Finger Lakes Regional Airport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Finger Lakes Regional Airport clear sky chart from 2005-11-06 to 2024-01-31.

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	16% 10% 4 8% 6% 4 5% 5% 5% 7% 30%	74868
	Night	18% 11% 4 8% 6% 3 5% 5% 5% 6% 29%	75257
Transparency	Day	53% 8% 12% 18% 9% 1	74575
	Night	55% 7% 11% 17% 8% 1	75084
Seeing	Day	23% 15% 29% 20% 10% 3	13555
	Night	23% 14% 27% 25% 9% 1	22959

By Month

Percentage Cloud Cover NE (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	14% 16% 7% 14% 9% 4 7% 6% 4 4 15%	1517
	11th to 20th	Day	18% 17% 7% 14% 10% 3 5% 4 5% 4 12%	1538
	21st to end	Day	14% 15% 7% 13% 12% 6% 7% 5% 4 5% 13%	1872
February	1st to 10th	Day	18% 14% 8% 14% 10% 4 5% 5% 4 4 14%	1620
	11th to 20th	Day	15% 15% 9% 14% 8% 5% 6% 5% 5% 5% 14%	1574
	21st to end	Day	21% 12% 5% 12% 9% 3 6% 6% 4 4 18%	1480
March	1st to 10th	Day	14% 13% 8% 11% 8% 5% 6% 5% 4 5% 20%	1869
	11th to 20th	Day	16% 14% 6% 9% 7% 3 5% 4 4 6% 26%	1980
	21st to end	Day	21% 10% 4 8% 6% 4 5% 4 4 6% 28%	2247
April	1st to 10th	Day	18% 12% 5% 7% 6% 3 5% 4 4 6% 30%	2160
	11th to 20th	Day	20% 8% 3 5% 5% 3 4 4 4 6% 36%	2134
	21st to end	Day	21% 11% 3 6% 5% 3 4 4 5% 7% 32%	2220
May	1st to 10th	Day	17% 9% 3 7% 7% 4 5% 4 5% 6% 34%	2448
	11th to 20th	Day	15% 7% 3 6% 6% 4 5% 5% 6% 7% 38%	2478
	21st to end	Day	14% 6% 2 5% 5% 3 5% 5% 6% 8% 41%	2725
June	1st to 10th	Day	16% 8% 3 5% 5% 3 5% 5% 6% 8% 36%	2520
	11th to 20th	Day	15% 6% 3 5% 5% 3 5% 5% 7% 10% 38%	2520
	21st to end	Day	13% 6% 3 5% 5% 4 6% 5% 6% 9% 38%	2520
July	1st to 10th	Day	10% 5% 3 4 6% 4 4 6% 6% 10% 42%	2520
	11th to 20th	Day	11% 5% 3 5% 6% 3 6% 6% 7% 9% 39%	2520
	21st to end	Day	12% 5% 3 6% 5% 5% 8% 6% 7% 9% 36%	2720
August	1st to 10th	Day	11% 4 2 5% 6% 5% 5% 7% 8% 9% 38%	2327
	11th to 20th	Day	12% 6% 3 7% 7% 5% 6% 6% 7% 8% 33%	2272
	21st to end	Day	14% 6% 2 5% 5% 5% 6% 6% 6% 8% 36%	2376
September	1st to 10th	Day	15% 6% 3 6% 4 3 4 5% 6% 8% 40%	2160
	11th to 20th	Day	14% 6% 3 5% 5% 3 5% 5% 5% 8% 42%	2160
	21st to end	Day	16% 6% 3 7% 6% 4 6% 5% 5% 7% 36%	1903
October	1st to 10th	Day	16% 9% 3 6% 6% 3 6% 4 5% 7% 34%	1800
	11th to 20th	Day	20% 8% 4 6% 6% 4 5% 6% 6% 7% 29%	1800
	21st to end	Day	25% 13% 4 7% 7% 3 4 4 4 6% 23%	1936
November	1st to 10th	Day	15% 11% 4 7% 7% 4 5% 4 5% 7% 31%	1671
	11th to 20th	Day	16% 13% 6% 9% 7% 3 5% 5% 6% 6% 25%	1563
	21st to end	Day	20% 14% 5% 8% 8% 3 5% 5% 4 7% 21%	1520
December	1st to 10th	Day	21% 17% 6% 11% 8% 3 5% 4 3 6% 16%	1520
	11th to 20th	Day	20% 16% 7% 11% 7% 3 4 4 4 5% 18%	1906
	21st to end	Day	28% 17% 5% 9% 7% 4 4 4 3 4 13%	2772
January	1st to 10th	Night	17% 19% 7% 12% 9% 5% 6% 4 4 4 14%	2649
	11th to 20th	Night	19% 17% 7% 12% 8% 4 5% 5% 4 6% 14%	2641
	21st to end	Night	14% 17% 8% 11% 11% 5% 6% 5% 4 5% 14%	2711
February	1st to 10th	Night	19% 14% 7% 12% 7% 4 5% 4 4 5% 18%	2340
	11th to 20th	Night	16% 15% 6% 12% 8% 4 6% 5% 4 5% 19%	2270
	21st to end	Night	19% 12% 6% 13% 7% 4 5% 5% 5% 5% 21%	1776
March	1st to 10th	Night	16% 14% 6% 9% 9% 3 5% 5% 4 5% 23%	2074
	11th to 20th	Night	18% 14% 5% 9% 6% 3 4 4 4 5% 28%	1979
	21st to end	Night	19% 11% 5% 8% 5% 4 4 4 5% 5% 30%	2107
April	1st to 10th	Night	20% 10% 5% 7% 6% 3 5% 4 5% 6% 29%	1800
	11th to 20th	Night	20% 9% 2 6% 6% 3 5% 4 4 6% 34%	1775
	21st to end	Night	19% 9% 3 7% 6% 2 4 4 5% 7% 34%	1756
May	1st to 10th	Night	19% 9% 4 6% 6% 3 5% 5% 4 6% 32%	1510
	11th to 20th	Night	13% 6% 3 6% 6% 4 5% 4 7% 10% 38%	1415
	21st to end	Night	11% 5% 2 5% 5% 4 4 5% 5% 8% 44%	1550
June	1st to 10th	Night	17% 5% 3 6% 5% 4 5% 5% 7% 8% 36%	1440
	11th to 20th	Night	12% 6% 3 6% 5% 4 5% 5% 6% 8% 41%	1440
	21st to end	Night	12% 6% 2 4 6% 3 5% 6% 5% 8% 43%	1440
July	1st to 10th	Night	8% 4 3 5% 5% 3 7% 5% 7% 9% 45%	1440
	11th to 20th	Night	10% 4 2 5% 5% 3 5% 5% 5% 8% 47%	1440
	21st to end	Night	13% 5% 1 5% 5% 3 5% 5% 7% 9% 42%	1595
August	1st to 10th	Night	10% 5% 2 5% 6% 3 5% 5% 7% 9% 45%	1611
	11th to 20th	Night	13% 4 2 6% 6% 4 5% 6% 6% 6% 41%	1611
	21st to end	Night	12% 5% 2 5% 4 3 5% 5% 6% 9% 45%	1980
September	1st to 10th	Night	15% 6% 2 6% 5% 3 5% 4 5% 9% 41%	1800
	11th to 20th	Night	15% 5% 2 5% 5% 3 3 4 5% 8% 45%	1800
	21st to end	Night	16% 7% 3 5% 5% 3 6% 6% 6% 7% 38%	2054
October	1st to 10th	Night	20% 8% 3 7% 7% 3 4 5% 5% 6% 33%	2160
	11th to 20th	Night	21% 8% 3 6% 5% 3 4 4 6% 7% 31%	2160
	21st to end	Night	28% 11% 4 8% 6% 3 4 4 4 5% 24%	2420
November	1st to 10th	Night	17% 12% 4 6% 6% 3 5% 4 4 5% 33%	2407
	11th to 20th	Night	17% 12% 4 7% 6% 4 4 5% 5% 8% 28%	2614
	21st to end	Night	18% 17% 5% 7% 5% 4 5% 5% 5% 7% 23%	2660
December	1st to 10th	Night	21% 17% 7% 9% 7% 3 5% 5% 5% 5% 17%	2660
	11th to 20th	Night	21% 16% 6% 10% 7% 4 5% 4 4 4 20%	3288
	21st to end	Night	31% 16% 5% 8% 6% 3 5% 5% 4 5% 13%	4884

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	72% 7% 9% 9% 3	1518
	11th to 20th	Day	75% 7% 9% 6% 3	1538
	21st to end	Day	74% 6% 10% 7% 3	1872
February	1st to 10th	Day	74% 6% 9% 8% 3	1620
	11th to 20th	Day	73% 6% 7% 11% 2	1583
	21st to end	Day	69% 7% 8% 10% 5% 1	1480
March	1st to 10th	Day	65% 8% 11% 13% 4	1872
	11th to 20th	Day	60% 6% 9% 14% 10% 1	1980
	21st to end	Day	57% 6% 9% 16% 11% 2	2247
April	1st to 10th	Day	56% 6% 10% 17% 10% 1	2160
	11th to 20th	Day	49% 6% 11% 19% 13% 2	2134
	21st to end	Day	53% 6% 8% 18% 13% 2	2220
May	1st to 10th	Day	52% 6% 10% 19% 11% 2	2448
	11th to 20th	Day	45% 7% 11% 22% 13% 2	2482
	21st to end	Day	40% 8% 15% 23% 12% 1	2725
June	1st to 10th	Day	45% 9% 11% 20% 15% 1	2520
	11th to 20th	Day	41% 8% 14% 24% 13% 1	2520
	21st to end	Day	41% 10% 13% 22% 13% 1	2520
July	1st to 10th	Day	37% 9% 12% 27% 13% 2	2450
	11th to 20th	Day	37% 10% 17% 24% 11% 1	2445
	21st to end	Day	41% 11% 13% 22% 12% 1	2568
August	1st to 10th	Day	39% 11% 15% 23% 12% 1	2314
	11th to 20th	Day	44% 11% 14% 22% 8%	2272
	21st to end	Day	43% 9% 13% 23% 11% 1	2376
September	1st to 10th	Day	41% 8% 12% 26% 12% 1	2160
	11th to 20th	Day	40% 7% 12% 23% 16% 1	2160
	21st to end	Day	47% 8% 11% 23% 11% 1	1903
October	1st to 10th	Day	49% 8% 13% 18% 11% 1	1800
	11th to 20th	Day	53% 8% 14% 18% 7%	1800
	21st to end	Day	62% 7% 11% 13% 6% 1	1936
November	1st to 10th	Day	52% 8% 12% 16% 10% 1	1671
	11th to 20th	Day	58% 7% 13% 14% 7% 1	1563
	21st to end	Day	62% 9% 14% 13% 2	1520
December	1st to 10th	Day	71% 6% 11% 10% 2	1520
	11th to 20th	Day	70% 7% 12% 7% 4	1906
	21st to end	Day	76% 7% 8% 8% 1	2772
January	1st to 10th	Night	74% 7% 7% 8% 4	2649
	11th to 20th	Night	72% 7% 10% 8% 3	2641
	21st to end	Night	73% 6% 8% 9% 3 1	2711
February	1st to 10th	Night	68% 6% 9% 10% 6%	2340
	11th to 20th	Night	67% 7% 9% 12% 4 1	2272
	21st to end	Night	64% 6% 10% 12% 7%	1776
March	1st to 10th	Night	63% 6% 10% 15% 5%	2084
	11th to 20th	Night	58% 7% 8% 18% 9% 1	1980
	21st to end	Night	56% 5% 8% 17% 12% 2	2107
April	1st to 10th	Night	56% 7% 10% 18% 8% 2	1800
	11th to 20th	Night	52% 6% 10% 16% 14% 1	1775
	21st to end	Night	49% 7% 10% 18% 13% 3	1756
May	1st to 10th	Night	52% 7% 9% 16% 13% 3	1510
	11th to 20th	Night	41% 8% 11% 23% 15% 2	1416
	21st to end	Night	37% 9% 15% 22% 14% 2	1551
June	1st to 10th	Night	43% 8% 12% 22% 14% 1	1440
	11th to 20th	Night	40% 8% 14% 21% 15% 2	1440
	21st to end	Night	38% 9% 11% 26% 15% 1	1440
July	1st to 10th	Night	34% 10% 14% 22% 17% 4	1400
	11th to 20th	Night	33% 8% 14% 29% 15% 1	1392
	21st to end	Night	36% 9% 13% 25% 14% 2	1506
August	1st to 10th	Night	35% 10% 14% 28% 12% 1	1600
	11th to 20th	Night	41% 9% 13% 28% 8%	1611
	21st to end	Night	35% 9% 15% 27% 13% 2	1980
September	1st to 10th	Night	40% 8% 14% 24% 13% 2	1800
	11th to 20th	Night	38% 6% 12% 26% 16% 1	1800
	21st to end	Night	43% 8% 13% 23% 12% 1	2054
October	1st to 10th	Night	51% 8% 12% 17% 12%	2160
	11th to 20th	Night	51% 7% 14% 18% 9% 1	2160
	21st to end	Night	63% 6% 11% 12% 6% 1	2420
November	1st to 10th	Night	53% 7% 11% 18% 9% 2	2407
	11th to 20th	Night	55% 8% 13% 15% 7% 2	2614
	21st to end	Night	62% 7% 13% 14% 4	2660
December	1st to 10th	Night	69% 7% 11% 10% 2	2660
	11th to 20th	Night	68% 7% 10% 12% 3	3288
	21st to end	Night	73% 7% 10% 9% 1	4884

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	30% 19% 35% 11% 6%	180
	11th to 20th	Day	30% 25% 29% 14% 2 1	189
	21st to end	Day	26% 22% 36% 14% 2 1	294
February	1st to 10th	Day	32% 26% 35% 7%	240
	11th to 20th	Day	32% 25% 38% 5%	241
	21st to end	Day	34% 20% 32% 12% 2	346
March	1st to 10th	Day	24% 23% 31% 20% 3	420
	11th to 20th	Day	28% 23% 28% 16% 5%	420
	21st to end	Day	31% 20% 28% 14% 5% 2	462
April	1st to 10th	Day	29% 17% 29% 16% 8%	420
	11th to 20th	Day	27% 20% 25% 15% 10% 4	412
	21st to end	Day	31% 17% 27% 16% 8% 1	420
May	1st to 10th	Day	24% 15% 31% 19% 8% 3	423
	11th to 20th	Day	21% 12% 30% 25% 10% 2	447
	21st to end	Day	18% 11% 29% 24% 14% 4	485
June	1st to 10th	Day	21% 12% 27% 25% 12% 2	450
	11th to 20th	Day	17% 11% 29% 27% 14% 2	450
	21st to end	Day	15% 11% 35% 26% 9% 3	450
July	1st to 10th	Day	11% 8% 24% 34% 18% 5%	445
	11th to 20th	Day	12% 8% 25% 29% 22% 4	444
	21st to end	Day	12% 6% 35% 30% 13% 3	488
August	1st to 10th	Day	13% 6% 25% 30% 20% 7%	446
	11th to 20th	Day	17% 4 30% 24% 17% 9%	439
	21st to end	Day	15% 8% 27% 24% 17% 9%	495
September	1st to 10th	Day	18% 11% 20% 26% 15% 10%	450
	11th to 20th	Day	13% 10% 25% 23% 19% 10%	450
	21st to end	Day	18% 14% 25% 22% 16% 6%	450
October	1st to 10th	Day	24% 12% 26% 19% 15% 5%	450
	11th to 20th	Day	25% 17% 31% 17% 8% 1	450
	21st to end	Day	34% 15% 31% 16% 4	473
November	1st to 10th	Day	25% 18% 28% 21% 8% 1	365
	11th to 20th	Day	29% 24% 30% 14% 2	223
	21st to end	Day	33% 25% 29% 12% 1	180
December	1st to 10th	Day	30% 22% 34% 8% 4 1	180
	11th to 20th	Day	29% 25% 32% 12% 2	180
	21st to end	Day	32% 21% 38% 9% 1	198
January	1st to 10th	Night	29% 22% 30% 16% 3	760
	11th to 20th	Night	29% 22% 29% 17% 3 1	760
	21st to end	Night	22% 21% 35% 19% 3	835
February	1st to 10th	Night	28% 21% 33% 17% 2	720
	11th to 20th	Night	25% 22% 35% 15% 2	703
	21st to end	Night	28% 19% 33% 17% 3	592
March	1st to 10th	Night	27% 18% 29% 22% 4	720
	11th to 20th	Night	25% 21% 27% 23% 4	720
	21st to end	Night	27% 15% 28% 22% 8% 1	792
April	1st to 10th	Night	27% 14% 31% 24% 4	720
	11th to 20th	Night	25% 15% 28% 24% 8% 1	711
	21st to end	Night	24% 12% 28% 27% 8%	676
May	1st to 10th	Night	27% 9% 21% 33% 10% 1	430
	11th to 20th	Night	17% 7% 29% 36% 10% 1	354
	21st to end	Night	13% 7% 28% 36% 17% 1	389
June	1st to 10th	Night	18% 6% 22% 37% 16% 1	360
	11th to 20th	Night	15% 8% 23% 38% 16%	360
	21st to end	Night	15% 4 27% 43% 10% 1	360
July	1st to 10th	Night	8% 4 19% 46% 20% 2	350
	11th to 20th	Night	11% 3 17% 45% 23% 1	348
	21st to end	Night	11% 5% 23% 44% 15% 1	415
August	1st to 10th	Night	12% 3 23% 37% 23% 2	537
	11th to 20th	Night	14% 4 15% 39% 25% 3	547
	21st to end	Night	12% 6% 21% 37% 22% 2	792
September	1st to 10th	Night	17% 6% 22% 33% 18% 3	720
	11th to 20th	Night	17% 6% 20% 30% 22% 6%	720
	21st to end	Night	18% 10% 23% 27% 19% 3	720
October	1st to 10th	Night	24% 9% 27% 20% 18% 2	720
	11th to 20th	Night	25% 14% 30% 24% 7% 1	720
	21st to end	Night	34% 15% 28% 20% 3	792
November	1st to 10th	Night	27% 13% 30% 23% 7%	740
	11th to 20th	Night	25% 20% 32% 17% 5% 2	760
	21st to end	Night	28% 20% 28% 19% 6%	760
December	1st to 10th	Night	32% 21% 27% 16% 3	760
	11th to 20th	Night	28% 22% 29% 18% 4	760
	21st to end	Night	34% 21% 29% 15% 2	836

Page generated at 2024-01-28 05:26:35. Version ac07

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