Fairfield Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fairfield Lake State Park 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
51%
15510
27%
46920
19%
15463
59%
15463
36%
26416

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
35%
898
27%
2327
11%
895
45%
895
33%
1451
January16th to endNight
35%
960
29%
2496
11%
960
45%
960
34%
1555
February1st to 15thNight
33%
779
26%
2179
10%
772
43%
772
30%
1337
February16th to endNight
27%
572
29%
1834
12%
572
43%
572
29%
1048
March1st to 15thNight
33%
540
27%
1980
16%
540
47%
540
24%
1170
March16th to endNight
34%
576
24%
2112
16%
576
46%
576
29%
1159
April1st to 15thNight
33%
539
25%
1953
15%
539
50%
539
31%
1031
April16th to endNight
36%
540
25%
1790
17%
540
51%
540
31%
1007
May1st to 15thNight
37%
539
22%
1620
15%
539
48%
539
30%
981
May16th to endNight
55%
562
26%
1685
23%
561
64%
561
42%
915
June1st to 15thNight
76%
540
24%
1620
26%
540
80%
540
52%
790
June16th to endNight
76%
540
24%
1620
28%
540
79%
540
45%
869
July1st to 15thNight
78%
510
23%
1530
27%
510
80%
510
46%
794
July16th to endNight
84%
564
23%
1594
28%
531
86%
531
47%
823
August1st to 15thNight
88%
539
31%
1610
36%
536
89%
536
54%
767
August16th to endNight
72%
573
24%
1894
28%
573
74%
573
33%
1086
September1st to 15thNight
73%
540
22%
1980
27%
540
74%
540
33%
1048
September16th to endNight
74%
504
33%
1857
35%
504
76%
504
39%
916
October1st to 15thNight
68%
588
34%
1908
30%
588
72%
588
43%
964
October16th to endNight
58%
704
37%
2112
23%
704
67%
704
47%
1067
November1st to 15thNight
51%
700
31%
2100
20%
700
59%
700
39%
1153
November16th to endNight
46%
843
32%
2283
18%
843
55%
843
37%
1365
December1st to 15thNight
40%
900
28%
2340
14%
900
48%
900
33%
1483
December16th to endNight
36%
960
24%
2496
11%
960
44%
960
29%
1637

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%5%2442445%7%46%
47880
Night
10%413323347%54%
47123
TransparencyDay
36%5%11%21%18%7%
47580
Night
30%411%22%21%10%
46928
SeeingDay
10%416%26%30%11%
5520
Night
13%5%24%33%20%2
15514

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
14%7%3332323450%
1611
16th to endDay
17%5%24222346%48%
1728
February1st to 15thDay
16%7%24312235%48%
1684
16th to endDay
17%5%14322245%48%
1638
March1st to 15thDay
21%6%24413345%42%
1980
16th to endDay
15%6%35%424335%45%
2110
April1st to 15thDay
11%6%25%5%3446%8%42%
1995
16th to endDay
12%5%25%4345%5%7%43%
2167
May1st to 15thDay
12%6%26%435%5%5%6%40%
2331
16th to endDay
10%435%6%36%5%7%9%38%
2430
June1st to 15thDay
5%3235%35%5%7%12%46%
2340
16th to endDay
6%224436%6%7%11%43%
2340
July1st to 15thDay
7%3245%35%5%6%10%43%
2340
16th to endDay
5%425%5%36%6%7%10%41%
2466
August1st to 15thDay
411332446%11%56%
2340
16th to endDay
7%425%7%45%5%7%8%39%
2302
September1st to 15thDay
10%5%244345%5%7%44%
1980
16th to endDay
7%32443445%7%52%
1848
October1st to 15thDay
10%314323347%54%
1710
16th to endDay
10%31221223465%
1760
November1st to 15thDay
11%5%245%24345%52%
1758
16th to endDay
13%6%3332433452%
1674
December1st to 15thDay
17%7%35%323135%46%
1620
16th to endDay
17%7%25%5%14346%41%
1728
January1st to 15thNight
16%5%23312345%51%
2327
16th to endNight
16%42341233452%
2496
February1st to 15thNight
14%6%2442223451%
2177
16th to endNight
15%414313346%51%
1834
March1st to 15thNight
17%424423335%47%
1980
16th to endNight
10%41332435%6%52%
2112
April1st to 15thNight
8%314424347%55%
1953
16th to endNight
11%425%32335%6%51%
1790
May1st to 15thNight
9%425%5%2435%7%48%
1619
16th to endNight
5%31332446%10%54%
1683
June1st to 15thNight
311122235%8%65%
1620
16th to endNight
431332436%9%57%
1620
July1st to 15thNight
421331336%11%57%
1620
16th to endNight
321232446%13%54%
1702
August1st to 15thNight
311222236%11%63%
1620
16th to endNight
6%4244235%6%10%46%
1894
September1st to 15thNight
9%41342445%8%51%
1980
16th to endNight
8%313313447%57%
1857
October1st to 15thNight
8%313312346%62%
1908
16th to endNight
10%21121223466%
2112
November1st to 15thNight
8%414323335%59%
2100
16th to endNight
13%41232333456%
2283
December1st to 15thNight
16%5%25%312236%48%
2340
16th to endNight
16%7%34423445%45%
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
38%27%16%24%10%
1612
16th to endDay
38%37%16%23%10%
1728
February1st to 15thDay
41%2418%22%10%
1685
16th to endDay
40%26%17%19%13%
1638
March1st to 15thDay
45%35%17%21%7%
1980
16th to endDay
43%38%16%24%5%
2112
April1st to 15thDay
39%5%9%19%16%9%
1995
16th to endDay
39%5%10%17%19%7%
2167
May1st to 15thDay
42%6%10%18%16%6%
2331
16th to endDay
40%6%13%20%17%1
2434
June1st to 15thDay
29%6%13%31%16%2
2340
16th to endDay
31%8%15%26%15%2
2340
July1st to 15thDay
31%7%19%29%11%
2201
16th to endDay
33%8%21%25%11%
2311
August1st to 15thDay
21%5%18%35%17%1
2326
16th to endDay
38%8%14%23%11%2
2302
September1st to 15thDay
36%6%14%21%12%8%
1980
16th to endDay
30%5%10%22%21%9%
1848
October1st to 15thDay
29%310%21%17%17%
1710
16th to endDay
23%2417%35%15%
1760
November1st to 15thDay
34%38%24%20%8%
1758
16th to endDay
35%35%14%26%14%
1674
December1st to 15thDay
43%18%19%19%6%
1620
16th to endDay
45%37%18%17%7%
1728
January1st to 15thNight
36%36%16%23%14%
2327
16th to endNight
36%25%16%24%14%
2496
February1st to 15thNight
37%25%15%23%15%
2187
16th to endNight
35%37%17%19%15%
1834
March1st to 15thNight
40%37%15%22%10%
1980
16th to endNight
32%5%11%19%25%7%
2112
April1st to 15thNight
29%5%10%21%19%12%
1953
16th to endNight
32%411%18%20%11%
1790
May1st to 15thNight
36%411%20%18%8%
1620
16th to endNight
24%6%20%27%17%4
1685
June1st to 15thNight
16%6%14%35%24%3
1620
16th to endNight
22%6%16%28%21%3
1620
July1st to 15thNight
21%6%20%33%15%2
1530
16th to endNight
20%6%26%32%12%1
1594
August1st to 15thNight
16%5%19%33%21%3
1610
16th to endNight
31%6%17%30%10%3
1894
September1st to 15thNight
29%5%15%24%17%7%
1980
16th to endNight
25%410%23%23%11%
1857
October1st to 15thNight
24%39%23%19%18%
1908
16th to endNight
23%2418%27%23%
2112
November1st to 15thNight
29%38%23%24%11%
2100
16th to endNight
33%26%13%27%16%
2283
December1st to 15thNight
37%210%19%20%9%
2340
16th to endNight
41%27%17%19%11%
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
17%12%32%24%13%
90
16th to endDay
18%7%45%17%10%
96
February1st to 15thDay
10%15%35%31%6%1
90
16th to endDay
14%12%46%17%8%
81
March1st to 15thDay
25%14%32%16%10%1
90
16th to endDay
12%7%38%23%16%1
96
April1st to 15thDay
15%13%27%29%13%
114
16th to endDay
16%10%28%28%14%1
277
May1st to 15thDay
11%9%31%31%12%1
468
16th to endDay
11%5%27%28%23%4
517
June1st to 15thDay
6%11%35%34%11%
495
16th to endDay
5%29%29%36%16%
495
July1st to 15thDay
5%6%33%39%14%
475
16th to endDay
41222%49%20%
515
August1st to 15thDay
6%222%51%16%
493
16th to endDay
14%7%15%40%22%
342
September1st to 15thDay
25%16%37%38%
135
16th to endDay
4314%47%31%
99
October1st to 15thDay
5%36%48%8%
90
16th to endDay
16%411%20%37%9%
96
November1st to 15thDay
30%118%30%18%1
90
16th to endDay
21%10%24%27%11%5%
90
December1st to 15thDay
32%5%13%25%17%5%
90
16th to endDay
27%14%32%19%5%1
96
January1st to 15thNight
19%9%31%30%9%
900
16th to endNight
18%9%34%32%5%
960
February1st to 15thNight
20%9%32%31%5%
779
16th to endNight
20%10%38%27%3
572
March1st to 15thNight
20%8%35%29%6%
540
16th to endNight
13%8%41%28%7%
576
April1st to 15thNight
11%7%44%29%8%
539
16th to endNight
13%7%39%26%11%1
540
May1st to 15thNight
10%7%38%32%9%1
540
16th to endNight
5%229%38%20%2
563
June1st to 15thNight
313%44%33%3
540
16th to endNight
419%42%35%6%
540
July1st to 15thNight
48%44%36%5%
510
16th to endNight
4435%48%6%
564
August1st to 15thNight
3140%46%6%
539
16th to endNight
8%6%32%43%7%
573
September1st to 15thNight
10%6%31%44%6%
540
16th to endNight
10%8%27%47%6%
504
October1st to 15thNight
10%113%41%26%5%
588
16th to endNight
11%5%22%35%22%2
704
November1st to 15thNight
10%5%29%34%19%1
700
16th to endNight
17%6%26%32%15%1
843
December1st to 15thNight
19%7%27%34%9%
900
16th to endNight
21%8%28%32%8%
960
Page generated at 2017-09-20 03:49:49. Version ac04

Copyright 2017 A. Danko


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