Lafayette
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lafayette clear sky chart from 2005-11-05 to 2017-09-17.

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
58%
15309
23%
46826
19%
15264
62%
15264
31%
28161

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
39%
900
24%
2327
10%
895
47%
895
31%
1508
January16th to endNight
38%
960
25%
2496
11%
960
45%
960
30%
1639
February1st to 15thNight
39%
738
26%
2146
13%
735
48%
735
29%
1339
February16th to endNight
36%
577
22%
1839
13%
577
43%
577
25%
1145
March1st to 15thNight
42%
540
24%
1980
18%
540
51%
540
24%
1183
March16th to endNight
49%
576
22%
2112
18%
576
57%
576
31%
1142
April1st to 15thNight
47%
539
25%
1800
18%
539
58%
539
30%
1052
April16th to endNight
53%
540
25%
1800
23%
540
60%
540
32%
1025
May1st to 15thNight
59%
539
20%
1799
21%
539
64%
539
32%
1036
May16th to endNight
73%
562
22%
1840
25%
561
76%
561
38%
988
June1st to 15thNight
83%
540
16%
1620
19%
540
84%
540
37%
947
June16th to endNight
76%
540
15%
1620
17%
540
77%
540
27%
1042
July1st to 15thNight
83%
510
15%
1530
19%
510
83%
510
33%
934
July16th to endNight
80%
564
12%
1597
15%
531
81%
531
28%
1023
August1st to 15thNight
85%
539
15%
1788
19%
536
86%
536
33%
1018
August16th to endNight
75%
573
13%
1910
16%
573
75%
573
22%
1286
September1st to 15thNight
75%
540
20%
1800
24%
540
75%
540
29%
1108
September16th to endNight
71%
565
27%
1811
27%
565
72%
565
30%
1080
October1st to 15thNight
74%
660
32%
1980
28%
660
76%
660
47%
1000
October16th to endNight
64%
704
33%
2112
28%
704
68%
704
42%
1122
November1st to 15thNight
58%
700
32%
2100
26%
700
63%
700
36%
1196
November16th to endNight
54%
720
34%
2160
25%
720
63%
720
39%
1203
December1st to 15thNight
46%
723
26%
2163
19%
723
53%
723
26%
1380
December16th to endNight
35%
960
19%
2496
10%
960
39%
960
23%
1765

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
11%6%36%6%46%5%6%7%36%
47934
Night
9%42442446%8%47%
47026
TransparencyDay
43%8%11%16%15%5%
47637
Night
33%7%13%19%17%8%
46828
SeeingDay
11%312%21%28%21%
5391
Night
11%418%31%27%6%
15311

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
16%6%35%424445%42%
1611
16th to endDay
19%6%35%43433442%
1728
February1st to 15thDay
14%8%35%42445%6%40%
1714
16th to endDay
17%8%35%425%446%38%
1644
March1st to 15thDay
17%7%35%423446%38%
1980
16th to endDay
10%6%36%43345%8%41%
2110
April1st to 15thDay
11%5%34436%5%7%8%39%
2145
16th to endDay
10%5%35%5%5%6%6%6%9%36%
2160
May1st to 15thDay
8%5%37%5%45%5%6%8%38%
2151
16th to endDay
8%435%6%47%6%8%9%36%
2271
June1st to 15thDay
5%5%38%9%6%7%7%7%7%30%
2340
16th to endDay
6%5%37%10%6%10%9%9%9%21%
2340
July1st to 15thDay
9%6%36%7%5%9%8%9%10%23%
2340
16th to endDay
9%6%38%8%5%8%8%8%8%23%
2460
August1st to 15thDay
7%5%26%8%48%9%10%11%25%
2160
16th to endDay
11%6%37%8%5%8%7%6%8%24%
2292
September1st to 15thDay
11%5%26%6%37%5%7%7%35%
2160
16th to endDay
10%7%27%5%46%5%6%5%37%
1838
October1st to 15thDay
7%3145%34447%52%
1650
16th to endDay
9%314423445%56%
1760
November1st to 15thDay
8%5%245%2345%7%48%
1758
16th to endDay
11%5%24423345%53%
1800
December1st to 15thDay
16%7%244245%6%7%37%
1794
16th to endDay
16%7%47%5%3346%6%32%
1728
January1st to 15thNight
14%425%32445%6%45%
2327
16th to endNight
15%6%24423445%44%
2496
February1st to 15thNight
13%6%2442435%6%45%
2137
16th to endNight
17%6%25%31335%5%45%
1839
March1st to 15thNight
14%6%25%423447%43%
1980
16th to endNight
9%5%1442345%8%51%
2112
April1st to 15thNight
11%42442345%9%47%
1800
16th to endNight
6%5%144345%5%7%50%
1800
May1st to 15thNight
8%4245%245%7%10%45%
1799
16th to endNight
6%31333445%10%53%
1839
June1st to 15thNight
2312435%6%6%10%51%
1620
16th to endNight
5%3245%47%5%8%11%39%
1620
July1st to 15thNight
4215%426%6%8%11%46%
1620
16th to endNight
33345%36%6%9%13%40%
1705
August1st to 15thNight
42133346%8%12%48%
1800
16th to endNight
6%325%7%46%6%10%11%34%
1910
September1st to 15thNight
8%424435%48%9%43%
1800
16th to endNight
7%5%25%4245%6%8%46%
1811
October1st to 15thNight
4312323347%61%
1980
16th to endNight
8%323223246%59%
2112
November1st to 15thNight
9%424423346%54%
2100
16th to endNight
10%414313245%57%
2160
December1st to 15thNight
13%6%34425%45%6%43%
2163
16th to endNight
18%8%35%5%33346%37%
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
43%36%17%19%9%
1612
16th to endDay
46%35%14%18%11%
1728
February1st to 15thDay
43%47%15%20%8%
1716
16th to endDay
45%46%18%19%6%
1644
March1st to 15thDay
45%5%8%17%17%5%
1980
16th to endDay
39%5%9%19%21%4
2112
April1st to 15thDay
39%6%10%18%17%8%
2145
16th to endDay
41%7%11%18%16%4
2160
May1st to 15thDay
41%7%11%19%13%6%
2151
16th to endDay
38%9%13%22%14%1
2275
June1st to 15thDay
46%10%11%17%13%
2340
16th to endDay
51%13%14%14%6%
2340
July1st to 15thDay
48%13%17%16%4
2201
16th to endDay
51%14%17%13%3
2305
August1st to 15thDay
44%15%21%14%4
2148
16th to endDay
51%13%15%10%6%1
2292
September1st to 15thDay
44%10%14%16%10%3
2160
16th to endDay
44%6%9%15%15%6%
1838
October1st to 15thDay
30%6%8%18%21%14%
1650
16th to endDay
29%45%13%29%17%
1760
November1st to 15thDay
34%48%18%25%8%
1758
16th to endDay
32%37%13%28%13%
1800
December1st to 15thDay
43%6%8%19%14%7%
1794
16th to endDay
50%47%17%15%4
1728
January1st to 15thNight
38%47%14%22%12%
2327
16th to endNight
40%37%16%19%12%
2496
February1st to 15thNight
39%36%18%19%11%
2146
16th to endNight
40%47%17%18%11%
1839
March1st to 15thNight
39%5%11%17%17%8%
1980
16th to endNight
30%5%14%19%21%7%
2112
April1st to 15thNight
33%6%11%19%17%11%
1800
16th to endNight
31%6%12%22%18%8%
1800
May1st to 15thNight
31%7%15%21%15%9%
1800
16th to endNight
25%7%18%27%19%1
1841
June1st to 15thNight
25%10%18%26%17%1
1620
16th to endNight
35%10%21%22%9%
1620
July1st to 15thNight
27%12%29%22%7%
1530
16th to endNight
28%17%30%19%4
1597
August1st to 15thNight
24%13%28%25%7%
1788
16th to endNight
37%14%24%14%6%2
1910
September1st to 15thNight
34%8%18%22%10%5%
1800
16th to endNight
32%8%13%18%18%7%
1811
October1st to 15thNight
21%410%21%25%16%
1980
16th to endNight
26%36%15%25%23%
2112
November1st to 15thNight
31%48%19%25%10%
2100
16th to endNight
29%35%18%26%16%
2160
December1st to 15thNight
40%5%9%21%17%6%
2163
16th to endNight
48%46%17%14%8%
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
25%8%30%22%11%2
90
16th to endDay
16%10%47%17%7%
96
February1st to 15thDay
8%12%27%36%14%
90
16th to endDay
12%11%39%23%13%
81
March1st to 15thDay
26%10%40%14%6%2
90
16th to endDay
12%14%17%23%25%6%
96
April1st to 15thDay
11%7%25%33%20%1
264
16th to endDay
16%317%34%23%4
270
May1st to 15thDay
12%316%33%28%5%
288
16th to endDay
11%215%26%30%14%
358
June1st to 15thDay
8%18%27%33%20%
495
16th to endDay
9%15%21%33%29%
495
July1st to 15thDay
7%317%35%35%
475
16th to endDay
8%312%36%38%
509
August1st to 15thDay
8%35%30%50%
313
16th to endDay
12%6%11%30%38%
332
September1st to 15thDay
9%6%19%33%29%
315
16th to endDay
8%27%14%44%22%
182
October1st to 15thDay
1217%28%33%16%
90
16th to endDay
18%13%26%27%14%
96
November1st to 15thDay
21%326%25%17%5%
90
16th to endDay
18%6%26%28%10%8%
90
December1st to 15thDay
28%7%22%23%14%3
90
16th to endDay
25%11%29%23%10%
96
January1st to 15thNight
16%7%31%32%10%
900
16th to endNight
18%9%30%31%9%
960
February1st to 15thNight
16%8%30%36%7%
738
16th to endNight
21%11%27%33%5%
577
March1st to 15thNight
17%6%27%38%10%
540
16th to endNight
11%428%37%17%
576
April1st to 15thNight
12%6%28%35%15%
539
16th to endNight
7%427%41%17%
540
May1st to 15thNight
10%219%49%17%1
540
16th to endNight
7%111%38%36%4
563
June1st to 15thNight
3334%49%8%
540
16th to endNight
5%1421%49%18%
540
July1st to 15thNight
3212%56%22%
510
16th to endNight
31110%56%26%
564
August1st to 15thNight
410%56%27%
539
16th to endNight
7%1314%49%23%
573
September1st to 15thNight
10%1320%47%17%
540
16th to endNight
9%6%26%49%7%
565
October1st to 15thNight
4210%35%40%5%
660
16th to endNight
9%417%35%28%4
704
November1st to 15thNight
11%220%40%22%2
700
16th to endNight
11%5%24%40%17%1
720
December1st to 15thNight
16%8%23%33%17%
723
16th to endNight
23%8%27%27%12%
960
Page generated at 2017-09-18 07:38:25. Version ac04

Copyright 2017 A. Danko


Lafayette Clear Sky Chart | Charts Home