Lebanon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lebanon clear sky chart from 2005-11-06 to 2025-05-26.

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	20% 8% 2 6% 4 4 4 3 4 6% 39%	118230
	Night	24% 8% 3 7% 4 4 4 3 4 5% 35%	119870
Transparency	Day	47% 5% 11% 19% 13% 5%	117975
	Night	51% 5% 11% 18% 11% 4	119714
Seeing	Day	23% 7% 21% 28% 16% 5%	15353
	Night	27% 5% 12% 31% 23% 3	24428

By Month

Percentage Cloud Cover SW (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	42% 15% 3 8% 5% 5% 4 3 3 3 8%	3639
	11th to 20th	Day	30% 10% 2 6% 5% 6% 6% 3 5% 6% 22%	3640
	21st to end	Day	29% 7% 2 6% 4 4 4 4 5% 6% 30%	4492
February	1st to 10th	Day	30% 12% 4 8% 6% 4 4 3 6% 7% 17%	1800
	11th to 20th	Day	30% 13% 2 8% 5% 6% 5% 3 4 5% 20%	1755
	21st to end	Day	32% 13% 3 8% 5% 4 4 3 4 5% 19%	1570
March	1st to 10th	Day	21% 13% 3 8% 5% 5% 6% 5% 6% 7% 21%	4777
	11th to 20th	Day	30% 11% 3 7% 4 4 3 3 4 4 28%	5000
	21st to end	Day	26% 12% 3 9% 6% 6% 5% 4 5% 7% 15%	5572
April	1st to 10th	Day	30% 13% 3 9% 6% 4 4 3 5% 6% 18%	2400
	11th to 20th	Day	26% 11% 3 7% 5% 3 4 4 5% 5% 28%	2369
	21st to end	Day	26% 8% 2 6% 5% 5% 5% 3 6% 7% 28%	2578
May	1st to 10th	Day	23% 9% 2 6% 4 4 4 3 5% 5% 34%	4427
	11th to 20th	Day	13% 5% 2 5% 3 3 3 3 4 7% 51%	4517
	21st to end	Day	20% 7% 2 8% 5% 5% 5% 4 6% 8% 31%	4886
June	1st to 10th	Day	25% 7% 3 7% 4 3 3 4 4 5% 35%	2660
	11th to 20th	Day	20% 7% 3 6% 4 5% 4 3 5% 7% 35%	2660
	21st to end	Day	11% 4 1 4 3 2 3 3 4 6% 59%	2660
July	1st to 10th	Day	3 2 1 2 1 1 1 2 2 3 80%	4420
	11th to 20th	Day	4 2 1 2 2 2 2 2 2 3 78%	4420
	21st to end	Day	4 2 1 2 2 1 2 2 3 4 78%	4740
August	1st to 10th	Day	3 3 1 3 2 2 2 2 3 5% 73%	4091
	11th to 20th	Day	5% 3 1 4 3 3 3 3 4 7% 63%	4026
	21st to end	Day	8% 5% 2 3 2 2 3 3 4 6% 62%	4283
September	1st to 10th	Day	8% 3 1 3 2 2 2 2 3 6% 69%	2280
	11th to 20th	Day	13% 5% 2 6% 4 3 3 3 4 6% 49%	2272
	21st to end	Day	16% 6% 2 5% 3 4 3 2 4 5% 49%	2002
October	1st to 10th	Day	15% 5% 2 4 3 3 3 3 4 5% 52%	3180
	11th to 20th	Day	20% 6% 2 6% 4 5% 5% 4 6% 7% 35%	3161
	21st to end	Day	25% 8% 2 8% 5% 5% 5% 4 6% 8% 22%	3422
November	1st to 10th	Day	33% 9% 3 8% 4 3 4 3 5% 6% 21%	1679
	11th to 20th	Day	34% 8% 3 7% 5% 5% 4 3 6% 5% 19%	1600
	21st to end	Day	30% 9% 3 8% 5% 5% 4 4 5% 6% 21%	1600
December	1st to 10th	Day	23% 6% 2 6% 6% 7% 7% 5% 6% 6% 27%	2620
	11th to 20th	Day	34% 12% 4 10% 7% 6% 5% 3 5% 5% 9%	3028
	21st to end	Day	37% 15% 4 10% 7% 6% 5% 3 3 4 8%	4004
January	1st to 10th	Night	39% 15% 4 10% 5% 5% 3 2 4 4 10%	6306
	11th to 20th	Night	31% 11% 3 7% 5% 5% 5% 3 3 5% 22%	6320
	21st to end	Night	30% 9% 3 6% 4 3 3 2 3 4 33%	6470
February	1st to 10th	Night	31% 13% 3 7% 5% 5% 4 3 5% 5% 19%	2600
	11th to 20th	Night	32% 11% 3 7% 4 4 3 2 4 4 26%	2532
	21st to end	Night	33% 12% 2 6% 4 3 3 3 4 6% 23%	2059
March	1st to 10th	Night	22% 14% 4 8% 5% 5% 5% 5% 7% 6% 21%	5113
	11th to 20th	Night	27% 11% 3 6% 4 4 3 3 4 4 30%	5000
	21st to end	Night	31% 12% 4 9% 6% 5% 5% 3 4 6% 16%	5402
April	1st to 10th	Night	31% 13% 3 7% 4 4 4 3 4 4 23%	2000
	11th to 20th	Night	24% 10% 3 6% 4 4 4 3 6% 6% 31%	1979
	21st to end	Night	27% 8% 2 6% 4 4 4 4 5% 6% 31%	1819
May	1st to 10th	Night	26% 9% 3 7% 4 3 2 2 3 5% 35%	2757
	11th to 20th	Night	13% 5% 2 6% 4 3 3 2 3 5% 53%	2596
	21st to end	Night	21% 7% 2 6% 4 4 4 4 6% 8% 35%	2805
June	1st to 10th	Night	21% 7% 3 5% 4 4 3 4 5% 7% 38%	1520
	11th to 20th	Night	16% 7% 2 6% 5% 3 4 3 5% 7% 41%	1520
	21st to end	Night	10% 5% 1 4 3 2 3 2 4 4 62%	1520
July	1st to 10th	Night	4 1 1 1 1 1 2 2 2 3 81%	2540
	11th to 20th	Night	4 2 1 2 2 2 2 1 2 3 80%	2540
	21st to end	Night	5% 1 1 1 1 1 1 1 2 3 82%	2809
August	1st to 10th	Night	2 2 1 2 1 1 3 2 3 5% 77%	2848
	11th to 20th	Night	5% 3 1 4 3 3 3 3 5% 6% 64%	2812
	21st to end	Night	8% 3 1 4 3 2 2 2 3 5% 66%	3391
September	1st to 10th	Night	8% 2 1 3 2 2 3 2 3 5% 69%	1900
	11th to 20th	Night	11% 4 2 4 4 4 3 4 5% 6% 55%	1905
	21st to end	Night	14% 5% 2 5% 3 3 4 2 5% 6% 53%	2177
October	1st to 10th	Night	14% 4 2 5% 3 3 3 2 3 5% 56%	3800
	11th to 20th	Night	16% 6% 2 6% 4 4 5% 4 6% 8% 42%	3777
	21st to end	Night	25% 10% 3 8% 5% 3 4 3 5% 5% 28%	4145
November	1st to 10th	Night	31% 8% 2 7% 5% 4 5% 3 4 7% 24%	2620
	11th to 20th	Night	36% 8% 3 6% 5% 4 4 3 4 5% 21%	2800
	21st to end	Night	28% 8% 2 6% 5% 4 5% 3 4 5% 28%	2800
December	1st to 10th	Night	20% 7% 2 6% 4 5% 5% 4 5% 7% 36%	4560
	11th to 20th	Night	36% 12% 4 10% 6% 5% 4 3 3 5% 13%	5176
	21st to end	Night	35% 11% 4 12% 6% 5% 4 3 3 4 13%	6952

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	79% 5% 6% 7% 3 1	3639
	11th to 20th	Day	60% 4 10% 16% 9% 2	3640
	21st to end	Day	54% 4 7% 16% 14% 5%	4492
February	1st to 10th	Day	67% 5% 11% 11% 6%	1800
	11th to 20th	Day	67% 6% 10% 9% 5% 2	1764
	21st to end	Day	69% 4 8% 11% 6% 2	1570
March	1st to 10th	Day	60% 5% 13% 17% 4	4777
	11th to 20th	Day	61% 5% 7% 19% 7% 1	5000
	21st to end	Day	68% 7% 13% 9% 3	5572
April	1st to 10th	Day	69% 5% 11% 11% 4	2400
	11th to 20th	Day	60% 5% 11% 14% 8% 2	2372
	21st to end	Day	56% 6% 14% 14% 7% 1	2578
May	1st to 10th	Day	52% 6% 12% 19% 11%	4427
	11th to 20th	Day	34% 5% 16% 32% 12% 1	4520
	21st to end	Day	51% 8% 22% 16% 2	4887
June	1st to 10th	Day	52% 6% 15% 21% 6%	2660
	11th to 20th	Day	50% 5% 18% 21% 6%	2660
	21st to end	Day	29% 4 17% 34% 13% 4	2660
July	1st to 10th	Day	12% 2 8% 18% 27% 33%	4351
	11th to 20th	Day	14% 2 5% 18% 35% 26%	4345
	21st to end	Day	13% 2 8% 28% 38% 11%	4590
August	1st to 10th	Day	15% 3 8% 31% 32% 11%	4076
	11th to 20th	Day	22% 2 16% 38% 17% 4	4065
	21st to end	Day	24% 3 14% 26% 25% 8%	4282
September	1st to 10th	Day	19% 2 10% 33% 22% 14%	2280
	11th to 20th	Day	36% 5% 13% 23% 16% 7%	2272
	21st to end	Day	37% 4 12% 23% 16% 7%	2002
October	1st to 10th	Day	35% 3 8% 21% 24% 8%	3180
	11th to 20th	Day	46% 5% 17% 20% 11% 2	3161
	21st to end	Day	57% 5% 10% 15% 11% 1	3422
November	1st to 10th	Day	65% 5% 11% 14% 5%	1679
	11th to 20th	Day	65% 6% 10% 10% 6% 2	1600
	21st to end	Day	62% 6% 9% 8% 13% 2	1600
December	1st to 10th	Day	50% 4 12% 16% 16% 1	2620
	11th to 20th	Day	72% 7% 8% 10% 2	3028
	21st to end	Day	75% 7% 8% 8% 2	4004
January	1st to 10th	Night	77% 5% 7% 6% 4 1	6306
	11th to 20th	Night	63% 4 9% 16% 6% 2	6320
	21st to end	Night	56% 3 5% 15% 15% 6%	6470
February	1st to 10th	Night	67% 5% 10% 11% 6% 1	2600
	11th to 20th	Night	63% 5% 12% 11% 7% 2	2534
	21st to end	Night	63% 5% 10% 13% 7% 2	2059
March	1st to 10th	Night	62% 5% 15% 12% 6% 1	5113
	11th to 20th	Night	59% 5% 11% 16% 9% 1	5000
	21st to end	Night	70% 6% 14% 9% 1	5402
April	1st to 10th	Night	66% 4 13% 12% 5%	2000
	11th to 20th	Night	56% 7% 14% 14% 6% 4	1979
	21st to end	Night	56% 6% 14% 16% 6% 3	1819
May	1st to 10th	Night	54% 5% 10% 20% 9% 2	2757
	11th to 20th	Night	36% 5% 13% 35% 10% 2	2596
	21st to end	Night	48% 8% 26% 16% 2	2805
June	1st to 10th	Night	46% 8% 15% 26% 5%	1520
	11th to 20th	Night	44% 5% 19% 24% 8%	1520
	21st to end	Night	28% 4 17% 34% 13% 4	1520
July	1st to 10th	Night	12% 2 7% 20% 25% 33%	2500
	11th to 20th	Night	13% 2 6% 18% 32% 29%	2492
	21st to end	Night	11% 1 9% 30% 39% 10%	2721
August	1st to 10th	Night	12% 3 10% 36% 28% 11%	2839
	11th to 20th	Night	22% 2 20% 37% 15% 4	2839
	21st to end	Night	23% 3 13% 29% 26% 6%	3391
September	1st to 10th	Night	20% 3 9% 32% 23% 13%	1900
	11th to 20th	Night	30% 6% 13% 29% 13% 10%	1905
	21st to end	Night	34% 4 12% 24% 17% 9%	2177
October	1st to 10th	Night	32% 3 7% 27% 27% 4	3800
	11th to 20th	Night	40% 5% 22% 20% 11% 2	3777
	21st to end	Night	59% 4 9% 16% 10% 2	4145
November	1st to 10th	Night	61% 6% 10% 13% 9% 1	2620
	11th to 20th	Night	66% 5% 9% 9% 8% 3	2800
	21st to end	Night	57% 6% 9% 12% 11% 4	2800
December	1st to 10th	Night	44% 4 11% 25% 16% 1	4560
	11th to 20th	Night	73% 5% 9% 8% 4	5176
	21st to end	Night	70% 10% 10% 8% 2 1	6952

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	51% 8% 12% 17% 12% 3	200
	11th to 20th	Day	42% 5% 13% 22% 13% 7%	200
	21st to end	Day	33% 7% 17% 19% 18% 6%	435
February	1st to 10th	Day	37% 8% 16% 25% 11% 3	400
	11th to 20th	Day	37% 7% 22% 22% 9% 3	395
	21st to end	Day	36% 12% 18% 20% 12% 2	374
March	1st to 10th	Day	34% 9% 23% 23% 8% 2	500
	11th to 20th	Day	34% 7% 20% 24% 10% 4	500
	21st to end	Day	34% 11% 24% 20% 9% 1	550
April	1st to 10th	Day	36% 9% 22% 21% 10% 3	500
	11th to 20th	Day	29% 11% 24% 20% 12% 4	492
	21st to end	Day	29% 10% 23% 24% 11% 3	500
May	1st to 10th	Day	21% 11% 23% 27% 13% 4	503
	11th to 20th	Day	27% 9% 19% 24% 16% 6%	528
	21st to end	Day	19% 9% 20% 27% 17% 7%	550
June	1st to 10th	Day	23% 7% 21% 28% 17% 4	490
	11th to 20th	Day	19% 10% 28% 27% 14% 2	490
	21st to end	Day	8% 5% 22% 42% 16% 6%	490
July	1st to 10th	Day	6% 5% 21% 41% 22% 5%	486
	11th to 20th	Day	3 5% 26% 39% 20% 7%	484
	21st to end	Day	4 3 21% 41% 23% 8%	531
August	1st to 10th	Day	3 1 20% 43% 25% 7%	487
	11th to 20th	Day	3 4 16% 42% 25% 10%	477
	21st to end	Day	7% 5% 26% 33% 23% 7%	539
September	1st to 10th	Day	8% 5% 23% 36% 22% 6%	490
	11th to 20th	Day	15% 5% 19% 30% 25% 6%	490
	21st to end	Day	18% 6% 20% 32% 19% 5%	490
October	1st to 10th	Day	19% 7% 21% 25% 19% 9%	490
	11th to 20th	Day	21% 7% 16% 27% 22% 7%	490
	21st to end	Day	29% 8% 21% 21% 15% 6%	525
November	1st to 10th	Day	34% 6% 19% 26% 12% 4	257
	11th to 20th	Day	33% 9% 20% 16% 15% 9%	200
	21st to end	Day	33% 6% 17% 20% 18% 7%	200
December	1st to 10th	Day	36% 7% 13% 19% 15% 12%	200
	11th to 20th	Day	46% 3 19% 19% 11% 4	200
	21st to end	Day	44% 6% 15% 18% 15% 2	220
January	1st to 10th	Night	42% 7% 11% 22% 15% 4	800
	11th to 20th	Night	38% 7% 9% 22% 20% 4	800
	21st to end	Night	34% 4 8% 32% 18% 4	880
February	1st to 10th	Night	37% 4 9% 30% 18% 2	800
	11th to 20th	Night	38% 5% 11% 29% 16% 1	784
	21st to end	Night	38% 6% 12% 25% 18%	660
March	1st to 10th	Night	34% 8% 13% 29% 15% 1	800
	11th to 20th	Night	33% 6% 13% 31% 16% 2	800
	21st to end	Night	39% 5% 14% 27% 14% 1	880
April	1st to 10th	Night	35% 7% 10% 28% 18% 1	800
	11th to 20th	Night	27% 6% 16% 31% 18% 2	791
	21st to end	Night	30% 4 12% 32% 20% 2	619
May	1st to 10th	Night	22% 5% 15% 34% 21% 2	485
	11th to 20th	Night	21% 4 12% 30% 31% 3	394
	21st to end	Night	24% 4 11% 31% 28% 2	422
June	1st to 10th	Night	21% 7% 11% 37% 23% 1	380
	11th to 20th	Night	19% 3 18% 39% 19% 1	380
	21st to end	Night	11% 3 14% 42% 30% 1	380
July	1st to 10th	Night	7% 2 13% 46% 31% 1	370
	11th to 20th	Night	6% 4 21% 42% 26% 1	368
	21st to end	Night	4 2 14% 46% 33% 2	440
August	1st to 10th	Night	4 1 7% 36% 45% 7%	567
	11th to 20th	Night	6% 1 5% 35% 47% 5%	564
	21st to end	Night	8% 3 14% 37% 33% 5%	768
September	1st to 10th	Night	8% 2 14% 36% 37% 3	760
	11th to 20th	Night	13% 3 8% 32% 36% 7%	760
	21st to end	Night	15% 4 11% 34% 32% 4	760
October	1st to 10th	Night	18% 3 11% 33% 29% 5%	760
	11th to 20th	Night	20% 4 11% 31% 28% 6%	760
	21st to end	Night	33% 4 12% 28% 19% 6%	836
November	1st to 10th	Night	34% 6% 12% 30% 17% 2	780
	11th to 20th	Night	40% 6% 11% 24% 16% 3	800
	21st to end	Night	31% 5% 10% 31% 19% 5%	800
December	1st to 10th	Night	32% 4 8% 30% 21% 5%	800
	11th to 20th	Night	41% 5% 11% 25% 16% 2	800
	21st to end	Night	45% 6% 13% 24% 11% 1	880

Page generated at 2025-05-23 06:20:57. Version ac07

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