Memphis
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Memphis clear sky chart from 2005-11-06 to 2025-09-04.

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% 6% 2 6% 4 4 4 4 6% 7% 43%	125520
	Night	14% 6% 2 6% 4 3 4 3 5% 7% 48%	123379
Transparency	Day	39% 5% 10% 24% 18% 4	129157
	Night	36% 4 10% 23% 20% 6%	127820
Seeing	Day	15% 8% 22% 25% 20% 9%	16473
	Night	15% 7% 25% 31% 19% 3	26175

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	16% 10% 4 10% 3 2 2 2 2 5% 43%	3819
	11th to 20th	Day	16% 6% 2 8% 4 3 3 2 3 5% 48%	4080
	21st to end	Day	19% 9% 2 6% 4 2 3 2 4 4 46%	4488
February	1st to 10th	Day	21% 8% 4 7% 4 4 3 2 4 5% 38%	1931
	11th to 20th	Day	20% 8% 4 7% 4 3 4 2 4 5% 38%	1948
	21st to end	Day	24% 8% 3 6% 4 3 3 3 4 5% 38%	1650
March	1st to 10th	Day	17% 12% 3 9% 5% 4 3 3 4 5% 35%	4544
	11th to 20th	Day	13% 6% 2 6% 4 4 4 3 4 5% 48%	4980
	21st to end	Day	13% 8% 3 7% 5% 5% 4 4 5% 6% 42%	5780
April	1st to 10th	Day	13% 6% 2 6% 4 4 4 3 6% 7% 44%	2400
	11th to 20th	Day	15% 6% 2 5% 4 3 4 3 5% 7% 45%	2374
	21st to end	Day	15% 6% 3 6% 5% 4 4 4 6% 7% 41%	2400
May	1st to 10th	Day	16% 7% 3 7% 5% 5% 5% 5% 6% 8% 34%	5405
	11th to 20th	Day	14% 7% 2 7% 5% 5% 5% 5% 7% 10% 34%	5711
	21st to end	Day	17% 7% 3 7% 5% 4 5% 4 6% 9% 34%	6789
June	1st to 10th	Day	8% 5% 2 7% 4 4 6% 5% 8% 9% 43%	2800
	11th to 20th	Day	5% 4 1 6% 5% 4 6% 5% 8% 10% 46%	2800
	21st to end	Day	5% 3 1 5% 5% 5% 5% 5% 8% 10% 49%	2800
July	1st to 10th	Day	7% 5% 2 6% 6% 6% 6% 5% 8% 10% 40%	6360
	11th to 20th	Day	6% 4 2 6% 5% 5% 6% 6% 9% 12% 38%	6066
	21st to end	Day	11% 5% 2 7% 5% 5% 6% 5% 8% 10% 36%	6422
August	1st to 10th	Day	4 2 1 4 3 4 4 4 7% 9% 60%	3947
	11th to 20th	Day	7% 3 2 6% 4 5% 5% 5% 7% 9% 48%	3849
	21st to end	Day	6% 4 2 5% 4 4 4 4 6% 8% 53%	4312
September	1st to 10th	Day	9% 4 2 6% 5% 5% 5% 5% 5% 9% 44%	2316
	11th to 20th	Day	12% 5% 2 6% 4 4 4 4 6% 8% 45%	2228
	21st to end	Day	12% 5% 1 5% 3 3 3 3 4 6% 55%	2090
October	1st to 10th	Day	7% 4 2 4 4 4 4 2 4 6% 59%	1961
	11th to 20th	Day	12% 5% 2 3 2 3 3 3 5% 6% 56%	1900
	21st to end	Day	18% 6% 2 3 2 3 3 3 3 4 53%	2090
November	1st to 10th	Day	14% 6% 2 4 2 3 2 2 4 5% 57%	1819
	11th to 20th	Day	13% 5% 2 5% 4 3 3 3 4 6% 53%	1800
	21st to end	Day	19% 7% 2 6% 4 2 4 3 4 6% 44%	1800
December	1st to 10th	Day	17% 10% 3 5% 3 3 3 2 3 5% 47%	2871
	11th to 20th	Day	20% 9% 3 6% 4 3 3 3 4 5% 41%	3008
	21st to end	Day	16% 10% 3 8% 4 4 4 4 5% 6% 35%	3982
January	1st to 10th	Night	18% 8% 3 7% 4 3 3 2 4 4 44%	6141
	11th to 20th	Night	16% 7% 3 6% 2 3 3 2 3 4 51%	5900
	21st to end	Night	21% 8% 2 6% 3 2 3 2 3 5% 45%	6490
February	1st to 10th	Night	22% 7% 3 6% 4 3 3 2 4 5% 40%	2466
	11th to 20th	Night	20% 8% 3 5% 4 3 3 3 3 5% 42%	2338
	21st to end	Night	19% 8% 3 6% 4 3 3 3 3 5% 42%	1980
March	1st to 10th	Night	18% 8% 2 7% 4 4 4 3 4 5% 42%	5337
	11th to 20th	Night	13% 6% 2 5% 4 3 4 3 4 6% 51%	4980
	21st to end	Night	14% 5% 2 6% 4 4 4 4 5% 7% 45%	5147
April	1st to 10th	Night	12% 6% 2 5% 4 4 5% 3 5% 7% 48%	2000
	11th to 20th	Night	13% 5% 2 5% 3 3 4 2 4 6% 51%	1975
	21st to end	Night	12% 6% 3 6% 4 4 4 3 5% 6% 49%	2000
May	1st to 10th	Night	19% 8% 3 7% 3 3 4 3 5% 7% 38%	4490
	11th to 20th	Night	17% 9% 3 8% 4 4 4 3 5% 6% 36%	4180
	21st to end	Night	14% 7% 2 7% 5% 5% 5% 4 6% 8% 37%	4077
June	1st to 10th	Night	8% 4 2 5% 4 5% 5% 4 7% 10% 47%	1600
	11th to 20th	Night	3 3 1 4 3 3 4 4 7% 10% 59%	1600
	21st to end	Night	3 3 1 3 4 4 4 6% 7% 11% 55%	1600
July	1st to 10th	Night	6% 3 2 5% 5% 4 5% 4 7% 12% 48%	3618
	11th to 20th	Night	5% 3 2 4 3 4 5% 4 6% 13% 51%	3892
	21st to end	Night	10% 5% 2 6% 4 4 4 4 6% 12% 43%	4449
August	1st to 10th	Night	2 1 1 3 2 3 3 3 4 7% 70%	3203
	11th to 20th	Night	4 3 2 4 3 4 5% 4 7% 11% 55%	3200
	21st to end	Night	4 3 1 5% 3 4 4 4 6% 8% 58%	3586
September	1st to 10th	Night	8% 4 2 6% 3 3 4 3 5% 6% 53%	1930
	11th to 20th	Night	10% 6% 2 5% 3 3 4 5% 5% 6% 51%	1932
	21st to end	Night	10% 4 2 5% 4 3 3 3 3 6% 57%	2090
October	1st to 10th	Night	6% 3 2 5% 2 3 3 3 5% 7% 62%	2215
	11th to 20th	Night	10% 4 2 5% 3 2 3 2 4 6% 59%	2280
	21st to end	Night	17% 5% 2 4 3 3 3 3 3 4 54%	2508
November	1st to 10th	Night	13% 4 2 4 4 4 3 3 4 6% 54%	2474
	11th to 20th	Night	11% 5% 2 5% 3 3 4 3 4 6% 54%	2600
	21st to end	Night	14% 5% 2 5% 3 4 4 3 4 6% 50%	2600
December	1st to 10th	Night	18% 7% 2 5% 3 2 2 2 3 5% 50%	4306
	11th to 20th	Night	20% 7% 2 5% 4 3 3 3 4 4 44%	5199
	21st to end	Night	19% 7% 2 7% 5% 5% 4 3 4 5% 38%	6996

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	47% 2 9% 24% 16% 2	3820
	11th to 20th	Day	40% 4 6% 27% 22% 1	4080
	21st to end	Day	44% 2 5% 18% 25% 6%	4488
February	1st to 10th	Day	50% 4 7% 22% 15% 2	1931
	11th to 20th	Day	50% 5% 7% 17% 17% 5%	1958
	21st to end	Day	50% 4 8% 15% 18% 6%	1650
March	1st to 10th	Day	53% 4 5% 16% 13% 9%	4544
	11th to 20th	Day	39% 4 6% 20% 22% 9%	4980
	21st to end	Day	44% 4 8% 24% 19% 1	5782
April	1st to 10th	Day	39% 6% 9% 23% 20% 2	2400
	11th to 20th	Day	39% 5% 9% 23% 19% 6%	2374
	21st to end	Day	42% 5% 10% 25% 17% 2	2400
May	1st to 10th	Day	47% 6% 12% 22% 11% 1	5440
	11th to 20th	Day	44% 8% 17% 19% 10% 1	5715
	21st to end	Day	45% 8% 11% 23% 11% 2	6803
June	1st to 10th	Day	34% 9% 13% 24% 19% 2	2800
	11th to 20th	Day	30% 7% 14% 28% 18% 3	2800
	21st to end	Day	28% 9% 13% 28% 19% 4	2800
July	1st to 10th	Day	39% 5% 13% 25% 16% 1	6291
	11th to 20th	Day	35% 5% 19% 32% 8% 2	5993
	21st to end	Day	42% 5% 17% 30% 6% 1	6240
August	1st to 10th	Day	20% 5% 17% 31% 23% 3	3933
	11th to 20th	Day	32% 5% 17% 27% 17% 2	3885
	21st to end	Day	30% 5% 11% 28% 24% 3	4311
September	1st to 10th	Day	35% 9% 10% 24% 16% 6%	2316
	11th to 20th	Day	37% 7% 10% 17% 24% 6%	2228
	21st to end	Day	31% 4 10% 22% 26% 7%	2090
October	1st to 10th	Day	17% 2 6% 14% 34% 26%	3260
	11th to 20th	Day	18% 3 4 22% 38% 15%	3140
	21st to end	Day	27% 2 4 27% 31% 9%	3428
November	1st to 10th	Day	31% 3 7% 25% 24% 9%	1819
	11th to 20th	Day	33% 4 8% 21% 26% 8%	1800
	21st to end	Day	43% 4 7% 19% 23% 4	1800
December	1st to 10th	Day	42% 3 6% 24% 22% 2	2871
	11th to 20th	Day	48% 2 6% 22% 18% 4	3005
	21st to end	Day	49% 4 9% 26% 12% 1	3982
January	1st to 10th	Night	45% 3 9% 21% 18% 3	6141
	11th to 20th	Night	39% 3 6% 20% 26% 5%	5900
	21st to end	Night	45% 2 6% 21% 22% 4	6490
February	1st to 10th	Night	48% 3 8% 18% 19% 3	2466
	11th to 20th	Night	46% 4 7% 21% 16% 6%	2339
	21st to end	Night	45% 4 7% 16% 21% 7%	1980
March	1st to 10th	Night	46% 4 6% 15% 19% 10%	5337
	11th to 20th	Night	35% 4 6% 22% 18% 15%	4980
	21st to end	Night	39% 4 9% 24% 21% 3	5147
April	1st to 10th	Night	35% 6% 11% 22% 21% 5%	2000
	11th to 20th	Night	34% 5% 7% 23% 24% 7%	1975
	21st to end	Night	36% 6% 10% 24% 21% 3	2000
May	1st to 10th	Night	46% 5% 13% 21% 12% 2	4520
	11th to 20th	Night	48% 7% 12% 22% 10% 1	4181
	21st to end	Night	43% 8% 10% 22% 14% 3	4085
June	1st to 10th	Night	29% 9% 14% 23% 23% 2	1600
	11th to 20th	Night	20% 7% 15% 28% 25% 5%	1600
	21st to end	Night	21% 9% 17% 28% 21% 5%	1600
July	1st to 10th	Night	29% 6% 19% 25% 19% 2	3580
	11th to 20th	Night	26% 4 21% 35% 11% 2	3846
	21st to end	Night	36% 4 19% 31% 9%	4320
August	1st to 10th	Night	14% 5% 12% 41% 26% 2	3193
	11th to 20th	Night	24% 5% 20% 30% 19% 2	3230
	21st to end	Night	24% 5% 12% 27% 28% 4	3586
September	1st to 10th	Night	30% 6% 10% 23% 22% 8%	1930
	11th to 20th	Night	32% 6% 10% 19% 27% 6%	1932
	21st to end	Night	30% 3 9% 24% 25% 9%	2090
October	1st to 10th	Night	15% 3 6% 18% 30% 28%	3696
	11th to 20th	Night	17% 3 3 16% 35% 26%	3779
	21st to end	Night	26% 2 5% 26% 25% 15%	4120
November	1st to 10th	Night	32% 4 6% 22% 26% 9%	2474
	11th to 20th	Night	30% 4 8% 21% 26% 11%	2600
	21st to end	Night	35% 4 8% 22% 25% 6%	2600
December	1st to 10th	Night	40% 2 7% 29% 20% 3	4306
	11th to 20th	Night	44% 3 6% 23% 20% 4	5201
	21st to end	Night	46% 5% 10% 22% 14% 3	6996

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	22% 18% 39% 14% 6% 1	300
	11th to 20th	Day	28% 17% 36% 15% 4	300
	21st to end	Day	22% 19% 40% 15% 3 1	330
February	1st to 10th	Day	26% 16% 38% 13% 7% 1	300
	11th to 20th	Day	35% 21% 30% 12% 3	300
	21st to end	Day	36% 19% 30% 10% 5%	249
March	1st to 10th	Day	26% 17% 33% 19% 5% 1	300
	11th to 20th	Day	26% 21% 31% 21% 2	300
	21st to end	Day	23% 18% 33% 19% 6% 1	467
April	1st to 10th	Day	19% 16% 33% 22% 8% 1	500
	11th to 20th	Day	21% 15% 32% 22% 8% 2	492
	21st to end	Day	22% 10% 31% 22% 12% 3	500
May	1st to 10th	Day	19% 13% 28% 24% 14% 2	503
	11th to 20th	Day	15% 7% 25% 25% 20% 8%	527
	21st to end	Day	12% 6% 23% 30% 20% 10%	721
June	1st to 10th	Day	10% 5% 17% 28% 26% 14%	730
	11th to 20th	Day	5% 2 16% 35% 31% 12%	730
	21st to end	Day	5% 16% 38% 28% 13%	730
July	1st to 10th	Day	7% 2 10% 30% 30% 21%	721
	11th to 20th	Day	6% 2 13% 26% 35% 18%	718
	21st to end	Day	8% 2 9% 31% 34% 17%	794
August	1st to 10th	Day	6% 2 13% 27% 37% 15%	556
	11th to 20th	Day	11% 1 10% 30% 33% 16%	519
	21st to end	Day	12% 2 8% 22% 33% 24%	583
September	1st to 10th	Day	9% 1 10% 30% 32% 17%	502
	11th to 20th	Day	10% 2 14% 22% 33% 19%	490
	21st to end	Day	16% 3 15% 31% 23% 12%	490
October	1st to 10th	Day	8% 2 20% 35% 27% 8%	361
	11th to 20th	Day	12% 8% 32% 29% 14% 5%	300
	21st to end	Day	23% 10% 29% 25% 10% 4	330
November	1st to 10th	Day	22% 7% 24% 30% 15% 3	300
	11th to 20th	Day	9% 17% 35% 27% 12% 1	300
	21st to end	Day	25% 11% 32% 17% 13% 2	300
December	1st to 10th	Day	26% 19% 28% 19% 6% 1	300
	11th to 20th	Day	28% 14% 30% 20% 7% 1	300
	21st to end	Day	27% 17% 35% 16% 5% 1	330
January	1st to 10th	Night	23% 12% 35% 26% 5%	1000
	11th to 20th	Night	23% 14% 34% 25% 3	1000
	21st to end	Night	22% 10% 38% 27% 3	1100
February	1st to 10th	Night	26% 10% 34% 25% 4	866
	11th to 20th	Night	25% 15% 34% 23% 3	783
	21st to end	Night	24% 14% 36% 23% 3	660
March	1st to 10th	Night	20% 13% 33% 29% 5%	790
	11th to 20th	Night	22% 12% 35% 26% 4 1	600
	21st to end	Night	19% 10% 33% 27% 10%	660
April	1st to 10th	Night	15% 12% 36% 28% 9%	600
	11th to 20th	Night	15% 11% 33% 29% 11% 1	593
	21st to end	Night	14% 7% 34% 34% 10% 2	600
May	1st to 10th	Night	16% 7% 27% 37% 13% 2	600
	11th to 20th	Night	15% 7% 22% 36% 17% 3	591
	21st to end	Night	7% 4 20% 39% 27% 4	650
June	1st to 10th	Night	8% 2 16% 36% 32% 7%	600
	11th to 20th	Night	4 1 12% 39% 43% 2	600
	21st to end	Night	4 1 12% 38% 40% 6%	600
July	1st to 10th	Night	3 1 10% 32% 44% 10%	585
	11th to 20th	Night	6% 1 10% 28% 43% 12%	582
	21st to end	Night	6% 1 6% 34% 42% 11%	657
August	1st to 10th	Night	5% 1 6% 33% 47% 9%	597
	11th to 20th	Night	5% 2 8% 35% 43% 7%	594
	21st to end	Night	7% 1 9% 29% 46% 9%	660
September	1st to 10th	Night	9% 2 9% 35% 41% 4	579
	11th to 20th	Night	12% 1 12% 31% 37% 7%	602
	21st to end	Night	11% 4 15% 33% 33% 4	760
October	1st to 10th	Night	7% 4 18% 34% 33% 4	760
	11th to 20th	Night	13% 6% 24% 37% 18% 2	760
	21st to end	Night	18% 7% 25% 34% 15% 1	836
November	1st to 10th	Night	14% 6% 26% 35% 18% 2	780
	11th to 20th	Night	14% 7% 32% 36% 11%	800
	21st to end	Night	16% 11% 31% 29% 12% 1	800
December	1st to 10th	Night	21% 10% 33% 30% 6%	830
	11th to 20th	Night	23% 10% 30% 32% 7%	1000
	21st to end	Night	24% 13% 31% 27% 5%	1100

Page generated at 2025-09-01 00:51:03. Version ac07

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