Aramesh
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Aramesh clear sky chart from 2005-11-06 to 2026-01-02.

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	9% 7% 3 8% 6% 6% 6% 4 6% 8% 38%	127172
	Night	8% 7% 3 8% 5% 5% 5% 4 6% 8% 41%	124201
Transparency	Day	40% 8% 12% 18% 16% 5%	130896
	Night	38% 8% 13% 19% 16% 5%	128546
Seeing	Day	18% 16% 25% 21% 14% 6%	16525
	Night	15% 13% 23% 28% 17% 3	26599

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	6% 8% 3 7% 3 3 4 3 6% 8% 49%	4065
	11th to 20th	Day	5% 7% 2 7% 4 4 4 3 4 5% 55%	4060
	21st to end	Day	8% 9% 4 8% 4 4 5% 4 5% 6% 44%	4466
February	1st to 10th	Day	8% 8% 3 8% 5% 5% 6% 4 5% 6% 41%	1910
	11th to 20th	Day	10% 9% 4 8% 6% 5% 4 3 5% 7% 40%	1948
	21st to end	Day	8% 7% 3 7% 6% 5% 6% 4 6% 6% 41%	1650
March	1st to 10th	Day	13% 8% 3 7% 5% 4 5% 4 6% 6% 41%	4791
	11th to 20th	Day	7% 8% 3 7% 4 3 4 3 5% 6% 51%	4980
	21st to end	Day	11% 9% 3 8% 4 4 4 3 5% 5% 44%	5465
April	1st to 10th	Day	8% 8% 3 7% 4 5% 5% 4 6% 8% 43%	2200
	11th to 20th	Day	11% 8% 3 6% 4 5% 4 4 6% 7% 43%	2406
	21st to end	Day	11% 7% 3 7% 5% 5% 4 3 6% 7% 43%	2600
May	1st to 10th	Day	8% 8% 3 10% 7% 6% 7% 5% 7% 8% 31%	5862
	11th to 20th	Day	11% 8% 3 10% 7% 7% 7% 5% 7% 8% 27%	5861
	21st to end	Day	9% 7% 3 8% 6% 6% 6% 5% 7% 9% 35%	6433
June	1st to 10th	Day	9% 7% 2 9% 6% 8% 7% 6% 8% 9% 29%	2600
	11th to 20th	Day	7% 7% 3 8% 8% 6% 8% 6% 8% 10% 30%	2600
	21st to end	Day	8% 5% 2 7% 7% 7% 8% 6% 8% 10% 32%	2600
July	1st to 10th	Day	6% 5% 2 8% 7% 8% 8% 6% 8% 9% 32%	5900
	11th to 20th	Day	8% 6% 3 10% 8% 8% 9% 6% 8% 10% 24%	5900
	21st to end	Day	8% 6% 3 12% 10% 9% 9% 7% 8% 9% 18%	6424
August	1st to 10th	Day	10% 7% 3 10% 7% 7% 7% 6% 8% 9% 25%	4234
	11th to 20th	Day	7% 7% 2 9% 7% 7% 7% 6% 8% 11% 29%	4174
	21st to end	Day	7% 5% 2 7% 5% 6% 6% 4 7% 9% 40%	4298
September	1st to 10th	Day	10% 7% 3 8% 7% 6% 6% 5% 6% 8% 34%	2200
	11th to 20th	Day	15% 8% 4 8% 4 5% 7% 4 5% 8% 31%	2200
	21st to end	Day	13% 7% 3 6% 5% 5% 5% 4 6% 6% 38%	2200
October	1st to 10th	Day	11% 6% 2 6% 4 5% 3 3 5% 6% 48%	2185
	11th to 20th	Day	7% 6% 2 5% 4 4 4 3 4 6% 54%	2000
	21st to end	Day	10% 7% 2 4 3 3 4 3 4 5% 55%	2200
November	1st to 10th	Day	7% 6% 2 5% 3 4 4 4 5% 6% 55%	1932
	11th to 20th	Day	7% 6% 1 5% 3 4 4 4 5% 8% 52%	1890
	21st to end	Day	8% 7% 2 6% 4 5% 3 4 6% 6% 49%	1890
December	1st to 10th	Day	6% 6% 3 7% 4 4 5% 3 6% 6% 49%	3020
	11th to 20th	Day	8% 7% 3 7% 3 5% 6% 5% 8% 9% 39%	3463
	21st to end	Day	8% 7% 4 9% 4 4 5% 3 5% 8% 43%	4565
January	1st to 10th	Night	7% 7% 3 10% 5% 5% 5% 4 6% 6% 43%	5903
	11th to 20th	Night	6% 5% 2 5% 4 4 4 5% 7% 7% 50%	5900
	21st to end	Night	6% 10% 4 8% 5% 4 4 3 4 6% 45%	6490
February	1st to 10th	Night	6% 8% 4 8% 4 5% 6% 4 7% 6% 42%	2485
	11th to 20th	Night	10% 10% 4 9% 5% 5% 4 4 5% 6% 39%	2338
	21st to end	Night	8% 7% 4 7% 6% 5% 5% 6% 6% 7% 39%	1980
March	1st to 10th	Night	11% 12% 4 8% 5% 5% 5% 4 5% 5% 36%	5061
	11th to 20th	Night	6% 6% 3 6% 4 4 4 4 6% 7% 50%	4980
	21st to end	Night	9% 8% 3 8% 5% 4 5% 4 5% 7% 43%	5467
April	1st to 10th	Night	8% 8% 2 6% 5% 4 5% 4 6% 7% 45%	2200
	11th to 20th	Night	7% 7% 2 8% 5% 5% 4 3 5% 7% 48%	1957
	21st to end	Night	9% 5% 2 6% 5% 5% 4 4 6% 7% 48%	1800
May	1st to 10th	Night	8% 7% 3 8% 5% 6% 7% 5% 8% 11% 33%	4033
	11th to 20th	Night	10% 10% 3 10% 6% 6% 6% 5% 7% 9% 28%	4032
	21st to end	Night	8% 7% 3 7% 5% 6% 5% 4 7% 9% 38%	4421
June	1st to 10th	Night	5% 5% 3 7% 6% 6% 6% 5% 10% 12% 36%	1800
	11th to 20th	Night	4 5% 2 6% 5% 5% 6% 5% 7% 12% 42%	1800
	21st to end	Night	6% 4 2 6% 4 6% 6% 5% 9% 11% 42%	1800
July	1st to 10th	Night	5% 5% 3 7% 6% 7% 7% 5% 8% 10% 35%	4058
	11th to 20th	Night	5% 5% 3 8% 9% 8% 7% 5% 8% 12% 31%	4057
	21st to end	Night	7% 7% 4 12% 9% 9% 7% 5% 7% 9% 24%	4427
August	1st to 10th	Night	8% 6% 3 9% 6% 8% 7% 5% 7% 11% 31%	2915
	11th to 20th	Night	9% 6% 2 8% 6% 7% 7% 4 9% 8% 34%	2875
	21st to end	Night	7% 4 2 6% 4 5% 5% 5% 6% 9% 48%	3561
September	1st to 10th	Night	9% 7% 3 8% 6% 5% 5% 4 8% 8% 38%	2200
	11th to 20th	Night	12% 9% 3 8% 5% 5% 5% 4 6% 8% 36%	2200
	21st to end	Night	13% 6% 3 7% 5% 4 4 3 5% 7% 45%	2200
October	1st to 10th	Night	12% 7% 2 6% 4 4 3 3 5% 6% 47%	2215
	11th to 20th	Night	9% 8% 2 7% 3 4 5% 4 5% 5% 50%	2400
	21st to end	Night	8% 7% 2 6% 3 3 4 3 4 5% 54%	2640
November	1st to 10th	Night	8% 7% 2 7% 4 4 5% 3 6% 6% 48%	2581
	11th to 20th	Night	9% 7% 2 6% 4 3 3 3 6% 7% 49%	2730
	21st to end	Night	8% 7% 3 6% 4 5% 4 5% 6% 6% 47%	2730
December	1st to 10th	Night	7% 7% 3 8% 4 5% 5% 4 6% 6% 46%	4380
	11th to 20th	Night	9% 9% 4 10% 5% 5% 5% 5% 5% 5% 38%	4952
	21st to end	Night	10% 8% 5% 8% 4 4 5% 4 6% 8% 38%	6633

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	31% 5% 6% 20% 34% 4	4066
	11th to 20th	Day	29% 6% 8% 14% 34% 9%	4060
	21st to end	Day	40% 6% 7% 17% 22% 8%	4466
February	1st to 10th	Day	42% 5% 12% 20% 16% 5%	1910
	11th to 20th	Day	43% 6% 11% 17% 18% 5%	1958
	21st to end	Day	42% 7% 9% 15% 20% 7%	1650
March	1st to 10th	Day	41% 5% 7% 14% 20% 12%	4791
	11th to 20th	Day	33% 5% 7% 14% 22% 20%	4980
	21st to end	Day	42% 6% 7% 25% 14% 6%	5465
April	1st to 10th	Day	37% 7% 12% 22% 17% 4	2200
	11th to 20th	Day	39% 7% 10% 18% 20% 6%	2406
	21st to end	Day	39% 7% 12% 26% 14% 2	2600
May	1st to 10th	Day	47% 11% 14% 18% 10% 1	5897
	11th to 20th	Day	52% 9% 13% 17% 8%	5865
	21st to end	Day	42% 10% 13% 18% 14% 2	6447
June	1st to 10th	Day	46% 13% 17% 16% 7% 1	2600
	11th to 20th	Day	43% 13% 18% 14% 11% 1	2600
	21st to end	Day	42% 12% 17% 17% 10% 2	2600
July	1st to 10th	Day	41% 14% 17% 19% 9%	5835
	11th to 20th	Day	48% 15% 22% 11% 3 1	5831
	21st to end	Day	56% 12% 16% 9% 5%	6240
August	1st to 10th	Day	50% 11% 16% 19% 3	4221
	11th to 20th	Day	43% 12% 21% 13% 8% 2	4213
	21st to end	Day	36% 9% 14% 28% 11% 1	4298
September	1st to 10th	Day	44% 11% 12% 17% 13% 3	2200
	11th to 20th	Day	49% 9% 10% 17% 14% 1	2200
	21st to end	Day	44% 8% 12% 18% 13% 5%	2200
October	1st to 10th	Day	31% 6% 7% 18% 27% 13%	3562
	11th to 20th	Day	22% 3 7% 21% 23% 24%	3240
	21st to end	Day	24% 4 7% 28% 21% 16%	3538
November	1st to 10th	Day	30% 6% 10% 19% 27% 9%	1932
	11th to 20th	Day	31% 5% 9% 22% 26% 8%	1890
	21st to end	Day	34% 6% 8% 24% 21% 6%	1890
December	1st to 10th	Day	34% 7% 7% 19% 27% 6%	3020
	11th to 20th	Day	38% 8% 11% 18% 18% 6%	3460
	21st to end	Day	38% 5% 13% 26% 15% 4	4565
January	1st to 10th	Night	36% 4 11% 21% 21% 6%	5903
	11th to 20th	Night	29% 6% 10% 15% 30% 10%	5900
	21st to end	Night	40% 5% 8% 16% 22% 10%	6490
February	1st to 10th	Night	39% 6% 13% 19% 17% 4	2485
	11th to 20th	Night	45% 5% 10% 19% 16% 5%	2339
	21st to end	Night	42% 7% 11% 17% 16% 6%	1980
March	1st to 10th	Night	46% 7% 7% 13% 21% 6%	5061
	11th to 20th	Night	30% 7% 8% 19% 21% 15%	4980
	21st to end	Night	41% 6% 11% 25% 12% 5%	5467
April	1st to 10th	Night	36% 8% 15% 22% 17% 3	2200
	11th to 20th	Night	35% 7% 11% 23% 20% 4	1957
	21st to end	Night	35% 9% 14% 27% 14% 1	1800
May	1st to 10th	Night	41% 13% 17% 23% 6% 1	4060
	11th to 20th	Night	49% 11% 18% 18% 5%	4033
	21st to end	Night	39% 11% 18% 22% 10% 1	4429
June	1st to 10th	Night	36% 17% 20% 20% 7% 1	1800
	11th to 20th	Night	31% 14% 24% 22% 8% 1	1800
	21st to end	Night	32% 13% 21% 20% 11% 2	1800
July	1st to 10th	Night	37% 14% 21% 22% 5%	4015
	11th to 20th	Night	39% 16% 28% 13% 3 1	4006
	21st to end	Night	51% 13% 19% 11% 5%	4297
August	1st to 10th	Night	42% 13% 27% 15% 4	2904
	11th to 20th	Night	42% 14% 23% 13% 7%	2902
	21st to end	Night	30% 10% 19% 30% 10% 1	3561
September	1st to 10th	Night	40% 13% 14% 20% 12% 2	2200
	11th to 20th	Night	45% 10% 12% 18% 13% 1	2200
	21st to end	Night	40% 8% 13% 22% 15% 3	2200
October	1st to 10th	Night	34% 5% 10% 18% 24% 8%	3618
	11th to 20th	Night	25% 4 7% 22% 22% 20%	3899
	21st to end	Night	28% 5% 7% 24% 22% 14%	4252
November	1st to 10th	Night	35% 6% 11% 20% 21% 7%	2581
	11th to 20th	Night	34% 6% 8% 20% 24% 9%	2730
	21st to end	Night	36% 6% 9% 23% 21% 6%	2730
December	1st to 10th	Night	36% 8% 10% 19% 23% 4	4380
	11th to 20th	Night	45% 7% 8% 17% 16% 6%	4954
	21st to end	Night	41% 5% 13% 19% 19% 2	6633

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	31% 28% 31% 9% 1	303
	11th to 20th	Day	31% 28% 26% 13% 2	300
	21st to end	Day	25% 37% 29% 8% 2	330
February	1st to 10th	Day	26% 31% 32% 10% 2	300
	11th to 20th	Day	44% 30% 20% 6% 1	300
	21st to end	Day	35% 32% 25% 6% 1	249
March	1st to 10th	Day	27% 23% 31% 13% 5%	429
	11th to 20th	Day	25% 30% 26% 15% 4 1	500
	21st to end	Day	27% 25% 30% 14% 5%	550
April	1st to 10th	Day	22% 25% 28% 16% 7% 1	500
	11th to 20th	Day	23% 22% 26% 18% 8% 2	492
	21st to end	Day	20% 17% 29% 19% 12% 3	500
May	1st to 10th	Day	17% 21% 27% 21% 9% 5%	503
	11th to 20th	Day	18% 13% 26% 24% 11% 7%	527
	21st to end	Day	17% 11% 22% 26% 16% 9%	573
June	1st to 10th	Day	12% 10% 28% 24% 17% 9%	530
	11th to 20th	Day	8% 9% 25% 24% 22% 12%	530
	21st to end	Day	8% 7% 31% 23% 19% 11%	530
July	1st to 10th	Day	8% 5% 17% 28% 27% 15%	525
	11th to 20th	Day	8% 3 14% 30% 24% 21%	524
	21st to end	Day	7% 3 14% 28% 31% 16%	576
August	1st to 10th	Day	17% 6% 21% 22% 19% 16%	526
	11th to 20th	Day	10% 6% 17% 29% 23% 15%	519
	21st to end	Day	11% 4 19% 26% 24% 16%	583
September	1st to 10th	Day	8% 4 22% 29% 25% 11%	530
	11th to 20th	Day	17% 6% 19% 25% 25% 9%	530
	21st to end	Day	19% 7% 19% 30% 20% 5%	530
October	1st to 10th	Day	17% 11% 20% 28% 17% 7%	530
	11th to 20th	Day	14% 16% 28% 25% 15% 2	530
	21st to end	Day	19% 15% 25% 27% 11% 3	583
November	1st to 10th	Day	17% 16% 33% 23% 9% 2	410
	11th to 20th	Day	21% 23% 35% 16% 5%	330
	21st to end	Day	22% 24% 33% 15% 6% 1	330
December	1st to 10th	Day	27% 31% 29% 11% 2	330
	11th to 20th	Day	23% 21% 36% 14% 5%	330
	21st to end	Day	24% 24% 35% 12% 4 1	363
January	1st to 10th	Night	20% 24% 31% 20% 5%	805
	11th to 20th	Night	19% 23% 33% 20% 5%	800
	21st to end	Night	16% 25% 34% 22% 2	880
February	1st to 10th	Night	18% 20% 33% 26% 4	800
	11th to 20th	Night	24% 25% 32% 18% 1	783
	21st to end	Night	21% 27% 32% 17% 2	660
March	1st to 10th	Night	19% 23% 32% 22% 4	800
	11th to 20th	Night	19% 22% 31% 21% 7% 1	800
	21st to end	Night	19% 21% 32% 21% 7%	880
April	1st to 10th	Night	19% 21% 30% 23% 7% 1	800
	11th to 20th	Night	15% 16% 31% 27% 10% 2	658
	21st to end	Night	12% 13% 28% 34% 12% 1	600
May	1st to 10th	Night	13% 11% 29% 29% 16% 1	600
	11th to 20th	Night	13% 8% 23% 34% 20% 3	591
	21st to end	Night	11% 6% 17% 30% 31% 6%	650
June	1st to 10th	Night	7% 4 18% 38% 29% 6%	600
	11th to 20th	Night	7% 2 19% 30% 33% 10%	600
	21st to end	Night	7% 3 14% 33% 37% 7%	600
July	1st to 10th	Night	8% 3 9% 31% 43% 6%	585
	11th to 20th	Night	8% 3 8% 27% 42% 12%	582
	21st to end	Night	7% 3 6% 30% 43% 11%	657
August	1st to 10th	Night	11% 3 7% 32% 38% 9%	597
	11th to 20th	Night	10% 3 11% 29% 38% 8%	594
	21st to end	Night	10% 3 10% 28% 38% 10%	693
September	1st to 10th	Night	11% 4 13% 31% 34% 7%	800
	11th to 20th	Night	17% 5% 12% 30% 31% 5%	800
	21st to end	Night	17% 6% 16% 32% 26% 3	800
October	1st to 10th	Night	16% 9% 19% 25% 25% 7%	800
	11th to 20th	Night	14% 12% 25% 32% 16% 2	800
	21st to end	Night	14% 14% 23% 34% 13% 3	880
November	1st to 10th	Night	15% 10% 23% 33% 16% 3	820
	11th to 20th	Night	18% 15% 24% 32% 10% 2	840
	21st to end	Night	18% 17% 23% 30% 11% 1	840
December	1st to 10th	Night	18% 20% 30% 26% 6%	840
	11th to 20th	Night	17% 15% 32% 29% 7% 1	840
	21st to end	Night	20% 18% 31% 27% 4	924

Page generated at 2025-12-30 01:14:09. Version ac07

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