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 2018-04-23.

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
37%
16691
16%
49614
10%
16652
43%
16652
19%
34265

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
20%
972
10%
2716
5%
970
25%
970
13%
2113
January16th to endNight
21%
884
9%
2756
4%
884
27%
884
11%
2131
February1st to 15thNight
21%
761
10%
2447
4%
761
27%
761
12%
1849
February16th to endNight
27%
683
13%
2049
6%
683
34%
683
13%
1524
March1st to 15thNight
30%
780
15%
2243
9%
780
36%
780
18%
1611
March16th to endNight
36%
832
19%
2288
11%
832
43%
832
21%
1588
April1st to 15thNight
33%
649
15%
1975
9%
649
39%
649
18%
1366
April16th to endNight
39%
558
21%
1672
8%
558
50%
558
22%
1087
May1st to 15thNight
36%
540
14%
1620
8%
540
42%
540
17%
1129
May16th to endNight
46%
562
16%
1684
11%
561
51%
561
25%
1049
June1st to 15thNight
50%
540
15%
1476
10%
540
56%
540
27%
945
June16th to endNight
51%
540
17%
1440
11%
540
57%
540
29%
916
July1st to 15thNight
63%
510
16%
1360
14%
510
66%
510
35%
821
July16th to endNight
63%
564
19%
1531
16%
531
70%
531
37%
852
August1st to 15thNight
62%
539
20%
1609
15%
536
66%
536
33%
929
August16th to endNight
61%
573
22%
1740
17%
573
66%
573
32%
1018
September1st to 15thNight
58%
675
24%
1935
17%
675
62%
675
32%
1183
September16th to endNight
60%
717
25%
1980
18%
717
65%
717
32%
1225
October1st to 15thNight
45%
720
20%
2070
17%
720
49%
720
24%
1368
October16th to endNight
29%
768
18%
2391
11%
768
39%
768
18%
1634
November1st to 15thNight
37%
760
19%
2471
17%
760
43%
760
21%
1607
November16th to endNight
23%
780
15%
2542
8%
780
32%
780
14%
1850
December1st to 15thNight
19%
780
9%
2730
4%
780
26%
780
10%
2100
December16th to endNight
16%
1004
8%
2889
2%
1004
22%
1004
10%
2370

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%7%36%6%35%5%5%7%34%
49880
Night
15%8%36%5%3445%6%36%
49795
Cloud CoverDay
13%7%36%6%35%5%5%7%34%
49890
Night
15%8%36%5%3445%6%36%
49799
TransparencyDay
45%5%13%21%11%1
49579
Night
48%411%21%12%1
49614
SeeingDay
15%9%16%29%21%7%
6502
Night
17%17%19%27%15%3
16698

By Month

Percentage Cloud Cover NE (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
19%13%5%7%8%35%5%5%6%18%
1552
16th to endDay
15%16%7%9%7%45%45%5%18%
1818
February1st to 15thDay
16%12%410%7%45%445%23%
1742
16th to endDay
15%10%410%8%4446%7%23%
1710
March1st to 15thDay
17%10%47%6%35%5%5%6%27%
2035
16th to endDay
19%8%47%5%3435%6%30%
2288
April1st to 15thDay
18%7%47%7%35%45%6%29%
2312
16th to endDay
15%7%46%5%24347%38%
2402
May1st to 15thDay
15%8%47%5%35%447%33%
2331
16th to endDay
10%5%35%5%35%5%6%7%40%
2431
June1st to 15thDay
9%5%25%5%35%5%6%8%41%
2481
16th to endDay
7%5%35%6%37%6%8%9%36%
2520
July1st to 15thDay
6%4245%45%5%6%7%45%
2520
16th to endDay
7%4145%35%6%7%10%42%
2528
August1st to 15thDay
6%425%6%36%6%6%8%43%
2340
16th to endDay
8%425%5%45%6%6%10%40%
2459
September1st to 15thDay
11%5%245%3446%7%44%
2013
16th to endDay
11%4244346%6%7%44%
1980
October1st to 15thDay
14%6%26%5%23446%42%
1890
16th to endDay
19%7%246%4445%6%33%
1831
November1st to 15thDay
13%7%36%5%345%6%6%38%
1717
16th to endDay
17%10%28%5%335%5%6%29%
1743
December1st to 15thDay
16%12%7%9%6%35%5%46%22%
1560
16th to endDay
19%14%6%11%7%24445%17%
1677
January1st to 15thNight
21%13%46%6%34445%24%
2716
16th to endNight
14%12%7%9%7%46%5%5%5%22%
2756
February1st to 15thNight
16%13%5%7%7%34346%26%
2445
16th to endNight
17%11%47%6%45%445%28%
2049
March1st to 15thNight
17%8%47%5%34345%33%
2231
16th to endNight
16%7%36%5%24446%36%
2288
April1st to 15thNight
18%8%35%5%345%5%6%33%
1975
16th to endNight
15%6%25%4246%46%39%
1672
May1st to 15thNight
18%5%37%6%35%45%7%33%
1620
16th to endNight
11%5%26%5%2445%8%43%
1682
June1st to 15thNight
10%425%435%5%6%6%44%
1476
16th to endNight
9%4245%35%5%6%10%43%
1440
July1st to 15thNight
7%313424449%52%
1440
16th to endNight
5%32342446%9%52%
1637
August1st to 15thNight
4315%426%6%6%9%48%
1620
16th to endNight
9%4145%2445%7%50%
1740
September1st to 15thNight
9%5%24434446%50%
1935
16th to endNight
11%42442445%7%47%
1980
October1st to 15thNight
14%6%25%43345%7%42%
2070
16th to endNight
19%6%26%5%24445%37%
2391
November1st to 15thNight
15%6%25%5%3445%6%40%
2471
16th to endNight
20%9%37%6%34346%29%
2542
December1st to 15thNight
19%11%5%8%6%35%35%6%24%
2730
16th to endNight
22%13%5%9%6%34445%18%
2889

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
19%13%5%7%8%36%5%46%19%
1552
16th to endDay
15%15%7%9%8%35%445%18%
1818
February1st to 15thDay
16%12%410%7%45%445%24%
1742
16th to endDay
15%11%5%10%8%3446%7%23%
1710
March1st to 15thDay
18%9%5%7%6%35%45%7%27%
2046
16th to endDay
19%8%47%5%35%35%6%30%
2287
April1st to 15thDay
18%7%37%6%35%5%5%6%29%
2312
16th to endDay
15%7%35%5%24347%38%
2402
May1st to 15thDay
15%8%46%5%35%45%7%33%
2331
16th to endDay
11%5%35%5%35%5%6%7%40%
2431
June1st to 15thDay
9%5%26%5%35%5%6%8%41%
2481
16th to endDay
8%5%25%6%37%6%8%9%36%
2520
July1st to 15thDay
6%4245%36%5%7%7%46%
2520
16th to endDay
7%4245%35%6%7%10%42%
2528
August1st to 15thDay
6%426%5%36%6%5%8%43%
2340
16th to endDay
8%4245%35%6%6%10%41%
2459
September1st to 15thDay
11%4245%3445%7%45%
2013
16th to endDay
11%4244346%6%7%44%
1980
October1st to 15thDay
13%6%26%5%24446%42%
1890
16th to endDay
19%7%246%3445%6%33%
1831
November1st to 15thDay
14%7%35%5%25%5%6%6%38%
1717
16th to endDay
17%10%28%5%335%5%6%29%
1743
December1st to 15thDay
17%11%7%8%6%35%5%46%21%
1560
16th to endDay
19%13%7%11%7%24445%17%
1677
January1st to 15thNight
21%13%46%6%35%445%25%
2716
16th to endNight
14%13%7%9%7%46%45%5%22%
2756
February1st to 15thNight
16%13%5%8%6%34346%26%
2438
16th to endNight
18%10%47%6%35%445%29%
2049
March1st to 15thNight
17%9%47%5%33345%34%
2243
16th to endNight
17%6%36%5%2445%6%36%
2288
April1st to 15thNight
18%8%45%5%346%5%5%33%
1975
16th to endNight
16%6%25%4245%46%40%
1672
May1st to 15thNight
18%5%37%5%3446%7%33%
1619
16th to endNight
11%5%36%42445%8%43%
1682
June1st to 15thNight
10%425%435%5%6%7%44%
1476
16th to endNight
10%4145%35%5%6%10%43%
1440
July1st to 15thNight
7%31442445%9%52%
1440
16th to endNight
5%313425%46%9%52%
1637
August1st to 15thNight
43145%25%6%7%8%48%
1620
16th to endNight
9%4145%34348%50%
1740
September1st to 15thNight
9%4244235%46%50%
1935
16th to endNight
11%42443346%7%48%
1980
October1st to 15thNight
14%6%245%2445%7%42%
2070
16th to endNight
20%7%25%424445%37%
2391
November1st to 15thNight
15%6%35%42445%6%40%
2471
16th to endNight
20%9%46%5%34346%30%
2542
December1st to 15thNight
19%12%5%7%6%35%35%6%24%
2730
16th to endNight
22%13%5%9%7%24445%18%
2889

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
64%5%11%12%5%
1553
16th to endDay
65%5%12%11%4
1818
February1st to 15thDay
61%410%16%6%
1744
16th to endDay
58%412%17%41
1710
March1st to 15thDay
55%5%13%17%6%
2046
16th to endDay
50%411%24%7%1
2288
April1st to 15thDay
51%412%19%11%
2312
16th to endDay
43%313%22%13%4
2402
May1st to 15thDay
47%413%21%11%2
2331
16th to endDay
38%5%13%27%13%1
2435
June1st to 15thDay
36%5%15%26%14%1
2481
16th to endDay
36%8%16%19%16%2
2520
July1st to 15thDay
32%5%13%26%19%2
2371
16th to endDay
31%6%16%27%16%2
2371
August1st to 15thDay
33%5%15%29%14%1
2327
16th to endDay
34%6%15%24%16%2
2459
September1st to 15thDay
36%6%13%27%14%1
2013
16th to endDay
35%6%12%29%15%
1980
October1st to 15thDay
42%5%12%23%15%1
1890
16th to endDay
49%414%21%9%
1831
November1st to 15thDay
43%6%11%22%13%1
1717
16th to endDay
54%414%19%7%
1743
December1st to 15thDay
64%5%10%14%5%
1560
16th to endDay
66%413%10%4
1677
January1st to 15thNight
61%410%14%8%
2716
16th to endNight
63%314%13%4
2756
February1st to 15thNight
59%411%16%6%1
2447
16th to endNight
59%39%20%6%
2049
March1st to 15thNight
52%410%19%11%1
2243
16th to endNight
48%310%24%10%1
2288
April1st to 15thNight
50%310%20%14%
1975
16th to endNight
43%311%19%18%3
1672
May1st to 15thNight
50%410%20%11%2
1620
16th to endNight
39%410%26%15%2
1684
June1st to 15thNight
37%5%11%28%16%
1476
16th to endNight
35%6%13%24%18%1
1440
July1st to 15thNight
30%6%11%28%21%2
1360
16th to endNight
25%6%16%26%21%3
1531
August1st to 15thNight
29%6%15%29%17%2
1609
16th to endNight
33%412%25%20%3
1740
September1st to 15thNight
35%410%27%18%2
1935
16th to endNight
35%5%10%29%17%1
1980
October1st to 15thNight
42%5%10%22%18%1
2070
16th to endNight
49%411%24%9%
2391
November1st to 15thNight
45%412%22%13%1
2471
16th to endNight
56%312%20%6%
2542
December1st to 15thNight
62%411%14%6%
2730
16th to endNight
67%5%11%11%4
2889

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
19%9%31%26%11%1
135
16th to endDay
31%430%28%5%
144
February1st to 15thDay
28%5%35%23%7%
135
16th to endDay
24%430%31%10%
120
March1st to 15thDay
20%11%22%33%12%
231
16th to endDay
19%10%23%32%11%2
352
April1st to 15thDay
19%13%23%30%12%1
330
16th to endDay
18%12%18%30%14%5%
289
May1st to 15thDay
18%12%16%28%20%3
288
16th to endDay
12%10%14%28%27%7%
331
June1st to 15thDay
8%13%10%38%23%4
456
16th to endDay
12%14%12%32%21%7%
495
July1st to 15thDay
6%9%7%32%34%10%
475
16th to endDay
6%11%5%26%35%13%
388
August1st to 15thDay
10%7%429%34%14%
313
16th to endDay
11%6%6%25%34%15%
332
September1st to 15thDay
11%5%11%22%29%18%
315
16th to endDay
16%7%10%15%29%20%
314
October1st to 15thDay
14%8%15%26%23%10%
315
16th to endDay
22%7%22%29%15%1
247
November1st to 15thDay
18%6%17%25%25%5%
135
16th to endDay
19%9%25%38%6%
132
December1st to 15thDay
15%16%34%26%5%1
90
16th to endDay
21%5%46%25%1
140
January1st to 15thNight
21%20%27%22%7%
975
16th to endNight
16%20%27%28%5%
884
February1st to 15thNight
21%17%28%26%5%
764
16th to endNight
20%17%23%30%7%
683
March1st to 15thNight
18%18%23%29%9%
780
16th to endNight
18%18%18%30%11%2
832
April1st to 15thNight
19%18%22%30%7%1
649
16th to endNight
18%18%18%28%12%2
558
May1st to 15thNight
17%18%16%26%17%2
540
16th to endNight
11%18%13%29%20%5%
563
June1st to 15thNight
12%17%12%34%20%2
540
16th to endNight
10%17%12%32%22%3
540
July1st to 15thNight
9%12%7%31%32%6%
510
16th to endNight
5%17%7%34%27%6%
564
August1st to 15thNight
7%11%9%35%26%8%
539
16th to endNight
9%9%9%25%36%9%
573
September1st to 15thNight
11%10%10%26%30%9%
675
16th to endNight
12%9%10%24%32%9%
717
October1st to 15thNight
19%12%16%26%19%6%
720
16th to endNight
22%15%26%27%7%
768
November1st to 15thNight
15%18%23%26%12%3
760
16th to endNight
23%22%25%19%8%
780
December1st to 15thNight
23%21%28%20%5%
780
16th to endNight
23%19%29%21%5%
1004
Page generated at 2018-04-24 10:03:01. Version ac04

Copyright 2018 A. Danko


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