Coyle Field
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coyle Field clear sky chart from 2005-11-06 to 2024-11-06.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	16% 7% 2 6% 4 4 4 4 6% 7% 40%	101274
	Night	16% 7% 2 6% 4 4 4 3 5% 7% 42%	97780
Transparency	Day	41% 6% 12% 23% 16% 3	104832
	Night	41% 5% 11% 23% 17% 3	102311
Seeing	Day	18% 10% 29% 25% 13% 4	15090
	Night	18% 8% 30% 31% 12% 1	24294

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	15% 9% 2 5% 3 3 3 3 4 5% 47%	2517
	11th to 20th	Day	15% 8% 3 8% 5% 4 4 3 5% 5% 40%	2520
	21st to end	Day	23% 11% 3 7% 4 3 3 2 4 5% 35%	3124
February	1st to 10th	Day	15% 9% 3 6% 5% 3 4 4 5% 7% 40%	1724
	11th to 20th	Day	17% 8% 2 6% 4 3 4 4 4 6% 41%	1848
	21st to end	Day	17% 9% 3 7% 4 4 3 3 4 5% 40%	1570
March	1st to 10th	Day	26% 8% 2 5% 3 3 3 3 3 5% 39%	3116
	11th to 20th	Day	9% 5% 2 5% 5% 4 4 4 6% 7% 49%	3384
	21st to end	Day	20% 7% 2 5% 3 4 3 3 4 5% 43%	4102
April	1st to 10th	Day	17% 7% 2 5% 4 4 4 4 5% 6% 41%	2280
	11th to 20th	Day	14% 7% 2 5% 4 4 4 4 5% 9% 43%	2254
	21st to end	Day	17% 7% 2 6% 4 3 4 4 6% 7% 40%	2280
May	1st to 10th	Day	24% 10% 3 7% 4 4 3 4 5% 8% 28%	4064
	11th to 20th	Day	26% 8% 3 6% 4 4 4 3 4 6% 31%	4333
	21st to end	Day	12% 6% 3 5% 4 4 4 4 6% 9% 42%	4837
June	1st to 10th	Day	12% 7% 2 5% 5% 5% 5% 4 7% 9% 39%	2660
	11th to 20th	Day	12% 6% 2 6% 5% 4 5% 4 7% 9% 39%	2660
	21st to end	Day	10% 5% 2 5% 6% 5% 5% 5% 7% 9% 41%	2660
July	1st to 10th	Day	8% 5% 2 6% 5% 6% 6% 6% 9% 11% 36%	4440
	11th to 20th	Day	13% 6% 2 6% 5% 5% 6% 5% 7% 9% 36%	4440
	21st to end	Day	12% 8% 3 8% 6% 6% 7% 5% 7% 8% 30%	4814
August	1st to 10th	Day	17% 7% 3 8% 5% 5% 6% 4 7% 9% 30%	4024
	11th to 20th	Day	13% 6% 3 6% 5% 5% 5% 5% 6% 8% 38%	3730
	21st to end	Day	9% 5% 2 6% 4 5% 5% 4 7% 10% 43%	4180
September	1st to 10th	Day	14% 6% 2 5% 3 5% 4 3 5% 7% 44%	2280
	11th to 20th	Day	12% 5% 2 5% 4 4 4 2 5% 7% 49%	2212
	21st to end	Day	19% 8% 2 7% 4 4 4 4 4 7% 38%	2090
October	1st to 10th	Day	20% 6% 2 5% 3 3 4 3 4 6% 44%	1967
	11th to 20th	Day	16% 5% 3 4 2 3 3 2 4 6% 51%	1900
	21st to end	Day	17% 6% 2 5% 3 4 3 3 4 6% 47%	1981
November	1st to 10th	Day	13% 5% 2 5% 4 3 3 3 4 6% 51%	1717
	11th to 20th	Day	16% 5% 2 6% 4 3 3 3 5% 6% 47%	1710
	21st to end	Day	15% 5% 2 5% 5% 4 4 4 5% 7% 46%	1658
December	1st to 10th	Day	19% 7% 2 6% 3 3 3 3 5% 7% 40%	1520
	11th to 20th	Day	19% 7% 2 5% 4 2 3 3 5% 5% 45%	1906
	21st to end	Day	15% 7% 2 5% 3 4 5% 5% 6% 8% 38%	2772
January	1st to 10th	Night	17% 7% 2 5% 3 3 3 3 5% 6% 47%	4429
	11th to 20th	Night	18% 9% 2 5% 4 3 3 3 4 5% 44%	4437
	21st to end	Night	21% 10% 3 6% 4 4 4 3 4 5% 36%	4532
February	1st to 10th	Night	17% 9% 3 5% 4 4 4 3 4 6% 42%	2454
	11th to 20th	Night	18% 8% 2 4 4 3 4 3 5% 5% 42%	2218
	21st to end	Night	19% 6% 2 6% 4 3 3 3 5% 6% 43%	1884
March	1st to 10th	Night	22% 12% 2 6% 4 3 2 2 4 6% 37%	3724
	11th to 20th	Night	13% 5% 3 6% 5% 4 4 3 5% 5% 48%	3560
	21st to end	Night	18% 10% 2 7% 4 3 3 2 3 4 43%	3530
April	1st to 10th	Night	17% 8% 3 7% 3 4 4 4 4 6% 42%	1900
	11th to 20th	Night	14% 8% 3 7% 4 3 4 3 4 6% 43%	1875
	21st to end	Night	17% 6% 2 5% 3 4 4 3 6% 8% 42%	1900
May	1st to 10th	Night	21% 10% 4 8% 5% 4 4 3 5% 7% 29%	2876
	11th to 20th	Night	26% 9% 3 6% 4 4 4 3 5% 6% 31%	2575
	21st to end	Night	13% 8% 3 7% 5% 3 4 4 5% 8% 41%	2738
June	1st to 10th	Night	14% 6% 3 6% 4 4 4 4 5% 8% 41%	1520
	11th to 20th	Night	10% 6% 2 7% 6% 5% 5% 3 6% 8% 41%	1520
	21st to end	Night	8% 6% 2 5% 4 5% 4 5% 7% 11% 42%	1520
July	1st to 10th	Night	7% 6% 3 10% 7% 4 5% 5% 8% 9% 34%	2520
	11th to 20th	Night	11% 7% 3 6% 5% 5% 4 4 7% 11% 38%	2520
	21st to end	Night	14% 8% 3 7% 5% 5% 4 4 7% 9% 34%	2739
August	1st to 10th	Night	20% 8% 2 7% 5% 4 4 4 6% 8% 31%	2870
	11th to 20th	Night	12% 6% 2 6% 4 4 4 4 5% 7% 45%	3097
	21st to end	Night	8% 5% 2 5% 4 4 4 4 6% 7% 51%	3476
September	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 6% 45%	1900
	11th to 20th	Night	11% 5% 2 5% 3 3 3 3 5% 7% 52%	1966
	21st to end	Night	19% 8% 2 6% 3 3 4 3 5% 7% 40%	2090
October	1st to 10th	Night	18% 7% 2 6% 3 3 3 3 4 5% 45%	2209
	11th to 20th	Night	15% 4 2 5% 3 3 3 3 5% 6% 51%	2280
	21st to end	Night	17% 6% 2 5% 3 3 3 3 5% 5% 48%	2616
November	1st to 10th	Night	11% 6% 2 5% 3 4 3 3 5% 6% 52%	2483
	11th to 20th	Night	16% 6% 2 6% 3 3 3 3 4 6% 47%	2470
	21st to end	Night	13% 6% 2 5% 4 4 4 3 5% 6% 47%	2520
December	1st to 10th	Night	19% 7% 3 6% 3 4 4 3 5% 5% 41%	2660
	11th to 20th	Night	17% 5% 2 6% 5% 4 4 3 5% 7% 42%	3288
	21st to end	Night	16% 8% 3 6% 4 4 4 4 6% 6% 38%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	40% 4 10% 25% 18% 4	2518
	11th to 20th	Day	45% 4 9% 23% 15% 3	2520
	21st to end	Day	53% 4 8% 22% 11% 2	3124
February	1st to 10th	Day	44% 5% 12% 25% 13% 1	1724
	11th to 20th	Day	43% 4 9% 24% 16% 3	1857
	21st to end	Day	47% 4 9% 21% 14% 5%	1570
March	1st to 10th	Day	48% 4 9% 27% 10% 2	3119
	11th to 20th	Day	32% 5% 11% 31% 18% 3	3384
	21st to end	Day	44% 4 8% 18% 21% 5%	4102
April	1st to 10th	Day	43% 6% 10% 20% 16% 6%	2280
	11th to 20th	Day	39% 6% 14% 22% 17% 3	2254
	21st to end	Day	42% 6% 11% 19% 18% 4	2280
May	1st to 10th	Day	54% 7% 11% 17% 9% 1	4078
	11th to 20th	Day	54% 5% 12% 20% 8% 1	4337
	21st to end	Day	37% 7% 13% 24% 17% 2	4837
June	1st to 10th	Day	40% 9% 13% 21% 15% 2	2660
	11th to 20th	Day	39% 8% 13% 26% 12% 2	2660
	21st to end	Day	37% 10% 13% 22% 17% 1	2660
July	1st to 10th	Day	39% 11% 17% 19% 13% 2	4370
	11th to 20th	Day	42% 7% 19% 21% 11% 1	4365
	21st to end	Day	48% 8% 11% 18% 13% 1	4661
August	1st to 10th	Day	49% 6% 16% 20% 9%	4010
	11th to 20th	Day	41% 6% 13% 26% 12% 1	3766
	21st to end	Day	34% 6% 12% 29% 17% 2	4180
September	1st to 10th	Day	38% 6% 13% 20% 21% 3	2280
	11th to 20th	Day	35% 4 10% 24% 24% 3	2212
	21st to end	Day	46% 5% 9% 18% 19% 3	2090
October	1st to 10th	Day	36% 4 10% 20% 26% 5%	3266
	11th to 20th	Day	26% 2 8% 24% 32% 7%	3140
	21st to end	Day	26% 3 13% 26% 26% 5%	3245
November	1st to 10th	Day	35% 3 12% 27% 19% 3	1717
	11th to 20th	Day	39% 3 10% 22% 24% 3	1710
	21st to end	Day	39% 4 11% 30% 13% 3	1658
December	1st to 10th	Day	43% 4 15% 22% 14% 1	1520
	11th to 20th	Day	41% 4 12% 26% 15% 3	1906
	21st to end	Day	42% 6% 12% 25% 14% 1	2772
January	1st to 10th	Night	38% 4 9% 30% 14% 4	4429
	11th to 20th	Night	44% 4 10% 25% 14% 3	4437
	21st to end	Night	50% 4 7% 24% 14% 2	4532
February	1st to 10th	Night	43% 4 13% 23% 14% 2	2454
	11th to 20th	Night	44% 4 9% 20% 18% 6%	2220
	21st to end	Night	42% 4 8% 23% 18% 5%	1884
March	1st to 10th	Night	51% 3 8% 23% 13% 3	3734
	11th to 20th	Night	37% 5% 12% 26% 17% 4	3561
	21st to end	Night	46% 3 7% 16% 23% 4	3530
April	1st to 10th	Night	44% 5% 9% 20% 18% 5%	1900
	11th to 20th	Night	42% 5% 9% 21% 19% 4	1875
	21st to end	Night	41% 5% 10% 20% 20% 4	1900
May	1st to 10th	Night	54% 6% 10% 19% 10% 1	2882
	11th to 20th	Night	54% 6% 11% 17% 10% 2	2576
	21st to end	Night	41% 6% 15% 19% 17% 2	2739
June	1st to 10th	Night	41% 7% 11% 21% 19% 1	1520
	11th to 20th	Night	40% 8% 11% 26% 14% 2	1520
	21st to end	Night	35% 7% 15% 25% 16% 2	1520
July	1st to 10th	Night	45% 8% 16% 19% 10% 2	2480
	11th to 20th	Night	39% 6% 18% 26% 9% 1	2472
	21st to end	Night	47% 5% 15% 18% 14% 1	2651
August	1st to 10th	Night	50% 6% 19% 16% 9% 1	2860
	11th to 20th	Night	38% 5% 12% 32% 11% 1	3127
	21st to end	Night	31% 5% 11% 31% 21% 1	3476
September	1st to 10th	Night	39% 6% 12% 20% 20% 3	1900
	11th to 20th	Night	32% 5% 11% 24% 23% 4	1966
	21st to end	Night	44% 5% 8% 21% 19% 2	2090
October	1st to 10th	Night	38% 3 11% 23% 22% 3	3690
	11th to 20th	Night	24% 3 10% 27% 31% 6%	3779
	21st to end	Night	26% 3 11% 31% 25% 5%	4302
November	1st to 10th	Night	34% 4 10% 26% 20% 5%	2483
	11th to 20th	Night	40% 5% 8% 21% 21% 5%	2470
	21st to end	Night	37% 4 12% 27% 18% 2	2520
December	1st to 10th	Night	44% 5% 11% 23% 15% 2	2660
	11th to 20th	Night	41% 4 13% 19% 19% 4	3288
	21st to end	Night	44% 6% 14% 24% 11% 1	4884

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	18% 21% 38% 17% 5% 1	180
	11th to 20th	Day	21% 29% 31% 15% 4	180
	21st to end	Day	25% 16% 34% 19% 5% 1	297
February	1st to 10th	Day	23% 19% 41% 13% 5%	284
	11th to 20th	Day	25% 18% 41% 14% 2	456
	21st to end	Day	25% 20% 34% 18% 3	382
March	1st to 10th	Day	20% 19% 35% 21% 4 1	460
	11th to 20th	Day	17% 22% 38% 16% 5% 2	460
	21st to end	Day	24% 17% 32% 21% 6%	506
April	1st to 10th	Day	21% 17% 37% 18% 6% 2	460
	11th to 20th	Day	18% 14% 38% 21% 6% 2	452
	21st to end	Day	23% 14% 35% 19% 7% 2	460
May	1st to 10th	Day	26% 14% 30% 19% 9% 2	463
	11th to 20th	Day	23% 8% 34% 24% 8% 2	487
	21st to end	Day	19% 5% 23% 27% 21% 5%	529
June	1st to 10th	Day	14% 6% 30% 29% 17% 3	490
	11th to 20th	Day	12% 7% 30% 31% 13% 5%	490
	21st to end	Day	12% 4 27% 35% 18% 4	490
July	1st to 10th	Day	13% 2 20% 32% 24% 9%	485
	11th to 20th	Day	8% 2 19% 36% 27% 9%	484
	21st to end	Day	12% 3 24% 34% 20% 6%	532
August	1st to 10th	Day	13% 3 23% 31% 21% 8%	486
	11th to 20th	Day	12% 3 18% 31% 27% 9%	479
	21st to end	Day	12% 4 19% 32% 22% 11%	539
September	1st to 10th	Day	17% 5% 22% 25% 18% 12%	490
	11th to 20th	Day	13% 2 23% 33% 19% 10%	490
	21st to end	Day	25% 7% 24% 26% 14% 5%	490
October	1st to 10th	Day	24% 6% 23% 24% 17% 7%	490
	11th to 20th	Day	17% 11% 28% 25% 15% 4	490
	21st to end	Day	19% 10% 31% 24% 12% 3	482
November	1st to 10th	Day	15% 10% 32% 27% 12% 3	381
	11th to 20th	Day	18% 15% 34% 24% 8%	370
	21st to end	Day	17% 13% 31% 26% 11% 2	318
December	1st to 10th	Day	25% 18% 36% 12% 8% 1	180
	11th to 20th	Day	26% 17% 35% 18% 4 1	180
	21st to end	Day	23% 15% 31% 21% 9% 2	198
January	1st to 10th	Night	19% 14% 38% 23% 5%	760
	11th to 20th	Night	22% 15% 34% 26% 4	760
	21st to end	Night	18% 14% 40% 25% 3	836
February	1st to 10th	Night	21% 13% 37% 27% 3	760
	11th to 20th	Night	23% 17% 40% 18% 1	743
	21st to end	Night	23% 16% 35% 23% 3	628
March	1st to 10th	Night	20% 14% 37% 24% 4	760
	11th to 20th	Night	21% 12% 38% 23% 5% 1	760
	21st to end	Night	21% 7% 42% 23% 7%	836
April	1st to 10th	Night	22% 14% 37% 21% 6%	760
	11th to 20th	Night	19% 10% 34% 31% 6%	751
	21st to end	Night	19% 7% 35% 32% 6% 1	760
May	1st to 10th	Night	21% 10% 33% 28% 8% 1	599
	11th to 20th	Night	23% 8% 32% 31% 6%	428
	21st to end	Night	19% 2 18% 39% 19% 2	411
June	1st to 10th	Night	18% 4 24% 37% 16% 2	380
	11th to 20th	Night	13% 2 20% 45% 19%	380
	21st to end	Night	9% 3 22% 48% 17% 1	380
July	1st to 10th	Night	12% 3 17% 45% 21% 2	370
	11th to 20th	Night	10% 3 15% 43% 27% 2	368
	21st to end	Night	11% 1 18% 48% 21% 2	416
August	1st to 10th	Night	11% 3 13% 45% 26% 2	586
	11th to 20th	Night	12% 2 17% 39% 27% 2	750
	21st to end	Night	13% 2 14% 40% 26% 5%	836
September	1st to 10th	Night	15% 3 19% 36% 23% 4	760
	11th to 20th	Night	15% 3 16% 35% 27% 6%	760
	21st to end	Night	24% 2 19% 33% 20% 1	760
October	1st to 10th	Night	21% 5% 24% 28% 19% 4	760
	11th to 20th	Night	18% 7% 25% 35% 14% 1	760
	21st to end	Night	19% 7% 34% 28% 11% 1	836
November	1st to 10th	Night	14% 7% 34% 31% 12% 1	764
	11th to 20th	Night	19% 12% 31% 30% 8% 1	760
	21st to end	Night	14% 11% 36% 28% 9% 1	760
December	1st to 10th	Night	24% 12% 33% 22% 8% 1	760
	11th to 20th	Night	19% 11% 38% 26% 6%	760
	21st to end	Night	19% 11% 37% 29% 3	836

Page generated at 2024-11-03 13:19:03. Version ac07

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