Litchfield High School
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Litchfield High School clear sky chart from 2005-11-06 to 2024-01-14.

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
36%
24870
17%
74415
9%
24814
43%
24814
24%
49325

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
28%
950
13%
2778
5%
946
36%
946
19%
1961
January11th to 20thNight
28%
920
12%
2499
6%
920
32%
920
16%
1902
January21st to endNight
23%
990
13%
2574
4%
990
30%
990
17%
1956
February1st to 10thNight
28%
900
14%
2340
3%
900
35%
900
23%
1657
February11th to 20thNight
27%
879
17%
2274
5%
875
35%
875
26%
1538
February21st to endNight
29%
737
17%
1921
5%
737
38%
737
23%
1375
March1st to 10thNight
30%
540
14%
1980
10%
540
37%
540
19%
1302
March11th to 20thNight
31%
540
19%
1980
11%
540
44%
540
20%
1245
March21st to endNight
33%
594
14%
2178
11%
594
40%
594
16%
1486
April1st to 10thNight
29%
540
17%
1827
10%
540
41%
540
21%
1182
April11th to 20thNight
31%
533
21%
1689
16%
533
41%
533
20%
1145
April21st to endNight
30%
540
17%
1620
12%
540
39%
540
20%
1126
May1st to 10thNight
35%
540
15%
1584
9%
540
40%
540
25%
1046
May11th to 20thNight
37%
531
18%
1417
7%
531
43%
531
28%
942
May21st to endNight
45%
584
15%
1552
6%
582
49%
582
32%
995
June1st to 10thNight
51%
540
16%
1427
6%
540
54%
540
39%
868
June11th to 20thNight
46%
540
17%
1260
6%
540
50%
540
41%
807
June21st to endNight
58%
540
18%
1260
7%
540
61%
540
46%
781
July1st to 10thNight
62%
525
19%
1225
8%
525
65%
525
51%
720
July11th to 20thNight
62%
522
22%
1337
9%
522
65%
522
50%
739
July21st to endNight
65%
591
22%
1580
14%
558
67%
558
48%
843
August1st to 10thNight
63%
537
21%
1601
16%
534
66%
534
35%
927
August11th to 20thNight
61%
534
22%
1600
20%
534
67%
534
37%
921
August21st to endNight
58%
594
25%
1837
23%
594
66%
594
42%
965
September1st to 10thNight
57%
540
23%
1800
22%
540
65%
540
36%
945
September11th to 20thNight
49%
540
26%
1898
21%
540
59%
540
32%
1037
September21st to endNight
40%
562
25%
2002
16%
562
54%
562
30%
1105
October1st to 10thNight
36%
720
22%
2160
13%
720
44%
720
30%
1338
October11th to 20thNight
30%
720
23%
2160
10%
720
40%
720
25%
1373
October21st to endNight
29%
792
20%
2376
9%
792
39%
792
21%
1578
November1st to 10thNight
34%
920
20%
2550
10%
920
43%
920
27%
1648
November11th to 20thNight
26%
950
17%
2660
7%
950
35%
950
19%
1907
November21st to endNight
27%
950
17%
2660
7%
950
35%
950
23%
1803
December1st to 10thNight
27%
950
12%
2660
4%
950
34%
950
19%
1933
December11th to 20thNight
22%
949
12%
3218
3%
949
30%
949
13%
2378
December21st to endNight
19%
1036
7%
4931
4%
1026
27%
1026
7%
3851

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%8%37%6%35%5%6%7%38%
75024
Night
12%8%47%6%3445%7%41%
74736
TransparencyDay
44%6%14%24%11%1
74722
Night
43%6%13%24%12%2
74559
SeeingDay
16%9%30%28%14%3
14844
Night
15%9%33%32%11%1
24880

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
8%11%5%10%8%47%6%6%8%27%
1377
11th to 20thDay
10%12%5%11%8%5%5%5%5%6%26%
1537
21st to endDay
8%12%7%10%10%6%8%6%5%8%20%
1782
February1st to 10thDay
8%11%48%8%5%6%6%6%8%31%
1620
11th to 20thDay
8%9%5%9%8%45%6%6%7%32%
1574
21st to endDay
10%11%47%9%46%5%6%7%30%
1350
March1st to 10thDay
13%12%6%8%6%35%45%7%31%
1980
11th to 20thDay
14%8%48%6%35%5%5%6%37%
1980
21st to endDay
18%9%48%7%3445%7%29%
2178
April1st to 10thDay
17%10%37%5%245%6%6%36%
2132
11th to 20thDay
19%11%47%6%345%46%32%
2217
21st to endDay
23%10%36%5%34446%32%
2340
May1st to 10thDay
18%7%45%6%36%5%5%6%35%
2376
11th to 20thDay
17%6%37%6%345%5%7%38%
2479
21st to endDay
15%6%35%5%35%5%7%8%38%
2725
June1st to 10thDay
11%4345%346%7%8%45%
2528
11th to 20thDay
12%7%35%5%35%6%7%7%39%
2700
21st to endDay
9%5%245%36%5%7%10%45%
2700
July1st to 10thDay
6%3235%25%6%6%10%52%
2700
11th to 20thDay
8%42443445%8%54%
2574
21st to endDay
5%325%5%35%5%6%10%52%
2640
August1st to 10thDay
9%5%25%6%45%5%6%9%42%
2328
11th to 20thDay
13%6%245%3446%8%45%
2301
21st to endDay
9%42442345%8%54%
2518
September1st to 10thDay
11%42443445%8%50%
2160
11th to 20thDay
12%426%5%35%5%6%8%45%
2060
21st to endDay
16%6%25%433448%45%
1940
October1st to 10thDay
18%7%25%5%3345%6%41%
1800
11th to 20thDay
16%8%35%5%24448%40%
1800
21st to endDay
17%10%46%5%3345%7%37%
1980
November1st to 10thDay
13%9%46%6%345%5%6%38%
1525
11th to 20thDay
9%11%6%12%8%35%446%31%
1520
21st to endDay
13%10%36%7%45%47%9%33%
1520
December1st to 10thDay
9%11%5%10%7%5%6%6%6%6%27%
1520
11th to 20thDay
10%13%7%9%7%45%45%6%30%
1918
21st to endDay
22%13%5%15%6%33346%20%
2645
January1st to 10thNight
7%8%6%11%8%46%46%8%32%
2778
11th to 20thNight
9%13%6%10%8%45%5%6%6%27%
2499
21st to endNight
11%13%5%10%8%445%6%7%26%
2574
February1st to 10thNight
6%11%5%7%8%46%5%5%6%36%
2340
11th to 20thNight
6%8%47%6%45%5%7%8%40%
2273
21st to endNight
12%10%46%6%46%5%6%7%36%
1921
March1st to 10thNight
12%9%48%6%35%45%8%37%
1980
11th to 20thNight
13%9%46%5%24445%42%
1980
21st to endNight
18%9%46%5%345%46%34%
2178
April1st to 10thNight
14%9%36%5%3445%7%39%
1827
11th to 20thNight
19%11%46%42345%5%36%
1689
21st to endNight
20%9%35%6%3445%6%37%
1620
May1st to 10thNight
16%7%35%5%345%5%6%42%
1584
11th to 20thNight
14%6%35%425%46%8%43%
1416
21st to endNight
13%5%26%43445%8%46%
1551
June1st to 10thNight
11%3244345%6%8%50%
1427
11th to 20thNight
8%5%25%435%47%9%49%
1260
21st to endNight
8%3133345%5%8%57%
1260
July1st to 10thNight
43143235%6%9%59%
1260
11th to 20thNight
432343345%9%61%
1381
21st to endNight
431342446%7%61%
1673
August1st to 10thNight
7%4245%35%47%8%51%
1611
11th to 20thNight
9%425%5%2445%7%54%
1600
21st to endNight
7%323433346%61%
1837
September1st to 10thNight
8%32432446%8%56%
1800
11th to 20thNight
10%42442445%7%54%
1898
21st to endNight
11%5%2442345%6%54%
2002
October1st to 10thNight
16%6%24433447%48%
2160
11th to 20thNight
15%9%3442445%6%43%
2160
21st to endNight
17%11%36%423446%40%
2376
November1st to 10thNight
11%7%36%4445%5%7%44%
2550
11th to 20thNight
12%11%5%9%6%34445%36%
2660
21st to endNight
12%8%47%6%3445%7%40%
2660
December1st to 10thNight
9%10%6%9%8%445%5%7%33%
2660
11th to 20thNight
11%10%5%9%9%46%6%5%6%28%
3279
21st to endNight
21%13%5%11%8%34445%22%
5012

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
54%6%15%18%7%
1378
11th to 20thDay
59%5%12%16%7%1
1537
21st to endDay
61%7%12%14%7%
1782
February1st to 10thDay
50%6%13%22%8%1
1620
11th to 20thDay
52%5%14%20%8%1
1583
21st to endDay
53%6%9%21%11%1
1350
March1st to 10thDay
52%6%13%20%7%1
1980
11th to 20thDay
48%6%14%24%8%1
1980
21st to endDay
55%6%12%22%5%
2178
April1st to 10thDay
48%6%11%22%12%1
2132
11th to 20thDay
53%6%11%18%11%1
2217
21st to endDay
53%6%11%20%9%1
2340
May1st to 10thDay
49%7%12%21%10%1
2376
11th to 20thDay
45%6%12%24%12%
2483
21st to endDay
43%7%13%24%11%1
2725
June1st to 10thDay
34%8%16%29%12%1
2528
11th to 20thDay
41%8%14%22%14%1
2700
21st to endDay
32%9%19%28%11%2
2700
July1st to 10thDay
25%8%18%33%16%1
2626
11th to 20thDay
28%7%15%28%19%3
2496
21st to endDay
26%9%16%31%16%2
2493
August1st to 10thDay
36%9%15%26%10%3
2314
11th to 20thDay
36%8%16%29%11%1
2301
21st to endDay
28%5%16%33%16%2
2518
September1st to 10thDay
33%6%13%35%13%
2160
11th to 20thDay
36%7%17%30%9%
2060
21st to endDay
39%5%12%34%10%1
1940
October1st to 10thDay
43%5%12%27%13%1
1800
11th to 20thDay
43%6%13%24%13%2
1800
21st to endDay
48%414%24%10%1
1980
November1st to 10thDay
45%6%13%21%13%3
1525
11th to 20thDay
54%6%12%18%10%1
1520
21st to endDay
48%5%16%23%7%2
1520
December1st to 10thDay
55%8%14%16%7%
1520
11th to 20thDay
56%5%16%18%5%
1915
21st to endDay
67%410%14%5%
2645
January1st to 10thNight
50%6%12%22%10%1
2778
11th to 20thNight
56%7%13%17%8%1
2499
21st to endNight
57%413%17%8%1
2574
February1st to 10thNight
48%5%14%21%12%1
2340
11th to 20thNight
42%6%16%23%11%2
2274
21st to endNight
47%6%11%21%13%2
1921
March1st to 10thNight
47%6%15%24%8%
1980
11th to 20thNight
44%413%24%13%1
1980
21st to endNight
51%5%12%24%7%1
2178
April1st to 10thNight
44%5%12%26%12%1
1827
11th to 20thNight
49%47%22%15%2
1689
21st to endNight
48%6%9%21%14%2
1620
May1st to 10thNight
42%6%13%25%13%1
1584
11th to 20thNight
39%7%13%22%16%3
1417
21st to endNight
36%6%15%25%15%2
1552
June1st to 10thNight
30%7%16%31%15%2
1427
11th to 20thNight
31%6%16%27%17%3
1260
21st to endNight
25%8%16%30%18%3
1260
July1st to 10thNight
22%6%16%35%20%1
1225
11th to 20thNight
21%5%16%36%17%4
1337
21st to endNight
21%7%16%36%16%5%
1580
August1st to 10thNight
30%7%15%30%14%4
1601
11th to 20thNight
30%6%17%31%15%1
1600
21st to endNight
24%6%14%32%21%4
1837
September1st to 10thNight
26%6%15%34%18%1
1800
11th to 20thNight
30%6%14%32%17%
1898
21st to endNight
32%5%12%34%16%1
2002
October1st to 10thNight
37%5%9%31%16%2
2160
11th to 20thNight
41%5%11%26%15%2
2160
21st to endNight
45%5%12%25%12%1
2376
November1st to 10thNight
39%6%15%24%14%2
2550
11th to 20thNight
51%6%12%19%12%1
2660
21st to endNight
45%5%18%24%8%2
2660
December1st to 10thNight
52%6%15%20%7%
2660
11th to 20thNight
54%8%13%18%6%1
3281
21st to endNight
65%6%9%16%5%
5012

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
15%9%31%26%16%2
270
11th to 20thDay
17%11%33%34%41
249
21st to endDay
16%8%44%22%9%2
264
February1st to 10thDay
15%12%43%28%2
240
11th to 20thDay
17%17%33%26%7%1
240
21st to endDay
18%10%38%27%6%
198
March1st to 10thDay
20%11%40%23%5%1
240
11th to 20thDay
18%9%37%25%10%2
240
21st to endDay
24%14%24%25%11%2
264
April1st to 10thDay
24%15%31%23%6%
392
11th to 20thDay
26%13%24%24%11%2
495
21st to endDay
26%9%33%20%11%2
600
May1st to 10thDay
20%10%36%24%9%1
603
11th to 20thDay
20%9%29%25%13%3
625
21st to endDay
17%7%31%28%14%3
679
June1st to 10thDay
9%7%26%32%21%5%
630
11th to 20thDay
16%6%32%32%11%2
630
21st to endDay
11%5%32%30%16%5%
630
July1st to 10thDay
7%323%35%23%8%
621
11th to 20thDay
9%6%27%31%21%6%
618
21st to endDay
7%424%38%24%5%
684
August1st to 10thDay
12%320%35%27%4
626
11th to 20thDay
13%6%20%34%22%5%
615
21st to endDay
9%5%25%33%23%5%
637
September1st to 10thDay
13%8%28%32%15%4
450
11th to 20thDay
13%5%29%29%19%5%
350
21st to endDay
22%11%30%21%12%4
270
October1st to 10thDay
18%11%29%24%12%6%
270
11th to 20thDay
13%19%38%19%10%1
270
21st to endDay
25%12%39%16%8%
297
November1st to 10thDay
19%13%33%25%8%2
270
11th to 20thDay
13%15%45%22%4
270
21st to endDay
22%14%38%21%5%
270
December1st to 10thDay
12%11%40%27%9%1
270
11th to 20thDay
17%12%37%29%5%
270
21st to endDay
29%9%35%23%3
297
January1st to 10thNight
11%11%38%30%9%1
950
11th to 20thNight
15%10%35%32%7%1
920
21st to endNight
17%11%36%29%7%
990
February1st to 10thNight
12%11%38%30%8%1
900
11th to 20thNight
11%12%40%29%6%1
879
21st to endNight
16%11%34%29%9%1
737
March1st to 10thNight
16%9%38%25%11%1
540
11th to 20thNight
18%8%37%29%6%1
540
21st to endNight
22%9%30%28%10%2
594
April1st to 10thNight
18%9%38%27%7%
540
11th to 20thNight
22%12%28%28%9%1
533
21st to endNight
24%8%31%26%9%1
540
May1st to 10thNight
19%8%34%30%8%1
540
11th to 20thNight
17%8%34%29%10%1
531
21st to endNight
16%7%27%36%12%1
584
June1st to 10thNight
12%5%28%39%15%1
540
11th to 20thNight
9%436%41%11%
540
21st to endNight
9%425%45%17%1
540
July1st to 10thNight
5%225%41%26%2
525
11th to 20thNight
5%325%48%17%1
522
21st to endNight
6%123%48%20%2
591
August1st to 10thNight
9%317%48%22%2
537
11th to 20thNight
11%417%41%24%4
534
21st to endNight
8%426%38%23%2
594
September1st to 10thNight
9%5%26%40%18%2
540
11th to 20thNight
11%6%30%33%17%2
540
21st to endNight
12%10%33%31%13%2
562
October1st to 10thNight
19%6%34%28%12%1
720
11th to 20thNight
20%10%35%27%8%1
720
21st to endNight
23%11%31%27%7%
792
November1st to 10thNight
16%10%34%31%9%
920
11th to 20thNight
17%12%37%27%7%1
950
21st to endNight
17%13%36%27%7%
950
December1st to 10thNight
14%11%37%29%8%1
950
11th to 20thNight
20%8%38%26%7%1
950
21st to endNight
24%10%32%27%5%1
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