National Golf Links of America
Clear Sky Chart
History

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

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% 7% 2 6% 4 4 4 3 5% 7% 41%	127237
	Night	17% 8% 3 6% 4 4 4 3 5% 7% 40%	124789
Transparency	Day	28% 37% 8% 15% 11% 2	130781
	Night	29% 36% 7% 15% 11% 2	129332
Seeing	Day	20% 11% 29% 24% 12% 3	16623
	Night	21% 11% 27% 27% 12% 2	25758

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	13% 7% 2 5% 4 3 4 3 5% 7% 47%	3677
	11th to 20th	Day	15% 8% 2 5% 3 4 4 3 4 6% 46%	3650
	21st to end	Day	18% 9% 3 7% 5% 4 4 3 4 5% 40%	4160
February	1st to 10th	Day	18% 7% 2 6% 4 5% 5% 3 6% 7% 37%	1919
	11th to 20th	Day	16% 6% 2 6% 5% 4 3 3 5% 6% 43%	1948
	21st to end	Day	19% 8% 2 7% 4 3 3 4 5% 6% 38%	1650
March	1st to 10th	Day	20% 7% 2 4 3 3 3 2 4 6% 44%	4476
	11th to 20th	Day	12% 9% 2 5% 4 4 4 3 6% 7% 45%	4653
	21st to end	Day	18% 10% 3 5% 3 4 4 3 5% 6% 40%	5957
April	1st to 10th	Day	18% 8% 2 5% 4 4 3 3 5% 5% 41%	2400
	11th to 20th	Day	18% 6% 2 5% 4 3 4 3 5% 7% 44%	2374
	21st to end	Day	19% 6% 2 5% 3 4 4 4 6% 7% 42%	2520
May	1st to 10th	Day	27% 9% 3 5% 3 4 3 3 5% 8% 30%	5886
	11th to 20th	Day	20% 10% 3 7% 4 3 3 2 4 6% 38%	5988
	21st to end	Day	19% 8% 3 6% 3 3 4 3 6% 9% 36%	6949
June	1st to 10th	Day	16% 6% 1 5% 4 4 4 4 6% 9% 40%	2800
	11th to 20th	Day	13% 7% 2 6% 4 3 5% 4 6% 9% 41%	2800
	21st to end	Day	11% 6% 2 5% 4 5% 4 4 7% 9% 44%	2800
July	1st to 10th	Day	13% 9% 3 7% 4 4 5% 4 6% 9% 36%	6360
	11th to 20th	Day	11% 8% 3 7% 5% 4 5% 5% 7% 10% 34%	6360
	21st to end	Day	14% 7% 2 6% 4 3 4 3 5% 7% 44%	6926
August	1st to 10th	Day	16% 7% 2 6% 4 4 4 4 6% 9% 37%	4310
	11th to 20th	Day	10% 6% 2 6% 4 4 5% 3 6% 8% 46%	3889
	21st to end	Day	7% 3 2 4 4 4 4 5% 6% 10% 52%	4312
September	1st to 10th	Day	14% 6% 2 6% 4 3 3 3 5% 7% 47%	2400
	11th to 20th	Day	11% 5% 2 4 3 3 3 3 5% 6% 53%	2238
	21st to end	Day	19% 6% 2 6% 4 4 4 4 5% 7% 39%	2200
October	1st to 10th	Day	20% 5% 2 5% 3 3 3 2 5% 6% 46%	2200
	11th to 20th	Day	15% 5% 2 4 3 3 4 4 5% 8% 46%	1980
	21st to end	Day	18% 6% 3 5% 5% 4 4 3 5% 7% 41%	1980
November	1st to 10th	Day	14% 7% 1 5% 4 3 3 3 5% 5% 50%	1851
	11th to 20th	Day	15% 6% 2 5% 3 3 3 3 4 7% 47%	1890
	21st to end	Day	16% 9% 2 4 4 4 4 4 5% 6% 43%	1890
December	1st to 10th	Day	14% 7% 3 7% 4 4 4 3 4 8% 43%	2730
	11th to 20th	Day	21% 8% 2 4 3 2 2 2 3 5% 46%	3066
	21st to end	Day	19% 10% 3 8% 4 4 3 3 4 5% 38%	4048
January	1st to 10th	Night	14% 6% 2 5% 3 3 4 3 5% 6% 49%	6489
	11th to 20th	Night	15% 8% 3 7% 4 4 4 3 4 4 44%	6455
	21st to end	Night	17% 9% 3 7% 5% 4 5% 3 5% 6% 36%	7035
February	1st to 10th	Night	17% 9% 3 7% 5% 3 4 3 5% 7% 37%	2480
	11th to 20th	Night	19% 7% 2 5% 4 4 4 3 5% 8% 37%	2338
	21st to end	Night	20% 7% 2 6% 4 4 4 3 4 5% 40%	1980
March	1st to 10th	Night	21% 10% 2 5% 3 3 3 2 4 6% 41%	5364
	11th to 20th	Night	15% 12% 3 6% 4 3 4 3 5% 5% 41%	5304
	21st to end	Night	20% 9% 2 6% 4 3 4 3 5% 6% 37%	4972
April	1st to 10th	Night	19% 9% 2 5% 5% 4 4 3 5% 6% 38%	2000
	11th to 20th	Night	19% 7% 3 6% 4 3 4 3 5% 6% 42%	1975
	21st to end	Night	19% 8% 2 6% 4 3 3 3 4 6% 40%	1878
May	1st to 10th	Night	24% 13% 4 7% 4 4 4 3 4 6% 27%	4054
	11th to 20th	Night	25% 10% 3 6% 3 3 4 3 5% 6% 31%	3948
	21st to end	Night	21% 10% 3 6% 4 4 5% 4 6% 7% 30%	3926
June	1st to 10th	Night	17% 8% 3 6% 4 4 4 4 5% 8% 38%	1600
	11th to 20th	Night	17% 6% 2 5% 4 4 3 3 6% 9% 40%	1600
	21st to end	Night	12% 8% 2 7% 5% 5% 5% 5% 6% 9% 37%	1600
July	1st to 10th	Night	14% 12% 4 8% 4 4 5% 4 5% 8% 32%	3600
	11th to 20th	Night	15% 11% 3 7% 6% 4 4 4 7% 9% 30%	3600
	21st to end	Night	14% 7% 2 6% 5% 5% 4 3 5% 8% 41%	3926
August	1st to 10th	Night	22% 7% 3 6% 4 5% 5% 5% 6% 8% 31%	2807
	11th to 20th	Night	10% 7% 2 7% 5% 5% 6% 4 6% 9% 40%	3156
	21st to end	Night	7% 3 2 5% 4 3 4 4 6% 9% 54%	3586
September	1st to 10th	Night	15% 6% 2 6% 4 5% 6% 4 5% 6% 42%	2000
	11th to 20th	Night	14% 6% 2 4 3 2 3 3 5% 6% 51%	2161
	21st to end	Night	18% 8% 2 7% 4 4 4 3 5% 6% 39%	2200
October	1st to 10th	Night	19% 8% 2 6% 4 3 4 3 3 6% 42%	2200
	11th to 20th	Night	17% 7% 2 5% 3 3 3 3 4 6% 47%	2418
	21st to end	Night	19% 8% 3 7% 4 3 3 2 4 6% 40%	2860
November	1st to 10th	Night	13% 6% 3 6% 3 4 5% 3 4 6% 46%	2667
	11th to 20th	Night	18% 7% 2 5% 4 4 3 3 5% 5% 45%	2730
	21st to end	Night	15% 5% 2 5% 5% 4 4 4 6% 8% 43%	2730
December	1st to 10th	Night	15% 7% 3 6% 4 4 4 3 4 6% 43%	4652
	11th to 20th	Night	23% 9% 2 5% 3 3 3 2 4 5% 41%	5348
	21st to end	Night	18% 9% 3 6% 4 4 3 3 4 6% 41%	7150

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	29% 26% 3 23% 17% 1	3678
	11th to 20th	Day	28% 26% 7% 18% 15% 6%	3680
	21st to end	Day	38% 26% 7% 17% 12% 1	4160
February	1st to 10th	Day	18% 62% 7% 8% 4	1919
	11th to 20th	Day	18% 60% 2 10% 9% 1	1957
	21st to end	Day	17% 61% 5% 8% 6% 2	1650
March	1st to 10th	Day	33% 28% 7% 11% 12% 8%	4479
	11th to 20th	Day	27% 28% 11% 23% 10%	4653
	21st to end	Day	36% 27% 6% 10% 16% 4	5957
April	1st to 10th	Day	20% 61% 3 7% 7% 1	2400
	11th to 20th	Day	16% 62% 4 9% 10%	2374
	21st to end	Day	16% 62% 3 11% 7% 1	2520
May	1st to 10th	Day	43% 29% 14% 9% 4 1	5897
	11th to 20th	Day	39% 27% 9% 15% 9% 1	5992
	21st to end	Day	37% 27% 6% 20% 9%	6949
June	1st to 10th	Day	17% 61% 4 10% 8%	2800
	11th to 20th	Day	16% 62% 5% 10% 7% 1	2800
	21st to end	Day	14% 60% 6% 11% 9% 1	2800
July	1st to 10th	Day	37% 28% 10% 13% 11% 1	6290
	11th to 20th	Day	37% 26% 14% 16% 6%	6285
	21st to end	Day	31% 25% 9% 20% 14% 1	6728
August	1st to 10th	Day	34% 36% 10% 16% 5%	4296
	11th to 20th	Day	24% 36% 11% 24% 5%	3926
	21st to end	Day	16% 35% 11% 24% 13% 1	4312
September	1st to 10th	Day	17% 57% 6% 12% 8%	2400
	11th to 20th	Day	16% 57% 4 11% 12% 1	2238
	21st to end	Day	23% 57% 5% 9% 7%	2200
October	1st to 10th	Day	21% 35% 7% 15% 18% 4	3590
	11th to 20th	Day	14% 35% 7% 16% 26% 2	3196
	21st to end	Day	18% 35% 10% 20% 15% 1	3180
November	1st to 10th	Day	19% 53% 7% 10% 10% 1	1851
	11th to 20th	Day	15% 54% 4 12% 13% 2	1890
	21st to end	Day	18% 54% 6% 15% 6% 1	1890
December	1st to 10th	Day	27% 34% 10% 20% 9%	2730
	11th to 20th	Day	31% 30% 7% 14% 16% 3	3066
	21st to end	Day	38% 25% 4 17% 13% 2	4048
January	1st to 10th	Night	27% 25% 5% 23% 17% 2	6489
	11th to 20th	Night	33% 25% 8% 16% 14% 4	6500
	21st to end	Night	40% 26% 6% 14% 11% 3	7035
February	1st to 10th	Night	19% 61% 5% 10% 3 1	2480
	11th to 20th	Night	18% 60% 2 9% 9% 1	2340
	21st to end	Night	20% 61% 2 8% 7% 2	1980
March	1st to 10th	Night	37% 28% 7% 13% 9% 6%	5374
	11th to 20th	Night	34% 28% 9% 18% 9% 2	5305
	21st to end	Night	39% 28% 3 8% 18% 4	4972
April	1st to 10th	Night	20% 61% 3 8% 6% 2	2000
	11th to 20th	Night	16% 62% 5% 8% 8% 1	1975
	21st to end	Night	18% 61% 3 9% 8% 1	1878
May	1st to 10th	Night	45% 28% 12% 9% 5% 1	4060
	11th to 20th	Night	42% 27% 11% 12% 6% 2	3949
	21st to end	Night	42% 27% 8% 16% 6% 1	3927
June	1st to 10th	Night	18% 61% 2 9% 9% 1	1600
	11th to 20th	Night	16% 62% 4 11% 7%	1600
	21st to end	Night	16% 60% 4 11% 7% 1	1600
July	1st to 10th	Night	41% 27% 6% 16% 9%	3560
	11th to 20th	Night	42% 26% 12% 14% 6%	3552
	21st to end	Night	33% 25% 11% 19% 12%	3809
August	1st to 10th	Night	38% 36% 10% 11% 5% 1	2797
	11th to 20th	Night	26% 36% 12% 21% 5%	3185
	21st to end	Night	14% 35% 9% 25% 15% 1	3586
September	1st to 10th	Night	18% 57% 5% 14% 7% 1	2000
	11th to 20th	Night	16% 56% 3 10% 12% 2	2161
	21st to end	Night	24% 57% 4 8% 6% 1	2200
October	1st to 10th	Night	25% 35% 7% 19% 13% 2	3590
	11th to 20th	Night	14% 35% 5% 17% 27% 4	3941
	21st to end	Night	17% 35% 9% 20% 17% 2	4610
November	1st to 10th	Night	19% 53% 5% 12% 10% 1	2667
	11th to 20th	Night	18% 54% 3 10% 12% 3	2730
	21st to end	Night	18% 54% 5% 15% 6% 1	2730
December	1st to 10th	Night	28% 34% 7% 22% 8% 1	4652
	11th to 20th	Night	35% 30% 5% 18% 11% 2	5348
	21st to end	Night	35% 25% 7% 14% 16% 3	7150

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	22% 21% 37% 15% 3 1	220
	11th to 20th	Day	25% 25% 34% 14% 3	220
	21st to end	Day	23% 20% 37% 13% 5% 1	267
February	1st to 10th	Day	23% 17% 38% 17% 4	419
	11th to 20th	Day	27% 21% 37% 14% 2	496
	21st to end	Day	26% 17% 35% 17% 3 1	414
March	1st to 10th	Day	21% 21% 35% 19% 4	500
	11th to 20th	Day	20% 15% 40% 19% 5% 1	500
	21st to end	Day	26% 14% 36% 17% 6% 1	550
April	1st to 10th	Day	26% 16% 34% 18% 6% 1	500
	11th to 20th	Day	24% 15% 32% 20% 8% 1	492
	21st to end	Day	24% 12% 32% 23% 6% 2	500
May	1st to 10th	Day	27% 12% 32% 20% 7% 2	503
	11th to 20th	Day	20% 8% 36% 26% 9% 1	527
	21st to end	Day	20% 6% 24% 30% 16% 5%	573
June	1st to 10th	Day	17% 5% 28% 32% 15% 3	530
	11th to 20th	Day	17% 5% 28% 31% 16% 4	530
	21st to end	Day	15% 4 25% 34% 18% 4	530
July	1st to 10th	Day	17% 3 21% 34% 21% 5%	525
	11th to 20th	Day	11% 5% 20% 34% 22% 8%	524
	21st to end	Day	14% 5% 23% 35% 19% 3	576
August	1st to 10th	Day	14% 3 20% 35% 21% 7%	526
	11th to 20th	Day	15% 2 19% 34% 22% 8%	519
	21st to end	Day	11% 3 26% 33% 17% 10%	583
September	1st to 10th	Day	20% 5% 21% 30% 16% 8%	530
	11th to 20th	Day	14% 4 26% 25% 19% 12%	530
	21st to end	Day	22% 6% 30% 24% 15% 3	530
October	1st to 10th	Day	22% 7% 24% 23% 16% 7%	530
	11th to 20th	Day	15% 13% 31% 21% 16% 3	513
	21st to end	Day	24% 11% 33% 20% 9% 3	462
November	1st to 10th	Day	16% 14% 32% 26% 11% 2	425
	11th to 20th	Day	19% 22% 30% 20% 8%	430
	21st to end	Day	22% 21% 27% 21% 8% 1	430
December	1st to 10th	Day	19% 22% 37% 14% 7%	257
	11th to 20th	Day	30% 25% 26% 15% 3	220
	21st to end	Day	26% 16% 33% 16% 7% 2	242
January	1st to 10th	Night	22% 23% 33% 17% 5%	840
	11th to 20th	Night	28% 19% 29% 20% 4	840
	21st to end	Night	20% 22% 34% 21% 2	924
February	1st to 10th	Night	23% 14% 38% 22% 3	801
	11th to 20th	Night	27% 20% 35% 15% 2	783
	21st to end	Night	25% 18% 33% 19% 5%	660
March	1st to 10th	Night	23% 16% 33% 22% 5%	800
	11th to 20th	Night	23% 12% 34% 24% 5% 2	800
	21st to end	Night	22% 13% 35% 22% 7% 1	880
April	1st to 10th	Night	26% 11% 31% 26% 6%	800
	11th to 20th	Night	21% 10% 31% 29% 8% 1	791
	21st to end	Night	21% 8% 32% 28% 9% 1	678
May	1st to 10th	Night	24% 7% 27% 29% 12% 2	600
	11th to 20th	Night	24% 6% 32% 30% 8% 1	559
	21st to end	Night	22% 2 18% 36% 20% 2	433
June	1st to 10th	Night	21% 3 24% 31% 19% 2	400
	11th to 20th	Night	22% 3 17% 37% 20% 2	400
	21st to end	Night	16% 4 17% 40% 21% 2	400
July	1st to 10th	Night	14% 2 14% 42% 25% 3	390
	11th to 20th	Night	13% 4 15% 39% 23% 5%	388
	21st to end	Night	14% 3 15% 44% 23% 2	438
August	1st to 10th	Night	11% 2 16% 44% 24% 2	528
	11th to 20th	Night	13% 3 15% 37% 27% 6%	761
	21st to end	Night	13% 4 14% 37% 26% 6%	880
September	1st to 10th	Night	16% 3 20% 33% 22% 6%	800
	11th to 20th	Night	16% 3 18% 32% 23% 8%	800
	21st to end	Night	22% 5% 21% 30% 18% 3	800
October	1st to 10th	Night	22% 8% 23% 25% 18% 5%	800
	11th to 20th	Night	22% 11% 26% 27% 13% 2	800
	21st to end	Night	24% 10% 31% 23% 10% 1	880
November	1st to 10th	Night	17% 11% 30% 26% 13% 2	820
	11th to 20th	Night	24% 20% 26% 21% 9% 1	840
	21st to end	Night	20% 20% 29% 24% 8% 1	840
December	1st to 10th	Night	25% 18% 29% 21% 5% 1	840
	11th to 20th	Night	24% 22% 29% 21% 4	840
	21st to end	Night	26% 16% 33% 20% 4	924

Page generated at 2026-01-29 01:21:41. Version ac07

Copyright © 2026 Attilla Danko.