Conner Preserve
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Conner Preserve clear sky chart from 2005-11-06 to 2024-03-01.

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
60%
24568
20%
79912
17%
24468
64%
24468
28%
49262

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
43%
753
21%
4034
17%
737
54%
737
17%
2404
January11th to 20thNight
50%
756
19%
4069
21%
740
60%
740
15%
2715
January21st to endNight
38%
828
16%
4210
15%
814
49%
814
17%
2438
February1st to 10thNight
45%
760
25%
2280
18%
760
53%
760
32%
1379
February11th to 20thNight
49%
740
23%
2219
16%
740
56%
740
34%
1287
February21st to endNight
49%
628
26%
1839
17%
628
57%
628
34%
1095
March1st to 10thNight
48%
723
30%
1987
19%
723
57%
723
43%
1116
March11th to 20thNight
51%
720
28%
1980
18%
720
59%
720
39%
1164
March21st to endNight
54%
792
30%
2178
21%
792
60%
792
42%
1230
April1st to 10thNight
55%
720
25%
1980
19%
720
60%
720
43%
1111
April11th to 20thNight
52%
711
21%
1953
15%
711
57%
711
37%
1155
April21st to endNight
60%
686
31%
1796
20%
686
65%
686
45%
1023
May1st to 10thNight
77%
540
31%
1620
26%
540
79%
540
52%
792
May11th to 20thNight
72%
531
17%
1592
13%
531
76%
531
35%
953
May21st to endNight
75%
582
24%
1744
21%
582
76%
582
38%
1005
June1st to 10thNight
70%
540
15%
1620
14%
540
70%
540
27%
1068
June11th to 20thNight
78%
540
12%
1620
12%
540
78%
540
30%
1020
June21st to endNight
72%
540
10%
1620
9%
540
72%
540
24%
1125
July1st to 10thNight
74%
525
6%
1575
6%
525
74%
525
21%
1139
July11th to 20thNight
77%
522
4%
1566
4%
522
77%
522
22%
1124
July21st to endNight
76%
591
8%
1672
9%
558
77%
558
23%
1164
August1st to 10thNight
77%
537
5%
1600
5%
534
77%
534
26%
1094
August11th to 20thNight
74%
534
6%
1768
8%
534
74%
534
21%
1206
August21st to endNight
65%
764
9%
2150
10%
764
65%
764
19%
1562
September1st to 10thNight
68%
720
8%
1980
7%
720
69%
720
21%
1411
September11th to 20thNight
63%
720
10%
1980
10%
720
64%
720
21%
1425
September21st to endNight
66%
720
20%
1980
18%
720
68%
720
26%
1325
October1st to 10thNight
62%
720
22%
1980
20%
720
64%
720
29%
1292
October11th to 20thNight
69%
720
31%
2121
31%
720
73%
720
41%
1184
October21st to endNight
62%
792
28%
2376
26%
792
67%
792
35%
1365
November1st to 10thNight
60%
740
28%
2221
24%
740
68%
740
41%
1209
November11th to 20thNight
54%
760
30%
2280
25%
760
62%
760
34%
1349
November21st to endNight
53%
760
26%
2448
24%
760
60%
760
31%
1429
December1st to 10thNight
54%
760
28%
2470
23%
760
64%
760
33%
1401
December11th to 20thNight
52%
759
25%
2936
22%
758
58%
758
25%
1698
December21st to endNight
51%
834
16%
4468
23%
817
58%
817
16%
2805

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
9%5%36%6%46%6%7%9%39%
78911
Night
9%6%35%5%35%5%7%9%43%
80500
TransparencyDay
40%7%15%19%14%6%
78634
Night
36%7%16%20%15%5%
80296
SeeingDay
9%416%25%25%20%
14447
Night
9%417%34%27%9%
24595

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
11%8%26%5%46%46%8%40%
2836
11th to 20thDay
21%9%26%5%3445%7%34%
2840
21st to endDay
11%5%36%5%345%6%9%45%
3358
February1st to 10thDay
14%5%35%5%3445%8%45%
1900
11th to 20thDay
9%4245%3345%6%54%
1848
21st to endDay
7%5%25%5%35%45%8%50%
1613
March1st to 10thDay
5%3134345%5%8%58%
1980
11th to 20thDay
7%424435%46%8%53%
1980
21st to endDay
7%4345%35%45%7%54%
2178
April1st to 10thDay
8%4245%35%6%6%9%50%
1980
11th to 20thDay
8%425%6%47%6%7%8%44%
1956
21st to endDay
5%3245%45%5%5%8%54%
2174
May1st to 10thDay
5%2244245%5%8%59%
2340
11th to 20thDay
8%5%36%6%36%6%6%10%42%
2301
21st to endDay
7%436%5%48%7%7%9%40%
2531
June1st to 10thDay
12%7%37%8%48%7%7%10%26%
2340
11th to 20thDay
5%6%26%9%5%9%8%9%12%27%
2340
21st to endDay
8%7%36%8%48%8%8%10%29%
2340
July1st to 10thDay
8%6%38%9%6%10%9%9%10%23%
2340
11th to 20thDay
7%6%38%10%6%9%9%9%12%22%
2340
21st to endDay
7%6%38%9%6%9%9%9%12%22%
2547
August1st to 10thDay
8%5%27%9%6%8%9%10%11%26%
2327
11th to 20thDay
7%6%48%9%7%10%9%9%10%22%
2128
21st to endDay
11%6%39%9%5%8%8%8%10%23%
2185
September1st to 10thDay
8%6%38%10%6%8%9%9%11%23%
1980
11th to 20thDay
10%7%48%8%5%8%6%9%10%26%
1980
21st to endDay
8%6%36%9%5%8%8%8%10%31%
1980
October1st to 10thDay
9%6%37%7%5%7%6%6%8%38%
1980
11th to 20thDay
6%4345%46%6%6%8%50%
1836
21st to endDay
7%5%25%435%5%7%9%50%
1980
November1st to 10thDay
8%425%5%345%5%7%51%
1857
11th to 20thDay
9%5%35%5%36%5%5%7%47%
1900
21st to endDay
8%5%35%5%35%6%5%9%44%
1729
December1st to 10thDay
7%425%6%35%5%7%9%46%
1710
11th to 20thDay
10%6%35%6%25%45%7%46%
2153
21st to endDay
12%8%38%7%45%6%5%7%35%
3124
January1st to 10thNight
11%7%37%6%45%5%5%7%39%
4109
11th to 20thNight
17%10%36%5%35%5%5%8%31%
4120
21st to endNight
12%7%36%5%35%5%6%8%40%
4294
February1st to 10thNight
11%7%2443346%8%46%
2280
11th to 20thNight
9%5%35%5%3445%7%50%
2218
21st to endNight
7%5%35%6%4445%8%49%
1839
March1st to 10thNight
5%425%42445%6%58%
1987
11th to 20thNight
8%3245%245%6%10%50%
1980
21st to endNight
5%5%245%245%5%7%56%
2178
April1st to 10thNight
6%4244335%6%10%53%
1980
11th to 20thNight
6%5%36%435%5%6%8%50%
1953
21st to endNight
7%314435%447%58%
1796
May1st to 10thNight
431232345%10%62%
1620
11th to 20thNight
5%426%5%45%5%7%10%48%
1592
21st to endNight
6%3235%35%6%6%10%51%
1744
June1st to 10thNight
9%5%36%6%45%6%7%10%38%
1620
11th to 20thNight
5%425%6%46%7%9%14%38%
1620
21st to endNight
6%5%26%7%37%7%10%12%34%
1620
July1st to 10thNight
6%437%7%48%8%10%14%31%
1620
11th to 20thNight
46%35%7%5%7%8%11%14%30%
1620
21st to endNight
45%36%8%6%7%8%10%13%30%
1771
August1st to 10thNight
45%25%6%5%7%7%9%14%34%
1611
11th to 20thNight
6%5%46%6%5%7%8%10%13%32%
1768
21st to endNight
9%8%36%7%46%7%9%10%31%
2150
September1st to 10thNight
6%5%26%8%5%7%8%10%14%29%
1980
11th to 20thNight
10%6%47%7%46%7%8%12%30%
1980
21st to endNight
7%6%37%7%46%6%9%10%35%
1980
October1st to 10thNight
8%6%35%6%35%7%7%8%41%
1980
11th to 20thNight
6%4245%3446%9%53%
2121
21st to endNight
8%5%25%43445%9%50%
2376
November1st to 10thNight
8%4243245%5%8%54%
2221
11th to 20thNight
9%5%26%5%35%5%47%50%
2280
21st to endNight
8%5%35%5%35%5%5%9%46%
2448
December1st to 10thNight
8%435%5%35%45%8%50%
2470
11th to 20thNight
11%6%35%43445%6%48%
3042
21st to endNight
15%8%36%6%35%5%6%8%35%
4532

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
41%48%20%19%8%
2837
11th to 20thDay
50%35%18%15%9%
2840
21st to endDay
37%48%22%22%7%
3358
February1st to 10thDay
38%6%8%18%19%12%
1900
11th to 20thDay
31%38%20%26%12%
1858
21st to endDay
31%5%10%19%23%11%
1613
March1st to 10thDay
24%5%12%25%24%11%
1980
11th to 20thDay
31%411%27%18%9%
1980
21st to endDay
31%310%25%23%8%
2178
April1st to 10thDay
30%5%16%21%20%8%
1980
11th to 20thDay
35%7%11%18%21%7%
1956
21st to endDay
28%5%10%24%27%7%
2174
May1st to 10thDay
23%413%27%23%10%
2340
11th to 20thDay
37%5%16%22%15%3
2305
21st to endDay
38%7%14%21%18%3
2531
June1st to 10thDay
51%7%19%18%5%
2340
11th to 20thDay
45%9%24%19%4
2340
21st to endDay
47%10%25%14%4
2340
July1st to 10thDay
51%12%27%9%1
2275
11th to 20thDay
52%12%27%8%1
2271
21st to endDay
47%14%26%12%1
2405
August1st to 10thDay
47%12%29%11%1
2314
11th to 20thDay
52%13%24%10%1
2128
21st to endDay
54%11%20%13%2
2185
September1st to 10thDay
51%12%22%11%3
1980
11th to 20thDay
49%10%23%14%4
1980
21st to endDay
44%10%15%18%10%3
1980
October1st to 10thDay
43%7%10%18%13%9%
1980
11th to 20thDay
31%5%9%23%24%7%
1836
21st to endDay
29%5%11%20%21%13%
1980
November1st to 10thDay
32%5%10%23%19%12%
1857
11th to 20thDay
35%5%9%20%21%9%
1900
21st to endDay
36%49%23%20%8%
1729
December1st to 10thDay
33%5%12%28%16%6%
1710
11th to 20thDay
37%49%19%17%13%
2150
21st to endDay
48%410%19%14%5%
3124
January1st to 10thNight
44%49%16%20%6%
4109
11th to 20thNight
52%37%18%15%5%
4120
21st to endNight
41%5%11%17%18%8%
4294
February1st to 10thNight
36%5%11%19%19%11%
2280
11th to 20thNight
32%5%10%20%23%10%
2219
21st to endNight
34%5%11%20%22%8%
1839
March1st to 10thNight
26%5%12%26%23%8%
1987
11th to 20thNight
30%5%14%28%14%9%
1980
21st to endNight
27%5%10%31%21%7%
2178
April1st to 10thNight
26%5%19%26%18%6%
1980
11th to 20thNight
31%5%14%25%20%5%
1953
21st to endNight
26%413%27%24%6%
1796
May1st to 10thNight
18%5%14%31%23%8%
1620
11th to 20thNight
30%8%22%22%16%2
1593
21st to endNight
27%8%18%25%20%3
1745
June1st to 10thNight
40%8%23%22%7%
1620
11th to 20thNight
32%11%31%22%3
1620
21st to endNight
38%15%26%17%5%
1620
July1st to 10thNight
40%17%32%9%2
1575
11th to 20thNight
39%17%34%9%1
1566
21st to endNight
38%15%34%12%1
1672
August1st to 10thNight
36%14%37%11%2
1600
11th to 20thNight
39%15%32%14%
1768
21st to endNight
45%13%25%15%2
2150
September1st to 10thNight
41%15%28%13%4
1980
11th to 20thNight
45%11%23%16%31
1980
21st to endNight
40%9%18%20%10%2
1980
October1st to 10thNight
37%10%13%20%13%8%
1980
11th to 20thNight
27%5%12%26%24%5%
2121
21st to endNight
32%5%10%20%23%10%
2376
November1st to 10thNight
28%413%23%21%12%
2221
11th to 20thNight
34%49%22%22%9%
2280
21st to endNight
35%410%24%19%8%
2448
December1st to 10thNight
32%5%12%29%16%5%
2470
11th to 20thNight
37%49%20%19%11%
3044
21st to endNight
47%5%12%18%14%4
4532

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
11%10%44%24%11%
270
11th to 20thDay
9%12%32%33%11%3
270
21st to endDay
16%13%40%24%7%
297
February1st to 10thDay
15%8%33%29%13%3
270
11th to 20thDay
11%7%35%29%14%4
270
21st to endDay
6%13%30%31%18%2
268
March1st to 10thDay
6%9%35%34%15%1
420
11th to 20thDay
11%7%27%30%22%3
420
21st to endDay
6%5%32%32%22%3
462
April1st to 10thDay
10%8%28%30%21%3
420
11th to 20thDay
11%6%24%32%22%6%
412
21st to endDay
6%321%35%24%10%
420
May1st to 10thDay
5%421%30%26%13%
423
11th to 20thDay
9%113%30%29%18%
447
21st to endDay
8%28%24%29%29%
485
June1st to 10thDay
15%26%20%31%26%
450
11th to 20thDay
6%25%22%31%34%
450
21st to endDay
7%2315%29%44%
450
July1st to 10thDay
7%1111%27%53%
445
11th to 20thDay
7%1111%29%51%
444
21st to endDay
10%2215%27%44%
488
August1st to 10thDay
9%2113%30%46%
446
11th to 20thDay
7%3110%27%52%
439
21st to endDay
8%25%13%33%39%
495
September1st to 10thDay
9%2413%33%39%
450
11th to 20thDay
11%2320%34%29%
450
21st to endDay
10%2420%38%27%
450
October1st to 10thDay
11%214%35%29%9%
450
11th to 20thDay
7%313%33%31%13%
450
21st to endDay
7%317%40%27%6%
495
November1st to 10thDay
10%420%33%26%7%
455
11th to 20thDay
13%5%21%37%19%5%
460
21st to endDay
11%5%28%34%19%3
289
December1st to 10thDay
5%9%34%31%16%6%
270
11th to 20thDay
16%7%33%27%16%2
270
21st to endDay
9%9%27%36%15%3
297
January1st to 10thNight
12%7%30%37%14%
760
11th to 20thNight
12%6%25%41%16%1
760
21st to endNight
16%6%32%38%8%
836
February1st to 10thNight
16%5%28%38%13%
760
11th to 20thNight
11%7%25%42%14%1
743
21st to endNight
9%5%28%47%11%
628
March1st to 10thNight
6%5%35%43%11%1
723
11th to 20thNight
10%5%27%40%17%1
720
21st to endNight
8%5%26%44%16%1
792
April1st to 10thNight
8%426%43%17%1
720
11th to 20thNight
9%5%28%43%15%1
711
21st to endNight
7%323%43%22%1
686
May1st to 10thNight
5%112%49%31%3
540
11th to 20thNight
6%211%41%35%4
531
21st to endNight
6%29%35%41%8%
584
June1st to 10thNight
11%25%27%44%12%
540
11th to 20thNight
6%1318%48%24%
540
21st to endNight
6%3214%47%28%
540
July1st to 10thNight
6%28%48%35%
525
11th to 20thNight
5%27%44%42%
522
21st to endNight
5%218%51%33%
591
August1st to 10thNight
6%217%53%31%
537
11th to 20thNight
6%218%44%40%
534
21st to endNight
12%3219%42%23%
764
September1st to 10thNight
8%25%18%45%21%
720
11th to 20thNight
12%2426%42%14%
720
21st to endNight
9%26%30%42%11%
720
October1st to 10thNight
12%113%42%27%5%
720
11th to 20thNight
7%313%40%35%3
720
21st to endNight
10%316%41%28%2
792
November1st to 10thNight
9%222%43%21%3
740
11th to 20thNight
11%321%43%19%2
760
21st to endNight
10%423%47%16%1
760
December1st to 10thNight
11%424%39%22%1
760
11th to 20thNight
10%5%24%43%18%1
760
21st to endNight
10%6%25%39%19%1
836
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