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 2024-11-03.

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% 7% 3 7% 5% 5% 5% 4 6% 7% 39%	101548
	Night	13% 7% 3 6% 4 4 4 3 5% 7% 42%	97413
Transparency	Day	42% 7% 11% 22% 16% 3	101350
	Night	40% 6% 11% 22% 18% 4	97281
Seeing	Day	17% 11% 23% 23% 18% 8%	15025
	Night	17% 9% 24% 29% 18% 3	24516

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% 5% 11% 6% 5% 6% 4 5% 5% 28%	2836
	11th to 20th	Day	20% 10% 3 11% 5% 6% 5% 2 3 4 30%	2840
	21st to end	Day	25% 11% 6% 6% 3 3 3 3 5% 5% 30%	3389
February	1st to 10th	Day	19% 12% 4 8% 5% 3 4 2 4 5% 35%	1900
	11th to 20th	Day	19% 13% 3 8% 4 4 3 3 4 5% 33%	1848
	21st to end	Day	21% 9% 4 6% 5% 3 4 2 4 5% 35%	1570
March	1st to 10th	Day	20% 12% 3 8% 5% 4 4 3 5% 6% 30%	3120
	11th to 20th	Day	14% 7% 2 6% 4 4 4 3 4 6% 46%	3368
	21st to end	Day	13% 7% 3 6% 5% 5% 5% 4 6% 7% 39%	3968
April	1st to 10th	Day	12% 6% 3 5% 4 4 3 4 6% 6% 45%	2280
	11th to 20th	Day	14% 7% 2 6% 5% 4 4 3 5% 6% 45%	2254
	21st to end	Day	12% 8% 2 7% 5% 5% 5% 3 5% 7% 41%	2336
May	1st to 10th	Day	16% 8% 3 7% 4 5% 5% 4 5% 8% 37%	4082
	11th to 20th	Day	16% 9% 4 7% 4 5% 5% 3 6% 8% 35%	4081
	21st to end	Day	11% 7% 3 7% 5% 4 5% 4 5% 8% 41%	4476
June	1st to 10th	Day	9% 7% 2 7% 5% 5% 5% 5% 7% 9% 40%	2470
	11th to 20th	Day	4 4 2 5% 5% 6% 6% 5% 7% 10% 46%	2559
	21st to end	Day	5% 5% 2 7% 5% 5% 6% 5% 8% 12% 40%	2660
July	1st to 10th	Day	6% 5% 2 7% 6% 6% 7% 6% 9% 10% 36%	4440
	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% 6% 2 6% 4 3 4 3 4 6% 46%	1881
November	1st to 10th	Day	13% 5% 2 3 2 3 4 3 4 6% 57%	1690
	11th to 20th	Day	13% 7% 2 5% 4 3 3 3 5% 7% 49%	1710
	21st to end	Day	15% 7% 3 6% 3 3 4 4 5% 5% 44%	1710
December	1st to 10th	Day	20% 10% 4 7% 5% 4 3 3 5% 5% 34%	1710
	11th to 20th	Day	16% 10% 3 8% 5% 4 5% 4 4 5% 36%	2153
	21st to end	Day	17% 11% 4 8% 5% 4 5% 3 5% 7% 30%	3124
January	1st to 10th	Night	17% 11% 4 7% 4 3 4 3 4 6% 36%	4109
	11th to 20th	Night	20% 10% 4 8% 5% 4 3 3 4 4 35%	4120
	21st to end	Night	21% 13% 4 7% 4 3 3 3 4 5% 35%	4263
February	1st to 10th	Night	20% 10% 3 7% 4 4 3 3 5% 6% 35%	2280
	11th to 20th	Night	22% 10% 3 6% 5% 4 4 2 4 4 36%	2218
	21st to end	Night	23% 10% 2 6% 5% 4 3 3 6% 5% 33%	1884
March	1st to 10th	Night	23% 10% 3 7% 5% 4 4 4 4 6% 31%	3733
	11th to 20th	Night	13% 7% 2 5% 3 4 4 3 5% 6% 48%	3590
	21st to end	Night	14% 8% 2 7% 4 4 5% 4 5% 5% 41%	3690
April	1st to 10th	Night	12% 4 2 6% 4 4 4 3 6% 8% 47%	1900
	11th to 20th	Night	15% 7% 2 4 3 3 3 3 5% 7% 48%	1875
	21st to end	Night	13% 6% 2 6% 4 4 4 4 5% 7% 46%	1843
May	1st to 10th	Night	13% 7% 3 7% 4 4 4 3 5% 7% 41%	2813
	11th to 20th	Night	12% 8% 3 7% 5% 4 4 4 5% 8% 39%	2812
	21st to end	Night	6% 5% 2 7% 5% 6% 6% 4 7% 10% 43%	3079
June	1st to 10th	Night	6% 6% 3 7% 5% 5% 5% 4 6% 9% 43%	1710
	11th to 20th	Night	3 3 1 5% 4 4 4 4 8% 10% 54%	1611
	21st to end	Night	5% 4 1 6% 5% 4 5% 5% 6% 11% 48%	1520
July	1st to 10th	Night	7% 5% 2 6% 6% 5% 6% 6% 8% 12% 39%	2530
	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% 4 3 3 3 4 6% 49%	2717
November	1st to 10th	Night	12% 5% 2 6% 4 3 3 3 4 5% 54%	2433
	11th to 20th	Night	12% 7% 2 5% 3 3 3 2 5% 7% 50%	2470
	21st to end	Night	16% 7% 3 5% 4 3 4 3 5% 5% 45%	2470
December	1st to 10th	Night	20% 10% 3 6% 4 3 4 3 5% 5% 34%	2470
	11th to 20th	Night	16% 8% 3 6% 4 4 3 3 4 5% 44%	3042
	21st to end	Night	16% 11% 4 9% 6% 5% 5% 4 5% 6% 29%	4532

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	56% 5% 8% 18% 12% 2	2837
	11th to 20th	Day	58% 4 7% 15% 15% 1	2840
	21st to end	Day	56% 4 8% 20% 11% 1	3389
February	1st to 10th	Day	53% 5% 7% 18% 15% 2	1900
	11th to 20th	Day	54% 4 7% 18% 14% 3	1858
	21st to end	Day	52% 4 8% 15% 16% 5%	1570
March	1st to 10th	Day	54% 6% 8% 13% 13% 8%	3120
	11th to 20th	Day	39% 5% 9% 24% 17% 6%	3368
	21st to end	Day	42% 7% 10% 25% 15% 1	3968
April	1st to 10th	Day	38% 7% 10% 23% 19% 4	2280
	11th to 20th	Day	39% 6% 7% 20% 22% 5%	2254
	21st to end	Day	41% 6% 9% 25% 16% 2	2336
May	1st to 10th	Day	45% 8% 11% 22% 13% 2	4120
	11th to 20th	Day	45% 9% 11% 23% 11%	4085
	21st to end	Day	40% 8% 11% 21% 19% 1	4489
June	1st to 10th	Day	37% 11% 12% 22% 16% 2	2470
	11th to 20th	Day	30% 10% 17% 23% 18% 3	2559
	21st to end	Day	34% 11% 17% 19% 16% 4	2660
July	1st to 10th	Day	37% 11% 19% 23% 8% 2	4371
	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	31% 6% 7% 22% 28% 6%	2090
	11th to 20th	Day	32% 4 9% 21% 26% 9%	2081
	21st to end	Day	39% 5% 7% 20% 24% 6%	1881
November	1st to 10th	Day	29% 6% 9% 22% 29% 5%	1690
	11th to 20th	Day	36% 4 6% 23% 25% 6%	1710
	21st to end	Day	41% 5% 6% 23% 20% 4	1710
December	1st to 10th	Day	52% 5% 6% 21% 14% 3	1710
	11th to 20th	Day	50% 5% 10% 18% 16% 2	2150
	21st to end	Day	52% 6% 11% 19% 9% 2	3124
January	1st to 10th	Night	48% 4 8% 22% 16% 2	4109
	11th to 20th	Night	51% 6% 7% 15% 16% 5%	4120
	21st to end	Night	53% 4 8% 20% 14% 2	4263
February	1st to 10th	Night	51% 4 10% 17% 16% 1	2280
	11th to 20th	Night	54% 3 7% 17% 15% 5%	2219
	21st to end	Night	52% 5% 8% 14% 15% 5%	1884
March	1st to 10th	Night	53% 6% 9% 11% 15% 6%	3733
	11th to 20th	Night	38% 5% 7% 24% 16% 11%	3590
	21st to end	Night	44% 5% 9% 23% 17% 1	3690
April	1st to 10th	Night	35% 6% 12% 23% 21% 3	1900
	11th to 20th	Night	35% 5% 9% 20% 23% 8%	1875
	21st to end	Night	37% 6% 10% 26% 18% 2	1843
May	1st to 10th	Night	41% 8% 12% 25% 13% 1	2840
	11th to 20th	Night	42% 9% 13% 20% 16% 1	2813
	21st to end	Night	33% 10% 14% 23% 18% 1	3087
June	1st to 10th	Night	37% 7% 12% 26% 15% 3	1710
	11th to 20th	Night	22% 8% 18% 32% 17% 3	1611
	21st to end	Night	28% 10% 17% 26% 15% 4	1520
July	1st to 10th	Night	34% 10% 21% 25% 9% 2	2490
	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	26% 6% 8% 22% 28% 10%	2090
	11th to 20th	Night	35% 5% 7% 20% 23% 9%	2093
	21st to end	Night	36% 4 6% 21% 27% 6%	2717
November	1st to 10th	Night	34% 4 8% 21% 26% 7%	2433
	11th to 20th	Night	34% 4 8% 20% 27% 8%	2470
	21st to end	Night	41% 4 7% 23% 20% 5%	2470
December	1st to 10th	Night	50% 5% 9% 18% 15% 3	2470
	11th to 20th	Night	43% 4 7% 20% 22% 3	3044
	21st to end	Night	54% 5% 10% 17% 13% 1	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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	24% 24% 34% 11% 6%	270
	11th to 20th	Day	30% 28% 26% 11% 3 1	270
	21st to end	Day	26% 25% 36% 10% 3	297
February	1st to 10th	Day	32% 20% 33% 13% 2 1	270
	11th to 20th	Day	37% 24% 29% 8% 1 1	270
	21st to end	Day	38% 25% 26% 9% 1	225
March	1st to 10th	Day	26% 21% 36% 14% 4	270
	11th to 20th	Day	25% 19% 33% 16% 7%	387
	21st to end	Day	26% 18% 32% 16% 8%	506
April	1st to 10th	Day	22% 17% 27% 23% 10% 1	460
	11th to 20th	Day	19% 16% 30% 23% 10% 2	452
	21st to end	Day	18% 18% 29% 21% 11% 3	460
May	1st to 10th	Day	18% 14% 28% 23% 13% 4	463
	11th to 20th	Day	16% 10% 25% 27% 15% 7%	487
	21st to end	Day	13% 6% 20% 28% 19% 13%	529
June	1st to 10th	Day	10% 7% 22% 23% 24% 14%	490
	11th to 20th	Day	5% 4 17% 30% 29% 16%	579
	21st to end	Day	5% 4 21% 31% 24% 14%	680
July	1st to 10th	Day	8% 4 12% 31% 26% 18%	671
	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% 32% 28% 10% 3	276
	11th to 20th	Day	16% 14% 40% 26% 5%	270
	21st to end	Day	19% 21% 28% 17% 12% 2	270
December	1st to 10th	Day	29% 20% 29% 18% 3	270
	11th to 20th	Day	22% 22% 30% 16% 10% 1	270
	21st to end	Day	24% 26% 31% 16% 3	297
January	1st to 10th	Night	24% 17% 32% 23% 4	760
	11th to 20th	Night	27% 21% 30% 19% 4	760
	21st to end	Night	22% 16% 37% 23% 3	836
February	1st to 10th	Night	25% 14% 34% 23% 4	760
	11th to 20th	Night	30% 15% 31% 21% 2	743
	21st to end	Night	31% 17% 33% 18% 2	628
March	1st to 10th	Night	22% 16% 33% 25% 5%	760
	11th to 20th	Night	22% 16% 34% 21% 7% 1	760
	21st to end	Night	19% 14% 32% 26% 8%	760
April	1st to 10th	Night	15% 13% 34% 29% 8%	570
	11th to 20th	Night	18% 11% 32% 29% 9% 1	563
	21st to end	Night	16% 9% 32% 31% 11% 2	570
May	1st to 10th	Night	13% 8% 32% 28% 19% 1	570
	11th to 20th	Night	12% 6% 24% 35% 19% 5%	561
	21st to end	Night	7% 2 19% 39% 27% 6%	617
June	1st to 10th	Night	8% 4 18% 36% 30% 5%	570
	11th to 20th	Night	4 2 12% 39% 35% 7%	570
	21st to end	Night	5% 1 14% 38% 35% 8%	570
July	1st to 10th	Night	10% 2 10% 32% 38% 9%	555
	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% 7% 21% 37% 17% 2	749
	11th to 20th	Night	15% 12% 33% 28% 12% 1	760
	21st to end	Night	19% 12% 29% 28% 11% 1	760
December	1st to 10th	Night	26% 13% 31% 25% 5%	760
	11th to 20th	Night	23% 12% 30% 29% 7% 1	760
	21st to end	Night	26% 16% 29% 24% 5%	836

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