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 2024-11-28.

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%	101390
	Night	18% 8% 3 6% 4 4 4 3 5% 7% 39%	98165
Transparency	Day	24% 46% 7% 13% 9% 1	104952
	Night	25% 45% 6% 13% 9% 1	102692
Seeing	Day	20% 11% 29% 25% 12% 4	15193
	Night	21% 11% 27% 27% 12% 2	24224

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	16% 8% 2 5% 4 4 4 3 5% 7% 42%	2517
	11th to 20th	Day	17% 8% 2 6% 4 5% 5% 4 5% 6% 38%	2520
	21st to end	Day	21% 11% 3 7% 5% 4 4 3 5% 5% 32%	2840
February	1st to 10th	Day	18% 6% 3 6% 4 5% 5% 3 6% 7% 37%	1823
	11th to 20th	Day	16% 6% 2 6% 5% 4 3 3 5% 6% 44%	1848
	21st to end	Day	20% 9% 2 7% 4 3 3 4 5% 7% 36%	1570
March	1st to 10th	Day	26% 8% 2 5% 3 3 3 3 5% 6% 37%	3116
	11th to 20th	Day	10% 4 2 4 4 4 4 4 6% 8% 51%	3251
	21st to end	Day	20% 9% 3 5% 3 3 3 3 5% 6% 40%	4153
April	1st to 10th	Day	18% 8% 2 5% 4 4 3 3 5% 5% 41%	2280
	11th to 20th	Day	18% 6% 2 5% 4 3 4 3 5% 7% 44%	2254
	21st to end	Day	19% 6% 2 5% 3 4 4 4 6% 6% 41%	2394
May	1st to 10th	Day	26% 11% 3 6% 3 4 3 3 5% 6% 30%	4106
	11th to 20th	Day	23% 8% 3 7% 4 3 3 3 4 6% 35%	4166
	21st to end	Day	13% 7% 2 5% 3 3 4 3 6% 9% 43%	4837
June	1st to 10th	Day	16% 6% 1 5% 4 4 4 4 6% 9% 41%	2660
	11th to 20th	Day	12% 7% 2 6% 4 3 5% 4 6% 9% 41%	2660
	21st to end	Day	11% 6% 2 5% 4 5% 4 4 7% 9% 44%	2660
July	1st to 10th	Day	12% 9% 3 8% 5% 4 5% 5% 6% 8% 35%	4440
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 6% 9% 41%	4440
	21st to end	Day	16% 8% 3 7% 5% 3 5% 4 6% 8% 36%	4814
August	1st to 10th	Day	16% 7% 2 6% 4 4 5% 4 6% 9% 36%	4178
	11th to 20th	Day	10% 6% 2 6% 4 4 5% 3 5% 8% 47%	3768
	21st to end	Day	7% 3 2 4 4 4 4 5% 6% 10% 51%	4180
September	1st to 10th	Day	14% 6% 2 6% 4 3 3 3 5% 7% 47%	2280
	11th to 20th	Day	11% 6% 2 4 3 4 3 3 5% 6% 53%	2126
	21st to end	Day	19% 6% 2 6% 4 4 4 4 5% 7% 39%	2090
October	1st to 10th	Day	21% 5% 2 5% 3 3 3 2 5% 7% 44%	2090
	11th to 20th	Day	14% 5% 2 5% 3 3 4 4 5% 7% 47%	1882
	21st to end	Day	18% 6% 3 5% 5% 4 4 3 5% 7% 40%	1881
November	1st to 10th	Day	14% 7% 1 5% 4 3 3 3 5% 5% 50%	1761
	11th to 20th	Day	15% 6% 2 5% 4 3 3 3 4 7% 47%	1800
	21st to end	Day	15% 8% 2 4 4 4 4 4 5% 6% 43%	1773
December	1st to 10th	Day	19% 7% 3 7% 4 4 4 4 5% 8% 35%	1554
	11th to 20th	Day	20% 8% 2 5% 4 3 3 3 4 5% 44%	1906
	21st to end	Day	19% 10% 4 8% 5% 4 4 3 4 6% 32%	2772
January	1st to 10th	Night	18% 6% 2 4 3 3 4 3 5% 7% 44%	4429
	11th to 20th	Night	18% 9% 3 7% 4 3 3 3 4 4 42%	4440
	21st to end	Night	24% 11% 3 8% 5% 4 4 3 4 5% 29%	4814
February	1st to 10th	Night	17% 9% 3 7% 5% 4 4 4 5% 7% 37%	2356
	11th to 20th	Night	19% 7% 2 6% 4 4 4 3 5% 8% 37%	2218
	21st to end	Night	20% 6% 2 6% 4 4 4 3 4 5% 40%	1884
March	1st to 10th	Night	25% 12% 3 6% 3 3 2 2 4 5% 35%	3724
	11th to 20th	Night	12% 7% 2 6% 5% 4 4 3 5% 7% 45%	3706
	21st to end	Night	23% 9% 3 5% 3 3 4 3 5% 6% 38%	3476
April	1st to 10th	Night	19% 9% 2 5% 5% 4 4 3 5% 7% 39%	1900
	11th to 20th	Night	19% 7% 3 6% 4 4 4 3 5% 6% 42%	1875
	21st to end	Night	20% 8% 2 6% 4 3 3 3 4 6% 40%	1784
May	1st to 10th	Night	23% 14% 4 7% 4 4 3 3 4 6% 27%	2834
	11th to 20th	Night	26% 9% 3 7% 4 4 4 4 5% 7% 27%	2756
	21st to end	Night	17% 9% 3 6% 4 4 4 4 7% 7% 35%	2738
June	1st to 10th	Night	17% 8% 3 6% 4 4 4 3 4 8% 38%	1520
	11th to 20th	Night	16% 6% 2 5% 4 4 3 3 6% 9% 41%	1520
	21st to end	Night	12% 7% 2 7% 5% 5% 5% 5% 6% 9% 37%	1520
July	1st to 10th	Night	13% 12% 4 8% 5% 4 5% 5% 6% 8% 31%	2520
	11th to 20th	Night	12% 7% 2 7% 6% 5% 4 5% 8% 10% 34%	2520
	21st to end	Night	19% 8% 2 6% 5% 5% 4 3 6% 9% 32%	2739
August	1st to 10th	Night	21% 7% 3 6% 4 5% 5% 5% 6% 8% 30%	2720
	11th to 20th	Night	10% 7% 2 7% 5% 5% 6% 4 6% 9% 39%	3057
	21st to end	Night	7% 4 2 5% 4 3 4 4 6% 9% 54%	3476
September	1st to 10th	Night	15% 6% 2 6% 4 5% 5% 4 5% 6% 43%	1900
	11th to 20th	Night	14% 6% 2 4 3 2 3 3 5% 7% 51%	2053
	21st to end	Night	18% 8% 2 7% 5% 4 4 3 5% 6% 39%	2090
October	1st to 10th	Night	20% 8% 3 6% 4 3 4 3 3 6% 40%	2090
	11th to 20th	Night	16% 6% 2 5% 3 3 3 3 4 6% 48%	2296
	21st to end	Night	20% 8% 3 7% 4 4 3 2 4 6% 40%	2717
November	1st to 10th	Night	14% 6% 3 6% 3 4 5% 3 4 6% 46%	2537
	11th to 20th	Night	19% 7% 2 5% 4 4 3 3 5% 5% 45%	2600
	21st to end	Night	15% 5% 2 5% 5% 4 4 4 6% 8% 42%	2562
December	1st to 10th	Night	20% 9% 3 6% 5% 4 4 3 5% 7% 34%	2622
	11th to 20th	Night	19% 8% 3 6% 4 4 3 3 5% 7% 39%	3288
	21st to end	Night	20% 10% 3 7% 4 4 3 3 4 6% 36%	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	29% 37% 4 19% 9% 1	2518
	11th to 20th	Day	28% 38% 6% 19% 8% 1	2520
	21st to end	Day	39% 38% 5% 13% 4 1	2840
February	1st to 10th	Day	17% 65% 7% 7% 3	1823
	11th to 20th	Day	16% 63% 2 9% 9% 1	1857
	21st to end	Day	17% 65% 5% 7% 5% 2	1570
March	1st to 10th	Day	35% 40% 5% 11% 7% 1	3119
	11th to 20th	Day	15% 39% 9% 26% 10% 1	3251
	21st to end	Day	30% 39% 4 11% 12% 4	4153
April	1st to 10th	Day	18% 65% 3 7% 6% 1	2280
	11th to 20th	Day	15% 65% 3 8% 9%	2254
	21st to end	Day	15% 65% 3 10% 7% 1	2394
May	1st to 10th	Day	39% 39% 10% 7% 4 1	4120
	11th to 20th	Day	36% 39% 11% 11% 3	4170
	21st to end	Day	25% 39% 6% 17% 13% 1	4837
June	1st to 10th	Day	15% 65% 4 9% 8%	2660
	11th to 20th	Day	13% 65% 5% 9% 7% 1	2660
	21st to end	Day	12% 63% 5% 10% 9%	2660
July	1st to 10th	Day	34% 37% 7% 10% 11% 1	4370
	11th to 20th	Day	28% 36% 13% 14% 8%	4365
	21st to end	Day	34% 36% 9% 12% 9% 2	4661
August	1st to 10th	Day	34% 37% 10% 15% 4	4164
	11th to 20th	Day	24% 37% 11% 24% 4	3805
	21st to end	Day	15% 36% 12% 24% 13% 1	4180
September	1st to 10th	Day	16% 60% 6% 11% 8%	2280
	11th to 20th	Day	15% 60% 3 10% 11% 1	2126
	21st to end	Day	21% 60% 4 8% 7%	2090
October	1st to 10th	Day	21% 36% 7% 14% 17% 4	3480
	11th to 20th	Day	13% 36% 6% 16% 27% 2	3098
	21st to end	Day	18% 36% 10% 20% 15% 1	3081
November	1st to 10th	Day	18% 55% 7% 9% 9% 1	1761
	11th to 20th	Day	14% 56% 4 12% 13% 2	1800
	21st to end	Day	16% 58% 6% 14% 5% 2	1773
December	1st to 10th	Day	21% 59% 6% 6% 8%	1554
	11th to 20th	Day	23% 47% 6% 8% 14% 1	1906
	21st to end	Day	36% 37% 5% 16% 6%	2772
January	1st to 10th	Night	26% 36% 6% 23% 7% 3	4429
	11th to 20th	Night	29% 36% 8% 16% 10% 1	4440
	21st to end	Night	43% 38% 4 10% 5% 1	4814
February	1st to 10th	Night	17% 65% 5% 9% 3 1	2356
	11th to 20th	Night	17% 64% 2 8% 9% 1	2220
	21st to end	Night	18% 64% 2 8% 6% 2	1884
March	1st to 10th	Night	39% 39% 3 12% 5% 1	3734
	11th to 20th	Night	21% 39% 8% 18% 11% 2	3707
	21st to end	Night	33% 39% 3 7% 14% 4	3476
April	1st to 10th	Night	18% 64% 3 8% 6% 1	1900
	11th to 20th	Night	14% 65% 5% 8% 7% 1	1875
	21st to end	Night	17% 64% 3 9% 6% 1	1784
May	1st to 10th	Night	40% 39% 8% 9% 3	2840
	11th to 20th	Night	40% 39% 10% 8% 3	2757
	21st to end	Night	31% 39% 7% 15% 8% 1	2739
June	1st to 10th	Night	16% 65% 2 9% 8% 1	1520
	11th to 20th	Night	13% 65% 4 11% 6%	1520
	21st to end	Night	14% 63% 4 11% 7% 1	1520
July	1st to 10th	Night	38% 37% 5% 11% 9%	2480
	11th to 20th	Night	30% 37% 13% 15% 5%	2472
	21st to end	Night	36% 35% 10% 9% 10% 1	2651
August	1st to 10th	Night	38% 38% 10% 10% 4 1	2710
	11th to 20th	Night	26% 37% 12% 21% 4	3086
	21st to end	Night	14% 36% 9% 26% 15%	3476
September	1st to 10th	Night	16% 59% 5% 12% 7% 1	1900
	11th to 20th	Night	15% 59% 3 9% 11% 2	2053
	21st to end	Night	23% 60% 3 8% 6% 1	2090
October	1st to 10th	Night	25% 36% 7% 18% 12% 2	3480
	11th to 20th	Night	12% 36% 5% 16% 27% 4	3819
	21st to end	Night	17% 36% 9% 19% 17% 2	4467
November	1st to 10th	Night	18% 56% 5% 11% 9% 1	2537
	11th to 20th	Night	17% 57% 3 9% 11% 3	2600
	21st to end	Night	17% 57% 5% 14% 6% 1	2562
December	1st to 10th	Night	22% 59% 4 9% 5%	2622
	11th to 20th	Night	24% 48% 5% 10% 12% 1	3288
	21st to end	Night	34% 37% 7% 14% 9%	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	25% 18% 37% 16% 4 1	180
	11th to 20th	Day	27% 22% 33% 14% 3	180
	21st to end	Day	26% 16% 36% 15% 6% 1	218
February	1st to 10th	Day	24% 15% 38% 18% 5%	383
	11th to 20th	Day	25% 20% 38% 15% 2	456
	21st to end	Day	28% 18% 32% 18% 4 1	382
March	1st to 10th	Day	22% 19% 34% 20% 5%	460
	11th to 20th	Day	20% 16% 41% 18% 4 1	460
	21st to end	Day	25% 14% 35% 17% 7% 1	506
April	1st to 10th	Day	25% 16% 33% 18% 7% 1	460
	11th to 20th	Day	24% 14% 31% 22% 8% 1	452
	21st to end	Day	26% 12% 32% 23% 6% 2	460
May	1st to 10th	Day	27% 13% 31% 20% 8% 2	463
	11th to 20th	Day	21% 9% 34% 26% 9% 1	487
	21st to end	Day	19% 6% 24% 30% 17% 5%	529
June	1st to 10th	Day	16% 5% 28% 31% 16% 3	490
	11th to 20th	Day	15% 4 29% 31% 17% 4	490
	21st to end	Day	15% 4 26% 35% 17% 4	490
July	1st to 10th	Day	17% 4 20% 33% 21% 5%	485
	11th to 20th	Day	11% 5% 20% 35% 21% 9%	484
	21st to end	Day	15% 6% 24% 34% 19% 3	532
August	1st to 10th	Day	14% 4 20% 35% 22% 6%	486
	11th to 20th	Day	15% 2 19% 34% 22% 8%	479
	21st to end	Day	12% 4 24% 32% 18% 10%	539
September	1st to 10th	Day	20% 6% 19% 30% 16% 9%	490
	11th to 20th	Day	14% 4 27% 23% 19% 12%	490
	21st to end	Day	23% 6% 30% 23% 14% 3	490
October	1st to 10th	Day	23% 8% 24% 23% 16% 6%	490
	11th to 20th	Day	14% 13% 31% 22% 16% 3	475
	21st to end	Day	24% 10% 33% 21% 9% 3	429
November	1st to 10th	Day	16% 12% 31% 27% 11% 2	395
	11th to 20th	Day	20% 22% 30% 21% 9%	400
	21st to end	Day	21% 19% 28% 23% 9% 1	391
December	1st to 10th	Day	22% 22% 33% 14% 8%	214
	11th to 20th	Day	31% 24% 27% 16% 3	180
	21st to end	Day	28% 14% 35% 15% 6% 3	198
January	1st to 10th	Night	23% 21% 33% 18% 5%	760
	11th to 20th	Night	28% 18% 30% 20% 4	760
	21st to end	Night	22% 19% 35% 22% 2	836
February	1st to 10th	Night	23% 14% 38% 23% 3	760
	11th to 20th	Night	27% 19% 36% 16% 2	743
	21st to end	Night	26% 19% 32% 19% 5%	628
March	1st to 10th	Night	23% 15% 33% 23% 5%	760
	11th to 20th	Night	23% 13% 35% 24% 5% 1	760
	21st to end	Night	22% 13% 34% 23% 7% 1	836
April	1st to 10th	Night	25% 10% 31% 27% 7%	760
	11th to 20th	Night	21% 10% 30% 30% 8% 1	751
	21st to end	Night	21% 8% 32% 28% 9% 1	644
May	1st to 10th	Night	24% 7% 27% 29% 12% 2	570
	11th to 20th	Night	23% 7% 32% 30% 8%	531
	21st to end	Night	22% 2 16% 37% 21% 2	411
June	1st to 10th	Night	21% 3 23% 31% 19% 2	380
	11th to 20th	Night	21% 3 17% 36% 20% 2	380
	21st to end	Night	16% 4 17% 41% 20% 2	380
July	1st to 10th	Night	14% 2 14% 41% 25% 3	370
	11th to 20th	Night	12% 4 16% 39% 24% 5%	368
	21st to end	Night	14% 3 15% 43% 23% 2	416
August	1st to 10th	Night	11% 2 16% 45% 24% 3	501
	11th to 20th	Night	13% 3 15% 37% 26% 6%	722
	21st to end	Night	13% 3 13% 36% 27% 7%	836
September	1st to 10th	Night	17% 3 20% 33% 22% 6%	760
	11th to 20th	Night	17% 3 18% 30% 23% 9%	760
	21st to end	Night	22% 6% 22% 30% 18% 3	760
October	1st to 10th	Night	23% 8% 22% 25% 18% 4	760
	11th to 20th	Night	21% 10% 26% 28% 13% 2	760
	21st to end	Night	24% 10% 31% 23% 10% 1	836
November	1st to 10th	Night	16% 11% 31% 26% 13% 2	780
	11th to 20th	Night	24% 19% 26% 22% 9% 1	800
	21st to end	Night	20% 19% 30% 23% 7% 1	789
December	1st to 10th	Night	27% 17% 29% 21% 5% 1	760
	11th to 20th	Night	23% 22% 29% 22% 5%	760
	21st to end	Night	27% 15% 34% 21% 4	836

Page generated at 2024-11-25 00:22:21. Version ac07

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