Murfreesboro
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Murfreesboro clear sky chart from 2005-11-06 to 2025-07-06.

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	13% 8% 3 7% 5% 5% 5% 4 6% 7% 39%	120648
	Night	13% 8% 3 7% 4 4 4 3 5% 7% 42%	118186
Transparency	Day	42% 6% 10% 21% 16% 3	124384
	Night	40% 5% 10% 22% 18% 4	122577
Seeing	Day	17% 12% 23% 23% 18% 8%	15894
	Night	17% 9% 24% 29% 18% 3	25395

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	14% 12% 6% 12% 5% 4 5% 4 4 4 29%	4056
	11th to 20th	Day	16% 9% 5% 11% 4 4 4 2 3 4 38%	4060
	21st to end	Day	20% 9% 5% 6% 3 3 4 3 5% 7% 36%	4857
February	1st to 10th	Day	19% 11% 4 8% 5% 4 4 2 4 5% 34%	2000
	11th to 20th	Day	20% 13% 4 8% 4 4 3 3 4 5% 32%	1948
	21st to end	Day	20% 9% 3 6% 5% 3 4 2 4 5% 37%	1650
March	1st to 10th	Day	17% 11% 3 8% 5% 4 4 3 5% 5% 34%	4480
	11th to 20th	Day	12% 8% 2 7% 4 4 4 3 4 5% 47%	4812
	21st to end	Day	12% 7% 3 7% 5% 4 5% 4 5% 7% 42%	5686
April	1st to 10th	Day	12% 6% 2 5% 4 4 3 4 6% 7% 44%	2400
	11th to 20th	Day	13% 7% 2 6% 5% 4 4 3 5% 6% 45%	2374
	21st to end	Day	12% 8% 2 7% 5% 5% 5% 3 5% 7% 40%	2459
May	1st to 10th	Day	18% 8% 3 7% 5% 5% 5% 4 6% 9% 29%	5862
	11th to 20th	Day	14% 9% 4 9% 6% 6% 6% 4 6% 7% 29%	5861
	21st to end	Day	15% 8% 3 7% 5% 4 4 4 5% 7% 38%	6433
June	1st to 10th	Day	8% 7% 2 7% 5% 5% 5% 5% 7% 9% 40%	2600
	11th to 20th	Day	4 4 2 6% 5% 6% 6% 6% 7% 10% 45%	2694
	21st to end	Day	5% 5% 2 7% 5% 5% 6% 5% 8% 12% 40%	2800
July	1st to 10th	Day	5% 5% 2 7% 6% 6% 7% 6% 9% 10% 36%	4511
	11th to 20th	Day	8% 5% 2 7% 6% 6% 6% 5% 8% 10% 36%	4189
	21st to end	Day	15% 10% 4 9% 7% 7% 6% 5% 6% 8% 23%	4466
August	1st to 10th	Day	4 4 2 5% 5% 5% 6% 4 8% 10% 48%	3947
	11th to 20th	Day	6% 4 2 6% 5% 6% 7% 5% 8% 11% 40%	3729
	21st to end	Day	6% 4 2 4 4 4 5% 4 6% 7% 53%	4180
September	1st to 10th	Day	11% 6% 3 7% 6% 5% 6% 5% 5% 7% 39%	2231
	11th to 20th	Day	13% 6% 2 7% 4 5% 5% 4 5% 6% 42%	2090
	21st to end	Day	11% 6% 2 6% 4 4 4 3 6% 6% 48%	2090
October	1st to 10th	Day	10% 6% 2 5% 3 3 4 3 4 6% 54%	2090
	11th to 20th	Day	12% 5% 2 5% 3 3 3 3 4 7% 54%	2081
	21st to end	Day	16% 5% 2 6% 4 3 4 3 4 6% 46%	1881
November	1st to 10th	Day	12% 5% 2 3 2 3 4 3 4 6% 55%	1762
	11th to 20th	Day	13% 8% 2 5% 4 3 3 3 5% 7% 48%	1800
	21st to end	Day	14% 8% 3 6% 3 3 4 4 5% 5% 44%	1800
December	1st to 10th	Day	14% 8% 3 7% 4 4 4 4 5% 5% 43%	2930
	11th to 20th	Day	17% 12% 5% 11% 5% 5% 4 3 3 4 31%	3373
	21st to end	Day	16% 11% 5% 9% 5% 5% 5% 4 6% 8% 28%	4466
January	1st to 10th	Night	15% 11% 4 10% 4 3 4 3 4 6% 36%	5889
	11th to 20th	Night	18% 9% 3 7% 5% 4 3 2 3 4 41%	5900
	21st to end	Night	18% 10% 4 7% 4 3 3 3 4 5% 40%	6095
February	1st to 10th	Night	20% 11% 3 7% 4 4 3 3 5% 6% 34%	2400
	11th to 20th	Night	22% 10% 4 6% 5% 4 4 2 4 4 35%	2338
	21st to end	Night	22% 10% 2 6% 4 4 3 3 6% 6% 35%	1980
March	1st to 10th	Night	19% 10% 3 7% 5% 4 4 3 5% 7% 33%	5373
	11th to 20th	Night	11% 6% 2 5% 3 4 4 3 6% 6% 49%	5146
	21st to end	Night	13% 8% 2 7% 5% 5% 4 3 5% 6% 42%	5284
April	1st to 10th	Night	12% 5% 3 6% 4 4 4 3 6% 8% 46%	2000
	11th to 20th	Night	15% 7% 2 4 3 3 3 3 5% 7% 49%	1975
	21st to end	Night	12% 6% 2 7% 5% 4 5% 4 5% 7% 45%	1940
May	1st to 10th	Night	13% 9% 3 8% 6% 5% 5% 4 7% 8% 32%	4033
	11th to 20th	Night	14% 9% 4 9% 6% 5% 5% 4 6% 8% 30%	4032
	21st to end	Night	11% 7% 3 8% 5% 6% 5% 4 7% 8% 37%	4421
June	1st to 10th	Night	6% 6% 3 7% 6% 5% 5% 3 6% 10% 44%	1800
	11th to 20th	Night	3 3 1 5% 4 4 4 4 8% 10% 52%	1696
	21st to end	Night	4 4 1 6% 5% 3 5% 5% 6% 11% 49%	1600
July	1st to 10th	Night	7% 5% 2 6% 6% 5% 6% 6% 8% 12% 39%	2570
	11th to 20th	Night	7% 6% 2 7% 5% 4 4 4 8% 11% 43%	2768
	21st to end	Night	10% 10% 4 9% 7% 6% 6% 5% 7% 9% 26%	3087
August	1st to 10th	Night	4 3 1 4 3 4 4 3 6% 10% 57%	2977
	11th to 20th	Night	5% 4 2 5% 4 4 5% 5% 8% 12% 48%	3100
	21st to end	Night	5% 3 1 5% 3 4 5% 3 6% 9% 55%	3476
September	1st to 10th	Night	9% 6% 3 6% 4 4 4 4 5% 7% 47%	1928
	11th to 20th	Night	11% 6% 2 7% 4 5% 4 3 4 8% 44%	2090
	21st to end	Night	10% 5% 2 5% 3 4 4 3 5% 7% 52%	2090
October	1st to 10th	Night	10% 4 1 4 3 3 3 3 4 6% 59%	2090
	11th to 20th	Night	15% 5% 2 5% 4 4 3 3 4 6% 51%	2093
	21st to end	Night	15% 6% 2 5% 3 3 3 3 4 6% 49%	2717
November	1st to 10th	Night	13% 5% 2 6% 4 3 3 3 4 5% 53%	2536
	11th to 20th	Night	12% 7% 2 5% 3 3 3 2 5% 8% 49%	2600
	21st to end	Night	15% 8% 3 5% 4 3 4 4 5% 5% 45%	2600
December	1st to 10th	Night	17% 10% 3 8% 4 3 3 3 4 4 40%	4250
	11th to 20th	Night	21% 10% 3 6% 4 3 3 2 4 4 40%	4822
	21st to end	Night	15% 12% 4 9% 5% 5% 5% 4 5% 6% 30%	6490

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	57% 4 10% 17% 11% 1	4057
	11th to 20th	Day	51% 3 5% 18% 21% 1	4060
	21st to end	Day	48% 4 8% 22% 14% 5%	4857
February	1st to 10th	Day	54% 5% 7% 18% 14% 2	2000
	11th to 20th	Day	56% 3 7% 17% 14% 3	1958
	21st to end	Day	50% 4 8% 16% 17% 5%	1650
March	1st to 10th	Day	51% 4 6% 13% 16% 9%	4480
	11th to 20th	Day	40% 4 7% 21% 20% 8%	4812
	21st to end	Day	41% 5% 9% 28% 16% 1	5688
April	1st to 10th	Day	38% 7% 10% 24% 18% 4	2400
	11th to 20th	Day	38% 6% 8% 21% 22% 5%	2374
	21st to end	Day	42% 6% 10% 25% 15% 2	2459
May	1st to 10th	Day	50% 8% 13% 19% 10% 1	5897
	11th to 20th	Day	51% 9% 13% 19% 9%	5865
	21st to end	Day	45% 7% 8% 21% 16% 2	6447
June	1st to 10th	Day	37% 10% 12% 22% 17% 2	2600
	11th to 20th	Day	32% 10% 17% 22% 17% 2	2694
	21st to end	Day	34% 11% 17% 19% 16% 4	2800
July	1st to 10th	Day	37% 11% 19% 23% 9% 2	4442
	11th to 20th	Day	39% 8% 18% 25% 8% 2	4117
	21st to end	Day	56% 9% 12% 16% 6% 1	4324
August	1st to 10th	Day	27% 8% 15% 32% 16% 1	3934
	11th to 20th	Day	34% 9% 14% 26% 16% 2	3765
	21st to end	Day	29% 7% 11% 31% 21% 2	4179
September	1st to 10th	Day	41% 9% 11% 17% 17% 5%	2231
	11th to 20th	Day	41% 7% 10% 22% 17% 3	2090
	21st to end	Day	36% 6% 12% 21% 20% 5%	2090
October	1st to 10th	Day	24% 5% 5% 17% 39% 11%	3480
	11th to 20th	Day	23% 3 6% 23% 32% 13%	3425
	21st to end	Day	30% 4 7% 23% 29% 8%	3081
November	1st to 10th	Day	31% 6% 9% 22% 28% 5%	1762
	11th to 20th	Day	37% 4 6% 23% 25% 6%	1800
	21st to end	Day	41% 5% 6% 24% 20% 4	1800
December	1st to 10th	Day	43% 5% 5% 26% 20% 2	2930
	11th to 20th	Day	57% 4 8% 17% 12% 3	3370
	21st to end	Day	52% 6% 11% 22% 7% 2	4466
January	1st to 10th	Night	49% 4 10% 20% 16% 1	5889
	11th to 20th	Night	47% 5% 6% 17% 21% 4	5900
	21st to end	Night	48% 3 6% 21% 17% 5%	6095
February	1st to 10th	Night	51% 4 10% 17% 16% 1	2400
	11th to 20th	Night	55% 3 7% 17% 15% 4	2339
	21st to end	Night	50% 4 8% 15% 17% 5%	1980
March	1st to 10th	Night	51% 5% 7% 14% 18% 5%	5373
	11th to 20th	Night	35% 4 7% 21% 20% 13%	5146
	21st to end	Night	44% 4 9% 26% 16% 2	5284
April	1st to 10th	Night	35% 6% 12% 23% 21% 3	2000
	11th to 20th	Night	35% 5% 9% 21% 23% 7%	1975
	21st to end	Night	38% 6% 11% 26% 18% 2	1940
May	1st to 10th	Night	48% 8% 13% 20% 10% 1	4060
	11th to 20th	Night	50% 9% 13% 16% 11%	4033
	21st to end	Night	42% 9% 13% 22% 14% 1	4429
June	1st to 10th	Night	37% 7% 12% 26% 16% 3	1800
	11th to 20th	Night	24% 8% 18% 31% 17% 3	1696
	21st to end	Night	27% 10% 17% 27% 15% 4	1600
July	1st to 10th	Night	34% 10% 20% 25% 9% 2	2530
	11th to 20th	Night	33% 8% 18% 30% 8% 3	2717
	21st to end	Night	52% 10% 13% 16% 8% 1	2988
August	1st to 10th	Night	22% 7% 12% 37% 21% 1	2966
	11th to 20th	Night	27% 8% 20% 29% 15% 1	3130
	21st to end	Night	25% 7% 12% 31% 22% 3	3476
September	1st to 10th	Night	34% 8% 12% 22% 18% 6%	1928
	11th to 20th	Night	38% 6% 12% 18% 24% 2	2090
	21st to end	Night	31% 6% 10% 23% 23% 6%	2090
October	1st to 10th	Night	23% 5% 6% 18% 36% 12%	3480
	11th to 20th	Night	22% 3 5% 22% 30% 18%	3476
	21st to end	Night	25% 3 6% 25% 32% 10%	4467
November	1st to 10th	Night	34% 4 9% 21% 25% 7%	2536
	11th to 20th	Night	35% 4 8% 20% 27% 7%	2600
	21st to end	Night	42% 4 6% 23% 20% 5%	2600
December	1st to 10th	Night	48% 4 6% 16% 24% 2	4250
	11th to 20th	Night	49% 3 6% 21% 19% 2	4824
	21st to end	Night	53% 5% 10% 21% 10% 1	6490

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	24% 24% 34% 13% 5%	300
	11th to 20th	Day	29% 28% 28% 11% 3 1	300
	21st to end	Day	25% 25% 38% 11% 2	330
February	1st to 10th	Day	30% 19% 35% 13% 2 1	300
	11th to 20th	Day	36% 25% 29% 8% 1 1	300
	21st to end	Day	34% 24% 28% 11% 2	249
March	1st to 10th	Day	25% 22% 35% 13% 4	300
	11th to 20th	Day	24% 20% 33% 16% 6%	423
	21st to end	Day	26% 18% 33% 16% 7%	550
April	1st to 10th	Day	22% 19% 27% 22% 9% 1	500
	11th to 20th	Day	18% 17% 30% 23% 10% 2	492
	21st to end	Day	19% 18% 28% 21% 11% 3	500
May	1st to 10th	Day	20% 14% 28% 22% 12% 4	503
	11th to 20th	Day	15% 12% 25% 27% 14% 7%	527
	21st to end	Day	15% 7% 21% 28% 17% 12%	573
June	1st to 10th	Day	10% 6% 22% 24% 23% 13%	530
	11th to 20th	Day	5% 4 18% 29% 29% 15%	624
	21st to end	Day	5% 4 20% 29% 26% 16%	730
July	1st to 10th	Day	8% 3 12% 31% 26% 19%	697
	11th to 20th	Day	9% 4 11% 25% 30% 21%	524
	21st to end	Day	9% 3 12% 28% 30% 17%	532
August	1st to 10th	Day	10% 3 13% 25% 33% 16%	486
	11th to 20th	Day	9% 3 15% 31% 31% 11%	479
	21st to end	Day	13% 2 8% 23% 35% 19%	539
September	1st to 10th	Day	12% 2 13% 26% 32% 14%	490
	11th to 20th	Day	13% 5% 11% 25% 31% 16%	490
	21st to end	Day	15% 6% 16% 29% 26% 8%	490
October	1st to 10th	Day	12% 5% 21% 28% 27% 8%	490
	11th to 20th	Day	13% 13% 28% 25% 16% 4	486
	21st to end	Day	23% 14% 26% 27% 8% 2	330
November	1st to 10th	Day	18% 9% 34% 27% 10% 2	300
	11th to 20th	Day	17% 14% 38% 25% 5%	300
	21st to end	Day	20% 21% 28% 17% 12% 2	300
December	1st to 10th	Day	28% 20% 31% 18% 3	300
	11th to 20th	Day	23% 22% 29% 16% 9% 1	300
	21st to end	Day	24% 26% 29% 18% 4	330
January	1st to 10th	Night	24% 17% 32% 24% 4	800
	11th to 20th	Night	26% 20% 31% 19% 4	800
	21st to end	Night	21% 16% 37% 23% 3	880
February	1st to 10th	Night	25% 14% 33% 24% 4	800
	11th to 20th	Night	30% 16% 31% 21% 2	783
	21st to end	Night	30% 16% 33% 19% 2	660
March	1st to 10th	Night	22% 16% 33% 25% 5%	800
	11th to 20th	Night	22% 16% 34% 21% 7% 1	800
	21st to end	Night	19% 15% 33% 26% 7%	800
April	1st to 10th	Night	16% 13% 34% 29% 8%	600
	11th to 20th	Night	18% 11% 32% 30% 9% 1	593
	21st to end	Night	16% 9% 32% 31% 11% 2	600
May	1st to 10th	Night	14% 8% 32% 28% 18% 1	600
	11th to 20th	Night	12% 6% 24% 35% 18% 5%	591
	21st to end	Night	8% 3 20% 38% 26% 5%	650
June	1st to 10th	Night	8% 4 18% 37% 29% 5%	600
	11th to 20th	Night	4 2 13% 39% 35% 7%	600
	21st to end	Night	5% 1 13% 36% 37% 8%	600
July	1st to 10th	Night	10% 2 9% 32% 39% 9%	570
	11th to 20th	Night	6% 3 10% 29% 42% 10%	552
	21st to end	Night	8% 1 10% 30% 41% 9%	624
August	1st to 10th	Night	8% 2 5% 31% 46% 9%	567
	11th to 20th	Night	8% 2 10% 37% 39% 4	564
	21st to end	Night	9% 2 8% 32% 41% 9%	627
September	1st to 10th	Night	10% 3 11% 32% 38% 6%	598
	11th to 20th	Night	12% 4 14% 29% 36% 5%	760
	21st to end	Night	13% 2 16% 31% 35% 3	760
October	1st to 10th	Night	10% 6% 17% 31% 31% 5%	760
	11th to 20th	Night	18% 7% 24% 33% 17% 1	760
	21st to end	Night	18% 9% 26% 30% 16% 2	836
November	1st to 10th	Night	15% 8% 21% 36% 17% 2	780
	11th to 20th	Night	16% 12% 33% 28% 12% 1	800
	21st to end	Night	19% 13% 30% 28% 11% 1	800
December	1st to 10th	Night	25% 14% 31% 25% 5%	800
	11th to 20th	Night	23% 12% 30% 28% 6% 1	800
	21st to end	Night	26% 16% 29% 24% 5%	880

Page generated at 2025-07-03 00:30:15. Version ac07

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