Lexington Trails
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lexington Trails clear sky chart from 2005-11-06 to 2024-01-16.

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% 8% 3 6% 6% 3 5% 5% 5% 7% 38%	75307
	Night	15% 9% 3 6% 5% 3 4 4 5% 7% 39%	74467
Transparency	Day	46% 4 11% 22% 15% 2	75022
	Night	46% 4 11% 22% 15% 3	74272
Seeing	Day	19% 13% 27% 23% 13% 6%	14128
	Night	19% 11% 25% 27% 15% 2	23819

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	17% 12% 6% 9% 6% 2 4 4 4 5% 30%	1543
	11th to 20th	Day	21% 12% 6% 9% 6% 4 4 3 3 5% 26%	1671
	21st to end	Day	15% 15% 6% 8% 6% 3 5% 3 4 6% 29%	1782
February	1st to 10th	Day	19% 13% 5% 8% 5% 3 3 3 4 6% 30%	1742
	11th to 20th	Day	18% 12% 5% 7% 6% 3 4 4 4 6% 31%	1748
	21st to end	Day	20% 12% 5% 7% 5% 3 5% 4 4 6% 30%	1480
March	1st to 10th	Day	20% 9% 3 5% 5% 3 4 4 4 5% 37%	1805
	11th to 20th	Day	19% 11% 3 6% 7% 3 4 4 4 6% 32%	1980
	21st to end	Day	21% 10% 4 6% 6% 3 5% 4 4 6% 31%	2178
April	1st to 10th	Day	15% 8% 3 6% 5% 3 5% 5% 5% 8% 38%	2130
	11th to 20th	Day	18% 8% 3 5% 4 3 4 4 4 6% 40%	2164
	21st to end	Day	18% 7% 3 6% 6% 4 5% 4 5% 6% 37%	2340
May	1st to 10th	Day	21% 7% 2 7% 6% 3 5% 4 5% 7% 34%	2340
	11th to 20th	Day	20% 8% 3 6% 5% 3 5% 5% 5% 6% 35%	2301
	21st to end	Day	8% 7% 2 7% 7% 4 7% 6% 8% 9% 35%	2531
June	1st to 10th	Day	12% 5% 2 5% 6% 3 5% 6% 6% 8% 42%	2340
	11th to 20th	Day	10% 4 2 5% 6% 4 6% 5% 5% 8% 43%	2482
	21st to end	Day	9% 4 3 5% 6% 5% 6% 5% 6% 9% 41%	2520
July	1st to 10th	Day	13% 6% 3 6% 5% 4 5% 6% 6% 9% 37%	2520
	11th to 20th	Day	9% 4 2 5% 7% 4 6% 6% 7% 11% 39%	2407
	21st to end	Day	11% 5% 3 5% 5% 4 6% 5% 7% 8% 41%	2547
August	1st to 10th	Day	9% 4 2 6% 5% 3 6% 6% 7% 10% 41%	2327
	11th to 20th	Day	8% 7% 2 7% 6% 3 6% 6% 7% 10% 38%	2293
	21st to end	Day	8% 5% 2 5% 6% 4 5% 5% 6% 9% 45%	2376
September	1st to 10th	Day	15% 4 2 5% 5% 3 5% 5% 4 6% 45%	2052
	11th to 20th	Day	9% 4 2 6% 5% 3 5% 3 6% 8% 49%	1980
	21st to end	Day	15% 5% 2 4 5% 2 4 4 4 6% 49%	1980
October	1st to 10th	Day	12% 5% 2 5% 5% 3 5% 4 5% 6% 50%	1980
	11th to 20th	Day	14% 6% 2 5% 5% 2 4 4 5% 6% 46%	1844
	21st to end	Day	20% 7% 2 6% 5% 3 3 4 4 7% 40%	1845
November	1st to 10th	Day	11% 6% 3 4 3 3 3 4 3 5% 55%	1672
	11th to 20th	Day	15% 10% 4 6% 4 3 4 4 4 5% 41%	1710
	21st to end	Day	19% 9% 4 6% 4 2 3 4 4 5% 39%	1710
December	1st to 10th	Day	22% 13% 5% 7% 6% 2 4 4 4 5% 28%	1710
	11th to 20th	Day	16% 14% 5% 7% 6% 3 4 4 4 5% 32%	2153
	21st to end	Day	20% 19% 5% 7% 7% 4 4 4 3 5% 21%	3124
January	1st to 10th	Night	16% 12% 6% 11% 7% 3 4 5% 4 6% 28%	2580
	11th to 20th	Night	21% 14% 5% 9% 7% 3 3 3 4 4 26%	2417
	21st to end	Night	18% 13% 5% 8% 6% 3 4 4 4 5% 30%	2574
February	1st to 10th	Night	22% 13% 6% 8% 5% 3 4 4 4 5% 27%	2215
	11th to 20th	Night	19% 10% 4 8% 6% 3 4 4 4 5% 31%	2098
	21st to end	Night	23% 13% 4 7% 6% 3 3 4 4 5% 29%	1776
March	1st to 10th	Night	18% 9% 3 7% 6% 3 4 4 4 4 38%	2154
	11th to 20th	Night	20% 9% 4 6% 4 2 3 4 4 7% 36%	1980
	21st to end	Night	19% 9% 4 7% 5% 2 5% 4 5% 8% 33%	2178
April	1st to 10th	Night	13% 6% 4 5% 5% 3 6% 5% 6% 8% 38%	1846
	11th to 20th	Night	16% 8% 3 5% 5% 3 5% 3 5% 6% 42%	1743
	21st to end	Night	18% 7% 3 6% 6% 3 3 4 5% 7% 38%	1620
May	1st to 10th	Night	16% 8% 4 6% 5% 3 5% 5% 6% 7% 33%	1620
	11th to 20th	Night	15% 6% 2 5% 6% 4 5% 7% 6% 7% 37%	1592
	21st to end	Night	8% 6% 2 5% 4 3 5% 6% 9% 11% 41%	1744
June	1st to 10th	Night	9% 4 2 4 5% 3 5% 5% 5% 9% 50%	1620
	11th to 20th	Night	7% 4 2 6% 5% 3 4 4 6% 11% 48%	1472
	21st to end	Night	7% 4 1 5% 3 4 5% 7% 8% 9% 47%	1440
July	1st to 10th	Night	11% 5% 2 6% 7% 3 4 5% 6% 7% 44%	1440
	11th to 20th	Night	6% 4 1 5% 5% 3 5% 4 6% 10% 50%	1548
	21st to end	Night	9% 5% 2 4 6% 3 5% 5% 5% 8% 49%	1771
August	1st to 10th	Night	9% 4 2 5% 4 3 4 4 6% 10% 48%	1611
	11th to 20th	Night	6% 5% 3 5% 5% 4 5% 5% 7% 9% 46%	1605
	21st to end	Night	7% 3 2 4 3 3 4 5% 5% 11% 53%	1980
September	1st to 10th	Night	13% 4 2 4 4 3 2 4 5% 8% 50%	1889
	11th to 20th	Night	8% 4 2 4 4 2 4 4 5% 9% 53%	1980
	21st to end	Night	13% 5% 2 5% 3 3 4 4 4 6% 53%	1980
October	1st to 10th	Night	9% 5% 2 4 4 3 4 4 5% 6% 55%	1980
	11th to 20th	Night	15% 6% 2 4 4 4 4 4 5% 7% 45%	2114
	21st to end	Night	19% 8% 2 5% 4 4 4 4 4 6% 41%	2510
November	1st to 10th	Night	13% 6% 3 4 3 2 4 4 5% 6% 50%	2406
	11th to 20th	Night	15% 8% 3 5% 5% 3 4 4 4 7% 42%	2470
	21st to end	Night	20% 10% 3 6% 4 3 5% 5% 4 6% 37%	2470
December	1st to 10th	Night	21% 12% 4 6% 5% 3 4 4 3 6% 31%	2470
	11th to 20th	Night	18% 12% 5% 8% 4 3 4 3 4 6% 33%	3042
	21st to end	Night	20% 19% 6% 9% 7% 4 4 4 4 5% 19%	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	57% 3 9% 18% 12% 1	1544
	11th to 20th	Day	63% 2 9% 17% 8% 1	1671
	21st to end	Day	57% 2 9% 23% 7% 1	1782
February	1st to 10th	Day	58% 3 8% 21% 9% 2	1742
	11th to 20th	Day	56% 3 9% 21% 10% 2	1758
	21st to end	Day	55% 3 10% 20% 10% 2	1480
March	1st to 10th	Day	50% 3 9% 22% 15% 1	1805
	11th to 20th	Day	54% 3 9% 19% 12% 3	1980
	21st to end	Day	55% 3 9% 21% 9% 2	2178
April	1st to 10th	Day	45% 4 11% 25% 14% 2	2130
	11th to 20th	Day	46% 3 9% 22% 17% 4	2164
	21st to end	Day	48% 4 10% 24% 11% 2	2340
May	1st to 10th	Day	51% 4 12% 23% 10% 1	2340
	11th to 20th	Day	51% 4 12% 18% 13% 1	2305
	21st to end	Day	42% 6% 16% 21% 13% 1	2531
June	1st to 10th	Day	40% 5% 11% 25% 17% 2	2340
	11th to 20th	Day	38% 5% 14% 23% 18% 2	2482
	21st to end	Day	39% 6% 13% 22% 15% 4	2520
July	1st to 10th	Day	44% 6% 11% 20% 17% 3	2451
	11th to 20th	Day	37% 7% 14% 23% 17% 2	2334
	21st to end	Day	39% 6% 14% 25% 14% 3	2405
August	1st to 10th	Day	36% 7% 14% 26% 15% 1	2314
	11th to 20th	Day	40% 5% 12% 27% 15% 1	2293
	21st to end	Day	35% 5% 14% 23% 18% 6%	2376
September	1st to 10th	Day	39% 5% 10% 22% 18% 6%	2052
	11th to 20th	Day	34% 5% 12% 25% 23% 3	1980
	21st to end	Day	37% 3 9% 25% 24% 2	1980
October	1st to 10th	Day	35% 4 11% 25% 23% 3	1980
	11th to 20th	Day	39% 3 8% 27% 20% 3	1844
	21st to end	Day	47% 2 11% 23% 16% 3	1845
November	1st to 10th	Day	33% 3 9% 29% 22% 4	1672
	11th to 20th	Day	46% 3 7% 23% 18% 3	1710
	21st to end	Day	48% 2 8% 23% 17% 1	1710
December	1st to 10th	Day	59% 2 10% 19% 8% 1	1710
	11th to 20th	Day	55% 3 8% 20% 14% 1	2150
	21st to end	Day	67% 3 9% 13% 8% 1	3124
January	1st to 10th	Night	60% 3 7% 19% 10% 1	2580
	11th to 20th	Night	63% 2 9% 17% 7% 1	2417
	21st to end	Night	57% 3 9% 21% 8% 2	2574
February	1st to 10th	Night	61% 3 10% 20% 6% 1	2215
	11th to 20th	Night	56% 3 8% 21% 11% 1	2099
	21st to end	Night	59% 3 11% 15% 10% 3	1776
March	1st to 10th	Night	49% 3 7% 21% 17% 3	2154
	11th to 20th	Night	49% 3 11% 22% 13% 2	1980
	21st to end	Night	51% 4 11% 24% 9% 2	2178
April	1st to 10th	Night	43% 5% 10% 24% 15% 2	1846
	11th to 20th	Night	44% 3 9% 18% 20% 6%	1743
	21st to end	Night	46% 4 11% 22% 13% 3	1620
May	1st to 10th	Night	49% 5% 12% 22% 10% 3	1620
	11th to 20th	Night	46% 6% 14% 20% 13% 2	1593
	21st to end	Night	33% 8% 18% 21% 17% 3	1745
June	1st to 10th	Night	31% 4 14% 28% 18% 4	1620
	11th to 20th	Night	31% 5% 16% 23% 20% 4	1472
	21st to end	Night	30% 8% 17% 24% 17% 5%	1440
July	1st to 10th	Night	38% 6% 13% 21% 17% 5%	1400
	11th to 20th	Night	30% 5% 14% 28% 19% 4	1498
	21st to end	Night	32% 5% 14% 30% 16% 2	1672
August	1st to 10th	Night	33% 5% 16% 28% 16% 3	1600
	11th to 20th	Night	32% 7% 13% 30% 17% 1	1605
	21st to end	Night	27% 4 16% 28% 20% 5%	1980
September	1st to 10th	Night	33% 4 14% 24% 19% 6%	1889
	11th to 20th	Night	29% 5% 11% 26% 25% 3	1980
	21st to end	Night	34% 4 8% 24% 26% 4	1980
October	1st to 10th	Night	30% 3 10% 28% 24% 4	1980
	11th to 20th	Night	39% 4 8% 24% 22% 3	2114
	21st to end	Night	45% 3 8% 23% 18% 3	2510
November	1st to 10th	Night	36% 3 9% 24% 25% 4	2406
	11th to 20th	Night	45% 3 8% 20% 21% 4	2470
	21st to end	Night	50% 3 10% 22% 14% 1	2470
December	1st to 10th	Night	57% 3 10% 20% 11% 1	2470
	11th to 20th	Night	54% 2 10% 21% 12% 1	3044
	21st to end	Night	68% 3 9% 13% 7%	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	23% 23% 36% 13% 4 1	270
	11th to 20th	Day	29% 25% 33% 12% 1	257
	21st to end	Day	27% 30% 31% 10% 2	264
February	1st to 10th	Day	32% 29% 30% 8% 2	240
	11th to 20th	Day	34% 29% 30% 7%	240
	21st to end	Day	36% 17% 40% 6% 2	198
March	1st to 10th	Day	25% 31% 35% 8% 2	245
	11th to 20th	Day	28% 22% 31% 13% 6%	420
	21st to end	Day	31% 21% 27% 15% 6%	462
April	1st to 10th	Day	21% 21% 30% 18% 9% 1	420
	11th to 20th	Day	26% 17% 26% 20% 8% 3	412
	21st to end	Day	26% 16% 35% 13% 8% 1	420
May	1st to 10th	Day	26% 12% 34% 15% 7% 4	423
	11th to 20th	Day	21% 10% 30% 25% 10% 5%	447
	21st to end	Day	14% 8% 27% 26% 17% 8%	485
June	1st to 10th	Day	14% 8% 22% 32% 17% 7%	450
	11th to 20th	Day	10% 8% 27% 33% 16% 7%	592
	21st to end	Day	11% 7% 29% 28% 17% 7%	630
July	1st to 10th	Day	15% 4 18% 26% 21% 15%	621
	11th to 20th	Day	10% 5% 20% 31% 22% 12%	507
	21st to end	Day	13% 3 19% 32% 20% 13%	488
August	1st to 10th	Day	12% 4 17% 32% 22% 14%	446
	11th to 20th	Day	12% 3 19% 36% 20% 10%	439
	21st to end	Day	10% 3 17% 34% 24% 12%	495
September	1st to 10th	Day	14% 4 16% 31% 25% 9%	450
	11th to 20th	Day	10% 4 17% 30% 24% 14%	450
	21st to end	Day	19% 7% 22% 23% 22% 7%	450
October	1st to 10th	Day	12% 9% 26% 30% 17% 6%	450
	11th to 20th	Day	19% 15% 32% 21% 11% 2	450
	21st to end	Day	23% 14% 38% 21% 4 1	360
November	1st to 10th	Day	16% 16% 34% 25% 5% 4	270
	11th to 20th	Day	22% 23% 27% 21% 5% 1	270
	21st to end	Day	27% 15% 35% 19% 4	270
December	1st to 10th	Day	27% 22% 34% 12% 5%	270
	11th to 20th	Day	23% 21% 36% 15% 6%	270
	21st to end	Day	29% 20% 35% 11% 4	297
January	1st to 10th	Night	23% 23% 31% 19% 5%	882
	11th to 20th	Night	31% 20% 31% 16% 3	744
	21st to end	Night	25% 20% 32% 21% 2	792
February	1st to 10th	Night	30% 15% 31% 22% 2	720
	11th to 20th	Night	27% 21% 32% 20% 1	703
	21st to end	Night	32% 16% 35% 16% 1	592
March	1st to 10th	Night	25% 18% 30% 23% 4	720
	11th to 20th	Night	26% 16% 30% 20% 7% 1	720
	21st to end	Night	25% 13% 30% 24% 7%	792
April	1st to 10th	Night	17% 15% 33% 29% 6%	586
	11th to 20th	Night	18% 14% 31% 25% 10% 2	533
	21st to end	Night	20% 10% 34% 27% 8% 1	540
May	1st to 10th	Night	20% 10% 32% 23% 13% 1	540
	11th to 20th	Night	19% 7% 22% 33% 17% 2	531
	21st to end	Night	10% 3 22% 34% 27% 5%	584
June	1st to 10th	Night	11% 3 20% 39% 25% 3	540
	11th to 20th	Night	9% 4 19% 41% 25% 4	540
	21st to end	Night	7% 4 25% 36% 25% 3	540
July	1st to 10th	Night	14% 1 14% 30% 30% 11%	525
	11th to 20th	Night	7% 2 14% 37% 35% 5%	522
	21st to end	Night	11% 1 11% 40% 33% 4	591
August	1st to 10th	Night	10% 2 8% 37% 38% 5%	537
	11th to 20th	Night	7% 3 11% 38% 35% 6%	534
	21st to end	Night	8% 1 13% 32% 39% 7%	594
September	1st to 10th	Night	14% 3 12% 35% 30% 5%	629
	11th to 20th	Night	10% 4 16% 30% 35% 6%	720
	21st to end	Night	14% 7% 19% 31% 27% 2	720
October	1st to 10th	Night	11% 7% 22% 33% 23% 4	720
	11th to 20th	Night	19% 10% 25% 31% 14% 1	720
	21st to end	Night	22% 12% 29% 25% 10% 1	792
November	1st to 10th	Night	16% 11% 27% 27% 16% 2	740
	11th to 20th	Night	21% 16% 29% 24% 9% 1	760
	21st to end	Night	26% 14% 24% 27% 8% 1	760
December	1st to 10th	Night	30% 15% 29% 21% 5%	760
	11th to 20th	Night	26% 15% 29% 23% 6% 1	760
	21st to end	Night	31% 16% 29% 20% 4	836

Page generated at 2024-01-13 19:28:29. Version ac07

Copyright 2024 Attilla Danko