Monroe
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Monroe clear sky chart from 2005-11-05 to 2018-03-21.

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
53%
16269
25%
49244
19%
16224
59%
16224
33%
29191

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
37%
974
25%
2522
12%
970
45%
970
31%
1634
January16th to endNight
31%
1040
26%
2704
10%
1040
40%
1040
30%
1789
February1st to 15thNight
34%
868
23%
2396
9%
865
44%
865
29%
1553
February16th to endNight
26%
651
25%
2017
10%
651
38%
651
24%
1286
March1st to 15thNight
37%
585
25%
2145
17%
585
48%
585
24%
1265
March16th to endNight
43%
594
22%
2175
17%
594
52%
594
26%
1271
April1st to 15thNight
44%
539
25%
1797
18%
539
56%
539
34%
982
April16th to endNight
46%
540
26%
1800
22%
540
55%
540
30%
1034
May1st to 15thNight
51%
540
21%
1800
18%
540
59%
540
29%
1065
May16th to endNight
62%
563
24%
1737
24%
561
66%
561
36%
980
June1st to 15thNight
78%
540
19%
1620
21%
540
81%
540
42%
888
June16th to endNight
75%
540
22%
1620
23%
540
76%
540
36%
944
July1st to 15thNight
78%
510
19%
1530
22%
510
79%
510
38%
871
July16th to endNight
84%
564
22%
1594
26%
531
84%
531
42%
875
August1st to 15thNight
84%
539
22%
1726
26%
536
85%
536
40%
923
August16th to endNight
74%
573
20%
1910
25%
573
74%
573
28%
1159
September1st to 15thNight
72%
540
23%
1800
27%
540
73%
540
33%
1042
September16th to endNight
72%
607
32%
1960
32%
607
73%
607
38%
1075
October1st to 15thNight
65%
720
30%
2160
25%
720
69%
720
40%
1172
October16th to endNight
58%
768
37%
2304
28%
768
67%
768
43%
1225
November1st to 15thNight
55%
760
30%
2280
24%
760
60%
760
38%
1287
November16th to endNight
47%
780
33%
2375
24%
780
56%
780
35%
1362
December1st to 15thNight
40%
894
24%
2568
14%
894
48%
894
28%
1637
December16th to endNight
35%
1040
21%
2704
10%
1040
41%
1040
25%
1872

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
12%5%25%5%345%5%7%42%
49570
Night
11%42442445%7%49%
49442
TransparencyDay
39%6%10%19%18%5%
49271
Night
33%5%11%20%21%8%
49246
SeeingDay
12%417%23%28%13%
6124
Night
13%422%31%23%4
16270

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
18%6%25%42234444%
1746
16th to endDay
18%7%3431323446%
1872
February1st to 15thDay
18%7%3432433443%
1793
16th to endDay
18%8%35%423325%40%
1752
March1st to 15thDay
17%6%25%43444441%
2145
16th to endDay
11%6%35%5%3445%6%43%
2172
April1st to 15thDay
11%5%245%3445%8%44%
2151
16th to endDay
11%5%36%6%25%45%8%41%
2160
May1st to 15thDay
13%6%35%5%3445%7%38%
2151
16th to endDay
7%325%6%5%6%6%6%10%40%
2373
June1st to 15thDay
6%3245%35%7%9%10%39%
2340
16th to endDay
5%325%6%47%7%7%11%37%
2340
July1st to 15thDay
8%325%6%47%7%7%11%33%
2340
16th to endDay
7%5%26%5%47%7%8%9%33%
2466
August1st to 15thDay
7%3246%45%6%6%11%41%
2223
16th to endDay
12%425%6%5%6%6%8%9%33%
2292
September1st to 15thDay
9%4146%35%6%6%9%40%
2160
16th to endDay
9%4244345%5%8%47%
1983
October1st to 15thDay
7%3245%2345%6%53%
1800
16th to endDay
13%41321223460%
1920
November1st to 15thDay
9%5%1432245%5%53%
1908
16th to endDay
13%6%2342433450%
1905
December1st to 15thDay
18%8%26%42433439%
1706
16th to endDay
18%7%36%5%23346%37%
1872
January1st to 15thNight
15%5%14423345%48%
2522
16th to endNight
18%5%24323335%46%
2704
February1st to 15thNight
14%7%34423345%45%
2387
16th to endNight
17%6%24423345%44%
2017
March1st to 15thNight
14%5%24424347%45%
2145
16th to endNight
11%6%1442435%5%49%
2175
April1st to 15thNight
8%32332435%8%53%
1797
16th to endNight
9%5%2442435%6%50%
1800
May1st to 15thNight
9%435%5%235%5%9%46%
1799
16th to endNight
6%325%5%2445%10%49%
1737
June1st to 15thNight
42133245%7%9%54%
1620
16th to endNight
5%323435%5%6%9%49%
1620
July1st to 15thNight
6%3135%35%47%10%47%
1620
16th to endNight
5%2123245%9%13%49%
1702
August1st to 15thNight
32124245%8%13%50%
1736
16th to endNight
9%4244335%9%11%41%
1910
September1st to 15thNight
8%3145%3446%7%49%
1800
16th to endNight
7%413433346%56%
1960
October1st to 15thNight
6%3135%24246%58%
2160
16th to endNight
11%31331223461%
2304
November1st to 15thNight
10%414323446%55%
2280
16th to endNight
12%43341333454%
2375
December1st to 15thNight
16%7%24313336%46%
2568
16th to endNight
18%7%26%42334441%
2704

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%25%19%22%6%
1747
16th to endDay
43%2317%25%8%
1872
February1st to 15thDay
45%36%19%18%8%
1795
16th to endDay
47%36%16%20%5%
1752
March1st to 15thDay
45%38%15%19%6%
2145
16th to endDay
40%5%10%18%21%2
2174
April1st to 15thDay
38%410%21%17%7%
2151
16th to endDay
41%5%8%19%20%4
2160
May1st to 15thDay
45%5%10%15%17%5%
2151
16th to endDay
38%7%15%25%12%1
2377
June1st to 15thDay
35%11%13%24%15%
2340
16th to endDay
36%9%16%20%15%2
2340
July1st to 15thDay
38%8%20%22%9%1
2201
16th to endDay
39%10%17%20%11%
2311
August1st to 15thDay
33%10%17%24%13%1
2209
16th to endDay
42%8%15%19%11%2
2292
September1st to 15thDay
38%8%12%18%15%6%
2160
16th to endDay
33%5%10%20%21%7%
1983
October1st to 15thDay
30%5%7%19%21%14%
1800
16th to endDay
29%2416%32%14%
1920
November1st to 15thDay
32%38%19%27%7%
1908
16th to endDay
37%36%14%26%10%
1905
December1st to 15thDay
48%37%16%15%8%
1706
16th to endDay
48%47%18%17%4
1872
January1st to 15thNight
39%36%16%26%8%
2522
16th to endNight
41%3416%23%9%
2704
February1st to 15thNight
40%36%19%21%8%
2396
16th to endNight
42%46%17%19%9%
2017
March1st to 15thNight
38%49%16%21%8%
2145
16th to endNight
36%5%9%20%22%5%
2175
April1st to 15thNight
29%5%11%23%20%10%
1797
16th to endNight
34%5%8%21%24%6%
1800
May1st to 15thNight
34%6%10%20%19%8%
1800
16th to endNight
30%5%15%26%20%1
1739
June1st to 15thNight
24%7%17%31%18%1
1620
16th to endNight
29%7%15%23%19%3
1620
July1st to 15thNight
27%7%24%27%11%2
1530
16th to endNight
22%9%25%28%13%1
1594
August1st to 15thNight
22%9%22%26%16%3
1726
16th to endNight
33%9%19%19%14%3
1910
September1st to 15thNight
30%7%14%23%15%8%
1800
16th to endNight
28%410%17%26%11%
1960
October1st to 15thNight
27%48%18%23%16%
2160
16th to endNight
26%2414%30%20%
2304
November1st to 15thNight
29%410%18%26%10%
2280
16th to endNight
34%26%14%28%14%
2375
December1st to 15thNight
41%39%19%18%7%
2568
16th to endNight
46%37%18%19%5%
2704

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
22%11%40%17%7%1
135
16th to endDay
19%16%43%13%42
144
February1st to 15thDay
25%11%40%20%2
135
16th to endDay
25%11%41%18%2
120
March1st to 15thDay
21%14%39%24%
135
16th to endDay
7%20%30%30%8%1
114
April1st to 15thDay
16%10%28%29%13%2
270
16th to endDay
17%8%20%30%22%1
270
May1st to 15thDay
15%429%30%15%4
288
16th to endDay
8%322%29%27%9%
460
June1st to 15thDay
9%16%31%38%12%
495
16th to endDay
6%18%28%37%17%
495
July1st to 15thDay
5%16%24%41%20%
475
16th to endDay
7%1115%45%27%
515
August1st to 15thDay
7%215%46%27%
376
16th to endDay
15%315%34%30%
332
September1st to 15thDay
8%8%17%38%26%
315
16th to endDay
6%17%21%42%19%
222
October1st to 15thDay
322%28%30%14%
135
16th to endDay
13%325%25%22%9%
144
November1st to 15thDay
19%330%31%14%1
135
16th to endDay
14%7%31%25%14%7%
135
December1st to 15thDay
25%438%13%15%2
135
16th to endDay
18%15%38%21%42
144
January1st to 15thNight
19%8%29%32%9%
975
16th to endNight
21%7%36%29%5%
1040
February1st to 15thNight
18%10%32%31%6%
868
16th to endNight
21%10%37%28%3
651
March1st to 15thNight
15%7%35%34%7%
585
16th to endNight
14%5%32%32%13%
594
April1st to 15thNight
9%9%34%33%12%
539
16th to endNight
12%6%29%36%13%
540
May1st to 15thNight
10%228%40%16%1
540
16th to endNight
8%317%35%31%3
563
June1st to 15thNight
5%6%39%42%5%
540
16th to endNight
5%8%25%47%11%
540
July1st to 15thNight
6%5%28%48%11%
510
16th to endNight
6%121%55%15%
564
August1st to 15thNight
3218%53%19%
539
16th to endNight
11%324%46%13%
573
September1st to 15thNight
10%5%32%39%10%
540
16th to endNight
9%16%33%43%5%
607
October1st to 15thNight
8%117%31%34%6%
720
16th to endNight
12%420%33%24%4
768
November1st to 15thNight
12%323%35%23%2
760
16th to endNight
15%5%27%31%18%1
780
December1st to 15thNight
21%6%27%33%11%
894
16th to endNight
23%9%27%30%8%
1040
Page generated at 2018-03-22 10:34:24. Version ac04

Copyright 2018 A. Danko


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