6%23446%33%
2083
16th to endNight
16%9%26%5%34448%35%
2112
April1st to 15thNight
15%6%3443445%6%40%
1827
16th to endNight
15%7%25%5%34346%40%
1658
May1st to 15thNight
16%7%35%435%5%6%7%33%
1620
16th to endNight
9%4144346%7%11%40%
1682
June1st to 15thNight
6%31442435%10%52%
1581
16th to endNight
6%3233246%7%11%47%
1440
July1st to 15thNight
10%5%15%7%2345%8%45%
1453
16th to endNight
6%3245%25%45%10%48%
1703
August1st to 15thNight
5%4145%3446%9%49%
1620
16th to endNight
5%31432446%11%53%
1857
September1st to 15thNight
12%31332345%8%50%
1920
16th to endNight
11%424323447%52%
1980
October1st to 15thNight
9%41433445%7%51%
1908
16th to endNight
16%7%25%433345%43%
2194
November1st to 15thNight
13%5%24323447%49%
2276
16th to endNight
19%10%24324446%37%
2340
December1st to 15thNight
22%12%46%5%24335%28%
2340
16th to endNight
22%14%47%424345%25%
2496

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%11%5%10%5%2323427%
1507
16th to endDay
15%13%5%8%6%24335%30%
1728
February1st to 15thDay
15%12%5%8%5%33336%32%
1711
16th to endDay
15%12%47%6%26%436%30%
1580
March1st to 15thDay
23%9%35%5%2433433%
1863
16th to endDay
18%10%35%6%24446%32%
2111
April1st to 15thDay
19%7%25%424446%39%
2132
16th to endDay
16%6%25%5%34446%39%
2301
May1st to 15thDay
22%7%26%435%45%6%31%
2331
16th to endDay
10%6%26%6%35%6%7%8%35%
2431
June1st to 15thDay
10%5%25%6%35%5%5%8%41%
2375
16th to endDay
8%435%6%46%5%6%9%40%
2520
July1st to 15thDay
14%6%26%5%35%5%7%8%33%
2503
16th to endDay
9%3245%47%6%7%9%37%
2465
August1st to 15thDay
7%426%5%36%6%7%9%40%
2340
16th to endDay
8%5%25%5%35%5%6%9%41%
2344
September1st to 15thDay
13%425%5%35%446%43%
2028
16th to endDay
13%5%25%5%23345%48%
1980
October1st to 15thDay
11%5%145%2445%5%48%
1848
16th to endDay
20%6%14423236%43%
1677
November1st to 15thDay
10%7%34323435%50%
1582
16th to endDay
18%9%35%423345%39%
1620
December1st to 15thDay
25%11%45%5%2343427%
1620
16th to endDay
20%14%5%7%423335%28%
1728
January1st to 15thNight
18%11%411%7%23435%26%
2405
16th to endNight
18%12%47%5%33345%30%
2496
February1st to 15thNight
19%11%5%8%423345%31%
2140
16th to endNight
18%13%47%6%23446%29%
1893
March1st to 15thNight
18%8%47%5%23445%33%
2096
16th to endNight
17%8%36%5%24448%35%
2112
April1st to 15thNight
14%6%4442445%7%40%
1827
16th to endNight
15%7%25%6%34346%40%
1658
May1st to 15thNight
16%7%36%5%35%5%6%7%33%
1619
16th to endNight
9%414425%6%7%11%40%
1682
June1st to 15thNight
5%32442435%10%51%
1581
16th to endNight
6%3133346%8%11%47%
1440
July1st to 15thNight
10%5%15%6%2335%7%45%
1453
16th to endNight
6%3245%25%46%9%48%
1703
August1st to 15thNight
6%3145%35%46%9%49%
1620
16th to endNight
5%2233245%6%11%52%
1857
September1st to 15thNight
12%3133225%5%8%50%
1920
16th to endNight
10%424323447%52%
1980
October1st to 15thNight
8%4133345%5%7%51%
1908
16th to endNight
16%7%25%433335%43%
2194
November1st to 15thNight
13%5%23323447%48%
2276
16th to endNight
19%10%24324446%37%
2340
December1st to 15thNight
22%12%5%6%5%24335%28%
2340
16th to endNight
22%14%47%5%23345%25%
2496

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
60%28%16%10%
1508
16th to endDay
56%210%23%6%
1728
February1st to 15thDay
55%29%22%9%
1713
16th to endDay
55%311%21%7%
1580
March1st to 15thDay
54%210%19%10%1
1863
16th to endDay
53%310%22%9%
2112
April1st to 15thDay
46%29%23%15%2
2132
16th to endDay
44%39%23%14%4
2301
May1st to 15thDay
52%412%18%10%1
2331
16th to endDay
44%5%14%20%13%1
2435
June1st to 15thDay
39%5%12%23%17%1
2375
16th to endDay
39%5%12%21%17%3
2520
July1st to 15thDay
46%5%10%17%16%3
2355
16th to endDay
38%6%14%23%14%2
2310
August1st to 15thDay
37%6%12%24%16%2
2327
16th to endDay
36%412%23%17%5%
2344
September1st to 15thDay
39%410%19%19%5%
2028
16th to endDay
38%38%23%24%1
1980
October1st to 15thDay
36%39%27%19%3
1848
16th to endDay
44%110%27%14%2
1677
November1st to 15thDay
36%37%26%20%5%
1582
16th to endDay
48%27%23%16%
1620
December1st to 15thDay
59%210%18%8%1
1620
16th to endDay
60%210%17%8%
1728
January1st to 15thNight
62%26%17%10%
2405
16th to endNight
56%210%20%7%1
2496
February1st to 15thNight
56%210%21%7%1
2149
16th to endNight
55%311%19%9%
1893
March1st to 15thNight
51%29%21%12%1
2096
16th to endNight
48%312%24%9%
2112
April1st to 15thNight
42%310%21%19%2
1827
16th to endNight
45%39%20%14%7%
1658
May1st to 15thNight
49%5%12%21%9%2
1620
16th to endNight
33%7%16%21%16%3
1684
June1st to 15thNight
27%415%30%17%4
1581
16th to endNight
28%7%17%22%20%3
1440
July1st to 15thNight
38%410%22%17%5%
1372
16th to endNight
29%5%15%29%17%2
1595
August1st to 15thNight
31%5%15%26%18%3
1609
16th to endNight
25%415%29%20%5%
1857
September1st to 15thNight
31%412%23%22%6%
1920
16th to endNight
32%37%24%28%2
1980
October1st to 15thNight
31%38%29%22%5%
1908
16th to endNight
43%17%27%17%2
2194
November1st to 15thNight
35%28%22%26%5%
2276
16th to endNight
48%210%21%14%1
2340
December1st to 15thNight
59%210%17%8%
2340
16th to endNight
61%210%16%7%
2496

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%21%33%8%22
90
16th to endDay
22%37%33%42
96
February1st to 15thDay
21%46%24%6%1
90
16th to endDay
20%16%53%9%
81
March1st to 15thDay
26%21%33%16%1
153
16th to endDay
23%18%31%16%8%1
288
April1st to 15thDay
22%15%28%20%10%1
270
16th to endDay
18%12%31%18%13%5%
270
May1st to 15thDay
27%9%31%14%9%6%
288
16th to endDay
17%8%24%25%12%11%
331
June1st to 15thDay
10%5%18%38%18%8%
350
16th to endDay
11%8%27%26%17%7%
495
July1st to 15thDay
19%5%21%26%17%10%
459
16th to endDay
11%14%30%21%22%
326
August1st to 15thDay
12%114%28%23%20%
313
16th to endDay
11%212%31%27%15%
332
September1st to 15thDay
14%413%28%22%15%
315
16th to endDay
15%316%19%29%14%
314
October1st to 15thDay
11%7%25%27%18%8%
278
16th to endDay
17%9%34%24%11%1
189
November1st to 15thDay
13%13%30%24%11%7%
90
16th to endDay
26%20%32%18%2
90
December1st to 15thDay
27%20%30%15%5%1
90
16th to endDay
29%29%34%6%1
96
January1st to 15thNight
24%21%33%17%4
799
16th to endNight
25%20%30%21%1
768
February1st to 15thNight
26%16%33%22%1
704
16th to endNight
25%17%35%20%1
631
March1st to 15thNight
25%16%29%23%4
720
16th to endNight
22%13%30%24%8%
768
April1st to 15thNight
17%14%32%26%7%
569
16th to endNight
17%9%32%28%10%1
540
May1st to 15thNight
20%8%27%26%15%
540
16th to endNight
12%221%33%22%6%
563
June1st to 15thNight
7%221%40%25%2
540
16th to endNight
6%322%37%26%3
540
July1st to 15thNight
13%115%34%29%5%
510
16th to endNight
8%8%36%38%7%
564
August1st to 15thNight
8%8%35%39%6%
539
16th to endNight
6%11%33%41%6%
573
September1st to 15thNight
13%312%31%32%6%
660
16th to endNight
13%5%15%25%34%4
717
October1st to 15thNight
11%7%21%30%22%4
684
16th to endNight
19%10%28%27%12%1
704
November1st to 15thNight
16%11%27%23%18%2
700
16th to endNight
25%15%23%25%9%
720
December1st to 15thNight
31%14%25%20%7%1
720
16th to endNight
32%14%28%19%3
768
Page generated at 2017-10-07 14:07:55. Version ac04

Copyright 2017 A. Danko


Lexington Trails Clear Sky Chart | Charts Home