Fort Mountain Scenic Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Mountain Scenic Overlook clear sky chart from 2005-11-06 to 2026-03-03.

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	15% 7% 3 6% 4 4 5% 4 6% 7% 39%	131109
	Night	15% 7% 2 6% 4 4 4 3 5% 7% 42%	130090
Transparency	Day	41% 7% 11% 20% 17% 4	134872
	Night	40% 6% 10% 20% 19% 5%	134384
Seeing	Day	21% 12% 23% 22% 15% 7%	16480
	Night	19% 10% 20% 28% 19% 3	26581

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	23% 10% 3 5% 3 3 3 3 3 4 41%	5258
	11th to 20th	Day	13% 6% 4 6% 3 2 3 2 3 4 53%	5280
	21st to end	Day	23% 13% 3 6% 3 3 3 3 4 5% 35%	6034
February	1st to 10th	Day	21% 10% 2 5% 4 3 4 3 4 6% 36%	2100
	11th to 20th	Day	24% 9% 2 6% 4 4 3 3 5% 5% 35%	2048
	21st to end	Day	24% 7% 2 6% 4 3 4 3 4 4 37%	1730
March	1st to 10th	Day	21% 8% 4 7% 4 4 4 3 5% 6% 33%	4580
	11th to 20th	Day	13% 6% 2 6% 4 3 3 3 5% 7% 49%	4980
	21st to end	Day	18% 6% 2 7% 4 4 4 3 4 6% 42%	5465
April	1st to 10th	Day	14% 6% 2 6% 5% 5% 5% 4 6% 7% 41%	2314
	11th to 20th	Day	13% 7% 3 7% 4 4 4 3 5% 6% 45%	2374
	21st to end	Day	13% 7% 2 6% 4 5% 5% 4 5% 8% 41%	2550
May	1st to 10th	Day	20% 7% 3 6% 4 5% 5% 5% 6% 7% 32%	5862
	11th to 20th	Day	17% 9% 3 9% 6% 6% 5% 4 6% 8% 26%	5861
	21st to end	Day	15% 8% 3 7% 5% 4 5% 4 6% 8% 37%	6433
June	1st to 10th	Day	12% 7% 3 7% 5% 4 6% 5% 8% 9% 35%	2600
	11th to 20th	Day	8% 4 2 6% 5% 5% 6% 6% 9% 11% 39%	2600
	21st to end	Day	7% 5% 3 5% 5% 7% 6% 5% 9% 11% 37%	2600
July	1st to 10th	Day	7% 5% 2 7% 5% 6% 7% 6% 9% 10% 36%	5900
	11th to 20th	Day	8% 6% 2 6% 5% 6% 6% 6% 9% 12% 33%	5900
	21st to end	Day	11% 8% 3 9% 7% 6% 7% 6% 9% 11% 22%	6424
August	1st to 10th	Day	5% 4 2 6% 5% 6% 7% 6% 10% 12% 38%	4234
	11th to 20th	Day	9% 5% 2 5% 5% 5% 6% 5% 8% 11% 38%	3889
	21st to end	Day	8% 4 2 6% 5% 5% 6% 5% 7% 8% 45%	4312
September	1st to 10th	Day	10% 6% 2 7% 5% 5% 6% 5% 7% 10% 37%	2240
	11th to 20th	Day	13% 7% 2 6% 4 4 5% 4 6% 8% 41%	2200
	21st to end	Day	14% 5% 2 6% 4 4 6% 4 4 7% 45%	2200
October	1st to 10th	Day	10% 6% 2 5% 4 4 4 4 5% 5% 53%	2200
	11th to 20th	Day	12% 4 2 5% 3 3 4 3 4 5% 56%	2105
	21st to end	Day	15% 6% 2 4 3 2 3 3 5% 6% 52%	2156
November	1st to 10th	Day	13% 6% 2 4 2 3 3 4 4 6% 53%	1852
	11th to 20th	Day	15% 6% 2 4 3 3 3 3 5% 6% 50%	1890
	21st to end	Day	18% 6% 3 6% 4 3 3 3 5% 6% 44%	1890
December	1st to 10th	Day	22% 7% 2 4 3 4 3 2 4 5% 45%	3020
	11th to 20th	Day	19% 12% 4 7% 4 4 4 3 4 4 36%	3463
	21st to end	Day	20% 11% 4 6% 3 3 3 3 5% 7% 35%	4565
January	1st to 10th	Night	20% 8% 2 6% 3 4 3 3 4 5% 42%	7635
	11th to 20th	Night	16% 8% 3 6% 3 3 2 2 4 5% 48%	7680
	21st to end	Night	20% 11% 3 6% 4 3 3 2 3 4 41%	8143
February	1st to 10th	Night	18% 8% 2 6% 4 4 4 3 5% 6% 42%	2520
	11th to 20th	Night	24% 8% 3 6% 3 4 4 3 4 4 36%	2458
	21st to end	Night	23% 8% 2 6% 4 5% 4 3 4 5% 35%	2076
March	1st to 10th	Night	21% 9% 3 7% 4 4 4 3 5% 7% 33%	5317
	11th to 20th	Night	14% 5% 1 5% 3 4 4 3 6% 7% 49%	4980
	21st to end	Night	15% 8% 2 7% 4 4 4 3 4 6% 43%	5467
April	1st to 10th	Night	14% 4 1 5% 4 4 4 3 6% 9% 46%	2101
	11th to 20th	Night	14% 7% 2 4 4 3 2 3 5% 7% 48%	1975
	21st to end	Night	12% 6% 2 5% 4 4 3 4 6% 7% 47%	1850
May	1st to 10th	Night	16% 8% 3 7% 5% 5% 5% 5% 7% 8% 32%	4033
	11th to 20th	Night	21% 9% 3 7% 5% 5% 5% 4 6% 7% 28%	4032
	21st to end	Night	14% 6% 3 6% 4 5% 5% 4 6% 9% 37%	4421
June	1st to 10th	Night	9% 5% 2 7% 6% 6% 5% 5% 7% 11% 37%	1800
	11th to 20th	Night	6% 5% 2 4 4 4 5% 5% 9% 12% 45%	1800
	21st to end	Night	7% 4 2 5% 6% 5% 5% 5% 8% 10% 43%	1800
July	1st to 10th	Night	8% 5% 3 8% 6% 5% 6% 4 8% 11% 35%	4058
	11th to 20th	Night	8% 6% 2 7% 5% 6% 6% 5% 8% 10% 37%	4057
	21st to end	Night	10% 8% 3 8% 6% 5% 6% 6% 8% 10% 28%	4427
August	1st to 10th	Night	6% 4 2 5% 4 5% 6% 5% 8% 12% 43%	2915
	11th to 20th	Night	9% 6% 2 5% 4 4 4 4 7% 10% 47%	3155
	21st to end	Night	7% 4 2 6% 4 4 4 4 6% 9% 50%	3586
September	1st to 10th	Night	8% 6% 2 7% 5% 5% 5% 5% 6% 8% 42%	2139
	11th to 20th	Night	11% 6% 2 6% 4 4 5% 3 6% 8% 45%	2200
	21st to end	Night	12% 6% 1 5% 3 4 4 4 5% 8% 48%	2200
October	1st to 10th	Night	10% 5% 2 4 4 4 3 3 4 5% 56%	2200
	11th to 20th	Night	13% 4 2 5% 3 3 3 3 3 5% 56%	2294
	21st to end	Night	13% 6% 2 5% 4 3 3 2 4 5% 54%	2680
November	1st to 10th	Night	13% 6% 2 4 3 3 3 2 4 5% 54%	2666
	11th to 20th	Night	14% 6% 2 5% 3 3 3 2 5% 6% 51%	2730
	21st to end	Night	18% 7% 2 5% 4 3 4 4 4 6% 45%	2730
December	1st to 10th	Night	22% 7% 2 4 2 3 3 3 5% 5% 44%	4380
	11th to 20th	Night	21% 10% 3 7% 4 3 3 3 4 5% 39%	4952
	21st to end	Night	19% 9% 4 7% 4 4 4 2 4 6% 35%	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	48% 3 6% 21% 19% 3	5259
	11th to 20th	Day	35% 4 4 15% 33% 9%	5280
	21st to end	Day	52% 2 6% 16% 17% 6%	6034
February	1st to 10th	Day	48% 4 6% 19% 19% 3	2100
	11th to 20th	Day	51% 5% 5% 19% 17% 5%	2058
	21st to end	Day	49% 5% 6% 14% 21% 6%	1730
March	1st to 10th	Day	50% 5% 8% 12% 18% 8%	4580
	11th to 20th	Day	35% 4 7% 16% 24% 14%	4980
	21st to end	Day	44% 4 7% 25% 16% 3	5465
April	1st to 10th	Day	40% 7% 12% 20% 17% 4	2314
	11th to 20th	Day	40% 5% 6% 19% 24% 5%	2374
	21st to end	Day	39% 7% 11% 26% 14% 3	2550
May	1st to 10th	Day	46% 10% 13% 19% 11% 1	5897
	11th to 20th	Day	53% 9% 13% 18% 6% 1	5865
	21st to end	Day	43% 8% 10% 22% 15% 2	6447
June	1st to 10th	Day	43% 9% 16% 21% 10% 2	2600
	11th to 20th	Day	36% 9% 19% 23% 11% 2	2600
	21st to end	Day	37% 11% 18% 20% 12% 3	2600
July	1st to 10th	Day	36% 12% 20% 23% 9% 1	5835
	11th to 20th	Day	37% 13% 29% 16% 4 1	5831
	21st to end	Day	50% 13% 17% 15% 5%	6240
August	1st to 10th	Day	33% 11% 18% 30% 9%	4221
	11th to 20th	Day	35% 9% 20% 22% 13% 2	3926
	21st to end	Day	33% 9% 13% 28% 15% 2	4311
September	1st to 10th	Day	40% 10% 14% 16% 16% 4	2240
	11th to 20th	Day	40% 8% 12% 21% 17% 1	2200
	21st to end	Day	38% 7% 13% 16% 20% 6%	2200
October	1st to 10th	Day	25% 5% 7% 15% 38% 11%	3590
	11th to 20th	Day	21% 4 5% 18% 29% 22%	3410
	21st to end	Day	28% 4 5% 26% 26% 11%	3458
November	1st to 10th	Day	32% 5% 7% 17% 30% 9%	1852
	11th to 20th	Day	35% 4 7% 21% 25% 9%	1890
	21st to end	Day	41% 4 6% 19% 25% 5%	1890
December	1st to 10th	Day	43% 4 5% 17% 26% 5%	3020
	11th to 20th	Day	51% 3 6% 17% 17% 4	3460
	21st to end	Day	47% 5% 8% 26% 13% 1	4565
January	1st to 10th	Night	45% 4 10% 19% 19% 3	7636
	11th to 20th	Night	40% 4 5% 18% 26% 8%	7680
	21st to end	Night	48% 3 4 18% 20% 7%	8143
February	1st to 10th	Night	44% 4 7% 19% 21% 5%	2520
	11th to 20th	Night	51% 4 5% 17% 17% 5%	2459
	21st to end	Night	50% 5% 6% 15% 18% 6%	2076
March	1st to 10th	Night	50% 5% 8% 14% 19% 4	5317
	11th to 20th	Night	34% 4 7% 18% 22% 14%	4980
	21st to end	Night	42% 4 8% 24% 18% 5%	5467
April	1st to 10th	Night	34% 6% 12% 20% 22% 5%	2101
	11th to 20th	Night	35% 4 8% 23% 21% 8%	1975
	21st to end	Night	36% 6% 11% 27% 18% 2	1850
May	1st to 10th	Night	46% 10% 15% 18% 11% 1	4060
	11th to 20th	Night	53% 8% 15% 16% 7%	4033
	21st to end	Night	40% 10% 13% 23% 14% 1	4429
June	1st to 10th	Night	39% 11% 17% 21% 11% 2	1800
	11th to 20th	Night	28% 10% 22% 26% 13% 2	1800
	21st to end	Night	32% 10% 20% 21% 13% 5%	1800
July	1st to 10th	Night	39% 10% 18% 24% 7%	4015
	11th to 20th	Night	38% 12% 25% 19% 5% 1	4006
	21st to end	Night	47% 12% 17% 18% 5% 1	4297
August	1st to 10th	Night	30% 10% 17% 32% 10%	2904
	11th to 20th	Night	32% 8% 17% 28% 14% 1	3184
	21st to end	Night	29% 8% 14% 25% 22% 2	3586
September	1st to 10th	Night	36% 10% 16% 18% 15% 5%	2139
	11th to 20th	Night	35% 10% 14% 22% 18% 1	2200
	21st to end	Night	34% 7% 12% 20% 19% 7%	2200
October	1st to 10th	Night	21% 4 9% 17% 36% 13%	3590
	11th to 20th	Night	20% 3 4 17% 35% 20%	3728
	21st to end	Night	24% 3 4 27% 29% 13%	4316
November	1st to 10th	Night	33% 4 8% 21% 25% 9%	2666
	11th to 20th	Night	34% 3 6% 20% 27% 10%	2730
	21st to end	Night	40% 5% 6% 20% 24% 5%	2730
December	1st to 10th	Night	42% 4 6% 18% 26% 5%	4380
	11th to 20th	Night	47% 5% 6% 15% 23% 4	4954
	21st to end	Night	48% 5% 8% 25% 12% 1	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	40% 19% 31% 8% 2	330
	11th to 20th	Day	38% 24% 27% 8% 3	330
	21st to end	Day	30% 31% 27% 9% 2	363
February	1st to 10th	Day	31% 24% 35% 9% 1	330
	11th to 20th	Day	49% 22% 23% 5% 1	330
	21st to end	Day	42% 23% 27% 7% 1	273
March	1st to 10th	Day	35% 21% 27% 14% 2	334
	11th to 20th	Day	31% 20% 26% 17% 5% 1	500
	21st to end	Day	29% 21% 28% 16% 6%	550
April	1st to 10th	Day	26% 17% 26% 19% 11% 1	500
	11th to 20th	Day	21% 17% 30% 20% 10% 1	492
	21st to end	Day	22% 12% 32% 20% 11% 3	500
May	1st to 10th	Day	22% 14% 29% 19% 11% 4	503
	11th to 20th	Day	16% 11% 26% 26% 15% 7%	527
	21st to end	Day	16% 8% 23% 25% 18% 10%	573
June	1st to 10th	Day	17% 6% 19% 27% 19% 10%	530
	11th to 20th	Day	11% 5% 16% 29% 23% 16%	530
	21st to end	Day	10% 4 18% 29% 22% 16%	530
July	1st to 10th	Day	13% 3 12% 25% 29% 18%	525
	11th to 20th	Day	12% 4 8% 28% 28% 19%	524
	21st to end	Day	13% 4 6% 27% 31% 18%	576
August	1st to 10th	Day	13% 4 15% 26% 25% 17%	526
	11th to 20th	Day	14% 6% 13% 27% 27% 14%	519
	21st to end	Day	16% 3 11% 24% 32% 14%	583
September	1st to 10th	Day	11% 3 17% 30% 28% 11%	530
	11th to 20th	Day	16% 5% 15% 28% 26% 10%	530
	21st to end	Day	16% 7% 15% 31% 26% 4	530
October	1st to 10th	Day	14% 6% 25% 31% 19% 5%	530
	11th to 20th	Day	17% 10% 27% 29% 15% 1	530
	21st to end	Day	19% 12% 28% 26% 13% 1	539
November	1st to 10th	Day	23% 16% 31% 21% 7% 2	330
	11th to 20th	Day	21% 22% 35% 18% 4	330
	21st to end	Day	24% 23% 35% 12% 5% 1	330
December	1st to 10th	Day	35% 22% 27% 13% 1 1	330
	11th to 20th	Day	34% 16% 31% 15% 4	330
	21st to end	Day	33% 23% 28% 13% 3 1	363
January	1st to 10th	Night	30% 19% 27% 20% 5%	840
	11th to 20th	Night	29% 17% 25% 22% 6%	840
	21st to end	Night	24% 18% 30% 24% 3	924
February	1st to 10th	Night	25% 16% 27% 29% 4	840
	11th to 20th	Night	30% 19% 28% 20% 3	823
	21st to end	Night	31% 16% 30% 20% 3	692
March	1st to 10th	Night	22% 16% 32% 24% 5%	809
	11th to 20th	Night	22% 18% 26% 26% 8% 1	800
	21st to end	Night	22% 15% 28% 26% 10%	880
April	1st to 10th	Night	18% 14% 27% 30% 11% 1	701
	11th to 20th	Night	19% 12% 31% 25% 12% 1	593
	21st to end	Night	17% 9% 24% 34% 15% 1	600
May	1st to 10th	Night	13% 10% 26% 32% 19% 1	600
	11th to 20th	Night	17% 5% 19% 32% 21% 5%	591
	21st to end	Night	12% 3 14% 34% 30% 7%	650
June	1st to 10th	Night	11% 4 12% 38% 31% 5%	600
	11th to 20th	Night	7% 3 12% 32% 35% 11%	600
	21st to end	Night	9% 2 6% 32% 42% 10%	600
July	1st to 10th	Night	11% 3 5% 24% 46% 11%	585
	11th to 20th	Night	10% 3 4 25% 45% 13%	582
	21st to end	Night	10% 4 4 25% 46% 11%	657
August	1st to 10th	Night	9% 3 5% 27% 45% 11%	597
	11th to 20th	Night	12% 3 8% 30% 39% 8%	594
	21st to end	Night	12% 3 8% 26% 42% 9%	660
September	1st to 10th	Night	10% 4 12% 27% 40% 9%	739
	11th to 20th	Night	13% 3 11% 32% 37% 4	800
	21st to end	Night	15% 4 14% 34% 30% 3	800
October	1st to 10th	Night	12% 6% 20% 33% 23% 6%	800
	11th to 20th	Night	15% 8% 25% 31% 20% 2	800
	21st to end	Night	16% 11% 21% 34% 15% 2	880
November	1st to 10th	Night	18% 8% 24% 32% 15% 3	820
	11th to 20th	Night	17% 16% 25% 29% 11% 2	840
	21st to end	Night	23% 16% 25% 26% 10% 1	840
December	1st to 10th	Night	28% 17% 23% 24% 8%	840
	11th to 20th	Night	26% 13% 25% 29% 7% 1	840
	21st to end	Night	28% 14% 25% 27% 6%	924

Page generated at 2026-02-28 01:40:26. Version ac07

Copyright © 2026 Attilla Danko.