Lenox
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lenox clear sky chart from 2005-11-05 to 2017-09-19.

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%
15976
21%
46944
11%
15929
47%
15929
30%
28840

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
29%
900
20%
2367
8%
895
39%
895
29%
1518
January16th to endNight
24%
960
21%
2496
7%
960
34%
960
28%
1645
February1st to 15thNight
25%
880
13%
2288
4%
876
30%
876
23%
1628
February16th to endNight
26%
708
23%
1970
7%
708
38%
708
29%
1249
March1st to 15thNight
33%
540
22%
1980
13%
540
46%
540
25%
1139
March16th to endNight
23%
576
14%
2112
9%
576
32%
576
16%
1443
April1st to 15thNight
30%
539
19%
1836
13%
539
42%
539
26%
1092
April16th to endNight
30%
540
20%
1685
12%
540
42%
540
22%
1128
May1st to 15thNight
37%
539
17%
1620
11%
539
45%
539
24%
1072
May16th to endNight
42%
563
18%
1544
9%
561
50%
561
31%
989
June1st to 15thNight
54%
540
19%
1440
9%
540
58%
540
41%
841
June16th to endNight
57%
540
21%
1440
10%
540
61%
540
48%
803
July1st to 15thNight
68%
510
18%
1408
12%
510
70%
510
45%
774
July16th to endNight
73%
564
22%
1594
19%
531
75%
531
46%
829
August1st to 15thNight
73%
539
22%
1610
22%
536
77%
536
43%
857
August16th to endNight
65%
573
25%
1797
26%
573
70%
573
37%
998
September1st to 15thNight
60%
540
25%
1829
24%
540
67%
540
34%
1005
September16th to endNight
54%
507
28%
1860
22%
507
64%
507
36%
940
October1st to 15thNight
40%
660
26%
1980
16%
660
48%
660
33%
1159
October16th to endNight
34%
704
24%
2112
11%
704
45%
704
32%
1226
November1st to 15thNight
37%
794
27%
2248
13%
794
49%
794
37%
1276
November16th to endNight
28%
900
20%
2520
8%
900
38%
900
29%
1577
December1st to 15thNight
25%
900
16%
2520
5%
900
33%
900
23%
1724
December16th to endNight
23%
960
18%
2688
6%
960
34%
960
20%
1928

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
9%6%219%423346%35%
47871
Night
8%5%219%423345%40%
47133
Cloud CoverDay
12%7%35%5%3445%7%41%
47869
Night
10%6%25%42445%7%46%
47133
TransparencyDay
41%5%14%24%13%1
47563
Night
37%413%26%15%2
46944
SeeingDay
13%8%27%30%16%3
5995
Night
13%8%32%31%11%
15977

By Month

Percentage Cloud Cover SW (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
7%7%223%5%33335%32%
1570
16th to endDay
11%9%324%5%2333425%
1728
February1st to 15thDay
9%8%224%6%33346%27%
1575
16th to endDay
10%9%222%5%23445%30%
1511
March1st to 15thDay
9%8%323%423346%31%
1980
16th to endDay
13%9%322%423345%27%
2112
April1st to 15thDay
14%7%222%32232433%
2112
16th to endDay
17%8%221%5%24335%23%
2274
May1st to 15thDay
11%6%221%5%24345%31%
2331
16th to endDay
12%7%222%423345%30%
2570
June1st to 15thDay
9%6%121%423346%36%
2520
16th to endDay
42120%43445%8%39%
2520
July1st to 15thDay
6%3120%4245%6%7%37%
2466
16th to endDay
43120%323448%42%
2466
August1st to 15thDay
6%3114%4335%6%9%40%
2340
16th to endDay
9%5%213%42346%6%42%
2403
September1st to 15thDay
9%4211%423345%48%
2130
16th to endDay
7%3113%32335%7%47%
1832
October1st to 15thDay
12%6%213%412235%47%
1650
16th to endDay
11%6%214%323435%43%
1760
November1st to 15thDay
6%4117%322335%47%
1605
16th to endDay
12%6%320%422246%34%
1440
December1st to 15thDay
10%8%423%5%23445%26%
1440
16th to endDay
12%9%325%5%23225%26%
1536
January1st to 15thNight
6%5%122%5%23346%37%
2367
16th to endNight
8%8%323%323345%34%
2496
February1st to 15thNight
9%9%222%5%23346%30%
2278
16th to endNight
7%5%321%423336%37%
1970
March1st to 15thNight
10%6%121%31323440%
1980
16th to endNight
13%6%223%5%14245%30%
2112
April1st to 15thNight
10%5%121%423336%38%
1836
16th to endNight
12%9%323%5%2332331%
1685
May1st to 15thNight
10%5%220%5%32345%35%
1619
16th to endNight
8%4121%422446%37%
1542
June1st to 15thNight
7%3120%412337%43%
1440
16th to endNight
22119%22236%8%47%
1440
July1st to 15thNight
3219%323448%47%
1492
16th to endNight
22120%31335%6%47%
1702
August1st to 15thNight
42113%22345%9%50%
1620
16th to endNight
7%3112%32335%5%52%
1797
September1st to 15thNight
8%3112%323346%49%
1829
16th to endNight
8%3111%322346%52%
1860
October1st to 15thNight
12%4213%31223448%
1980
16th to endNight
10%4114%312235%49%
2112
November1st to 15thNight
7%3117%222245%48%
2248
16th to endNight
10%6%220%21234440%
2520
December1st to 15thNight
11%8%223%422335%30%
2520
16th to endNight
11%8%224%5%2333429%
2688

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
9%9%37%6%34437%39%
1570
16th to endDay
13%11%5%8%6%24436%32%
1728
February1st to 15thDay
12%9%49%6%4435%7%32%
1575
16th to endDay
12%10%37%6%3445%6%36%
1511
March1st to 15thDay
11%10%47%5%34347%36%
1980
16th to endDay
17%11%5%6%5%2435%6%31%
2110
April1st to 15thDay
16%8%35%5%24435%39%
2112
16th to endDay
21%8%35%5%34446%31%
2274
May1st to 15thDay
15%7%45%6%35%45%6%35%
2331
16th to endDay
15%7%26%5%25%45%6%37%
2570
June1st to 15thDay
10%7%25%43445%7%43%
2520
16th to endDay
6%3245%35%5%6%9%45%
2520
July1st to 15thDay
7%414425%6%7%9%45%
2466
16th to endDay
5%3144345%5%10%50%
2466
August1st to 15thDay
7%415%5%446%8%10%42%
2340
16th to endDay
10%5%35%42346%6%45%
2403
September1st to 15thDay
11%42342345%6%51%
2130
16th to endDay
9%315%33446%8%51%
1832
October1st to 15thDay
13%6%24412335%51%
1650
16th to endDay
13%7%25%323435%46%
1760
November1st to 15thDay
8%5%23423437%53%
1605
16th to endDay
15%8%45%42325%7%39%
1440
December1st to 15thDay
12%10%5%8%7%2445%7%32%
1440
16th to endDay
14%11%410%7%24437%28%
1536
January1st to 15thNight
8%6%26%6%25%45%7%43%
2367
16th to endNight
9%8%36%425%447%42%
2496
February1st to 15thNight
11%10%47%6%24347%34%
2278
16th to endNight
10%6%35%434447%45%
1970
March1st to 15thNight
11%7%25%323445%48%
1980
16th to endNight
17%9%37%6%2435%6%33%
2112
April1st to 15thNight
13%5%25%42335%7%45%
1836
16th to endNight
15%9%36%5%2342440%
1685
May1st to 15thNight
13%5%345%3445%6%41%
1619
16th to endNight
10%5%245%24448%46%
1542
June1st to 15thNight
7%42342345%9%52%
1440
16th to endNight
43123245%7%10%54%
1440
July1st to 15thNight
431342445%11%54%
1492
16th to endNight
321342446%8%56%
1702
August1st to 15thNight
5%214225%46%10%54%
1620
16th to endNight
9%31442435%6%54%
1797
September1st to 15thNight
10%42432435%6%53%
1829
16th to endNight
10%31332345%6%55%
1860
October1st to 15thNight
13%5%24312335%52%
1980
16th to endNight
12%5%25%422235%53%
2112
November1st to 15thNight
9%42322335%7%54%
2248
16th to endNight
12%7%35%313446%47%
2520
December1st to 15thNight
13%9%37%5%33446%37%
2520
16th to endNight
14%10%48%6%2435%5%33%
2688

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
45%315%20%13%
1571
16th to endDay
53%216%17%9%
1728
February1st to 15thDay
50%5%13%22%7%
1576
16th to endDay
46%5%14%20%11%1
1511
March1st to 15thDay
47%414%22%9%1
1980
16th to endDay
53%5%14%19%6%
2112
April1st to 15thDay
47%411%25%10%1
2112
16th to endDay
52%413%19%9%
2274
May1st to 15thDay
49%5%12%19%11%
2331
16th to endDay
45%6%13%23%9%1
2574
June1st to 15thDay
39%5%15%24%13%2
2520
16th to endDay
32%6%16%28%15%1
2520
July1st to 15thDay
31%7%17%27%12%3
2321
16th to endDay
27%6%16%29%17%2
2311
August1st to 15thDay
33%7%16%26%14%
2326
16th to endDay
37%6%10%23%16%4
2403
September1st to 15thDay
32%413%27%18%3
2130
16th to endDay
30%5%12%32%18%
1832
October1st to 15thDay
36%210%28%19%2
1650
16th to endDay
39%310%27%15%2
1760
November1st to 15thDay
31%213%29%20%2
1605
16th to endDay
45%214%27%10%
1440
December1st to 15thDay
50%416%19%7%
1440
16th to endDay
55%312%17%9%
1536
January1st to 15thNight
38%415%25%15%
2367
16th to endNight
41%316%24%12%
2496
February1st to 15thNight
49%313%22%9%1
2288
16th to endNight
38%413%23%17%2
1970
March1st to 15thNight
37%312%27%16%2
1980
16th to endNight
51%5%12%21%8%1
2112
April1st to 15thNight
38%312%27%16%1
1836
16th to endNight
47%312%22%12%2
1685
May1st to 15thNight
42%6%12%22%14%1
1620
16th to endNight
36%6%15%26%12%2
1544
June1st to 15thNight
28%5%18%28%16%3
1440
16th to endNight
22%6%17%29%21%3
1440
July1st to 15thNight
25%419%32%13%4
1408
16th to endNight
22%5%15%36%18%2
1594
August1st to 15thNight
24%5%18%34%14%2
1610
16th to endNight
29%5%12%25%19%8%
1797
September1st to 15thNight
31%410%25%23%4
1829
16th to endNight
28%311%34%19%2
1860
October1st to 15thNight
35%39%25%23%3
1980
16th to endNight
34%212%26%20%3
2112
November1st to 15thNight
29%314%24%23%4
2248
16th to endNight
37%313%28%14%1
2520
December1st to 15thNight
47%316%23%9%
2520
16th to endNight
51%412%19%10%1
2688

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
20%11%41%24%21
90
16th to endDay
25%14%33%23%3
96
February1st to 15thDay
11%18%44%20%5%
90
16th to endDay
16%18%41%13%9%
81
March1st to 15thDay
15%17%48%16%1
90
16th to endDay
27%14%37%17%3
96
April1st to 15thDay
21%11%33%22%11%
231
16th to endDay
27%12%31%19%8%
384
May1st to 15thDay
17%14%32%25%8%1
468
16th to endDay
18%9%31%27%11%1
517
June1st to 15thDay
11%7%25%32%19%3
495
16th to endDay
5%6%34%31%18%4
495
July1st to 15thDay
8%320%38%22%6%
475
16th to endDay
3216%45%28%3
515
August1st to 15thDay
8%117%41%26%5%
493
16th to endDay
12%318%35%21%7%
443
September1st to 15thDay
10%323%30%24%6%
285
16th to endDay
7%433%33%19%3
99
October1st to 15thDay
10%7%30%35%8%7%
90
16th to endDay
10%12%38%31%7%
96
November1st to 15thDay
5%7%34%32%13%6%
90
16th to endDay
36%10%40%12%1
90
December1st to 15thDay
14%24%34%21%23
90
16th to endDay
29%21%37%11%
96
January1st to 15thNight
11%13%41%26%7%
900
16th to endNight
15%12%41%25%5%
960
February1st to 15thNight
16%13%37%27%5%
880
16th to endNight
13%12%41%25%5%1
708
March1st to 15thNight
16%10%34%29%8%
540
16th to endNight
20%10%40%21%6%
576
April1st to 15thNight
14%13%37%30%4
539
16th to endNight
20%10%35%26%6%
540
May1st to 15thNight
15%8%33%32%9%
540
16th to endNight
12%6%31%34%14%
563
June1st to 15thNight
9%426%42%16%
540
16th to endNight
5%231%44%16%
540
July1st to 15thNight
6%18%45%27%1
510
16th to endNight
413%51%29%
564
August1st to 15thNight
6%13%51%25%2
539
16th to endNight
9%215%40%28%3
573
September1st to 15thNight
11%320%34%25%3
540
16th to endNight
12%328%33%21%1
507
October1st to 15thNight
15%7%31%30%12%1
660
16th to endNight
16%9%34%29%8%
704
November1st to 15thNight
11%12%34%31%9%
794
16th to endNight
18%12%39%21%7%
900
December1st to 15thNight
19%12%38%23%5%
900
16th to endNight
19%11%37%26%5%
960
Page generated at 2017-09-20 03:49:46. Version ac04

Copyright 2017 A. Danko


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