Long Point, Glenn County
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Long Point, Glenn County clear sky chart from 2005-11-06 to 2025-02-06.

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	5% 4 1 3 3 3 3 3 4 6% 65%	112616
	Night	5% 4 1 3 3 3 3 3 5% 6% 64%	114445
Transparency	Day	21% 3 9% 19% 25% 22%	112371
	Night	22% 4 11% 19% 24% 20%	114279
Seeing	Day	10% 11% 27% 31% 17% 5%	15447
	Night	8% 7% 25% 32% 23% 6%	24761

By Month

Percentage Cloud Cover SW (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	6% 5% 2 5% 5% 4 6% 4 7% 9% 49%	3708
	11th to 20th	Day	7% 7% 2 5% 4 3 3 2 4 5% 56%	4100
	21st to end	Day	11% 8% 2 5% 3 4 4 3 4 6% 52%	4510
February	1st to 10th	Day	9% 6% 1 5% 4 5% 5% 5% 5% 6% 48%	1756
	11th to 20th	Day	6% 6% 2 6% 4 5% 4 4 5% 9% 48%	1677
	21st to end	Day	8% 6% 2 5% 4 4 4 4 5% 8% 50%	1570
March	1st to 10th	Day	9% 11% 4 9% 6% 6% 4 4 6% 6% 35%	3403
	11th to 20th	Day	5% 4 2 4 3 3 4 3 5% 6% 59%	3490
	21st to end	Day	9% 9% 3 7% 5% 5% 5% 4 6% 7% 39%	3853
April	1st to 10th	Day	8% 6% 2 7% 5% 3 4 4 6% 9% 45%	2280
	11th to 20th	Day	7% 6% 2 5% 2 5% 4 3 6% 6% 55%	2249
	21st to end	Day	3 4 1 3 3 3 4 4 5% 9% 60%	2285
May	1st to 10th	Day	3 3 1 2 2 2 3 2 4 6% 72%	4110
	11th to 20th	Day	2 2 1 2 2 2 2 2 4 5% 75%	4253
	21st to end	Day	3 2 1 2 1 2 3 3 4 7% 71%	4813
June	1st to 10th	Day	3 4 1 4 2 3 4 4 6% 8% 61%	2660
	11th to 20th	Day	1 1 1 2 2 2 3 2 5% 6% 75%	2660
	21st to end	Day	2 1 1 2 2 1 2 2 3 4 81%	2660
July	1st to 10th	Day	1 1 1 1 1 1 2 2 91%	4420
	11th to 20th	Day	1 1 2 1 2 1 1 2 3 85%	4277
	21st to end	Day	1 1 1 1 1 1 2 3 90%	4455
August	1st to 10th	Day	1 1 1 2 1 1 2 2 4 6% 79%	4091
	11th to 20th	Day	1 1 1 1 1 1 2 3 91%	3964
	21st to end	Day	1 1 1 2 2 2 1 1 2 3 86%	4180
September	1st to 10th	Day	1 1 1 1 1 1 2 3 88%	2280
	11th to 20th	Day	2 2 1 2 2 2 3 2 4 5% 75%	2275
	21st to end	Day	1 1 1 2 2 1 1 2 3 5% 81%	2000
October	1st to 10th	Day	2 1 1 1 1 2 2 2 4 5% 79%	3180
	11th to 20th	Day	4 2 1 2 2 3 2 2 4 7% 73%	3161
	21st to end	Day	4 2 1 3 2 4 5% 4 6% 8% 60%	3448
November	1st to 10th	Day	5% 5% 2 4 3 3 4 4 6% 8% 56%	1886
	11th to 20th	Day	6% 6% 1 5% 4 4 4 4 6% 9% 51%	1710
	21st to end	Day	6% 4 1 4 3 4 5% 5% 6% 7% 56%	1600
December	1st to 10th	Day	5% 3 1 4 3 3 4 4 7% 8% 58%	2620
	11th to 20th	Day	16% 10% 3 7% 5% 5% 5% 4 6% 9% 31%	3028
	21st to end	Day	11% 8% 2 7% 5% 6% 6% 4 6% 8% 36%	4004
January	1st to 10th	Night	6% 4 1 4 4 4 5% 6% 8% 10% 49%	6235
	11th to 20th	Night	7% 5% 2 5% 4 3 4 3 4 6% 57%	5880
	21st to end	Night	10% 6% 2 5% 4 4 4 3 4 5% 52%	6468
February	1st to 10th	Night	7% 6% 2 5% 5% 4 4 4 6% 7% 50%	2535
	11th to 20th	Night	6% 4 2 4 4 4 5% 4 7% 9% 50%	2388
	21st to end	Night	6% 5% 1 6% 4 4 4 4 5% 7% 55%	1884
March	1st to 10th	Night	7% 7% 2 5% 5% 5% 5% 5% 7% 9% 44%	3468
	11th to 20th	Night	4 5% 1 4 3 3 3 3 5% 5% 63%	3490
	21st to end	Night	7% 6% 2 5% 5% 4 5% 5% 7% 8% 47%	3798
April	1st to 10th	Night	7% 5% 1 4 5% 4 4 3 5% 7% 53%	1900
	11th to 20th	Night	5% 4 1 4 3 3 4 4 6% 7% 60%	1879
	21st to end	Night	3 4 1 2 2 2 3 3 5% 7% 68%	1891
May	1st to 10th	Night	4 2 1 2 2 2 3 2 3 4 75%	2860
	11th to 20th	Night	1 1 1 2 1 2 2 4 4 81%	2628
	21st to end	Night	2 2 1 1 2 3 2 3 5% 78%	2762
June	1st to 10th	Night	5% 3 1 3 3 2 3 3 5% 7% 64%	1520
	11th to 20th	Night	2 1 1 2 1 2 2 2 2 5% 81%	1520
	21st to end	Night	1 1 1 2 1 2 2 3 4 83%	1520
July	1st to 10th	Night	1 1 1 1 1 2 93%	2540
	11th to 20th	Night	1 1 1 1 1 1 1 2 2 88%	2685
	21st to end	Night	1 1 1 1 1 2 2 91%	3109
August	1st to 10th	Night	2 1 1 1 1 2 2 2 3 2 82%	2848
	11th to 20th	Night	1 1 1 1 1 2 92%	2876
	21st to end	Night	2 1 1 1 1 1 1 2 2 89%	3498
September	1st to 10th	Night	1 1 1 1 1 1 2 3 90%	1900
	11th to 20th	Night	2 2 1 1 1 2 2 2 3 5% 79%	1901
	21st to end	Night	1 1 1 1 1 2 2 3 5% 83%	2180
October	1st to 10th	Night	2 1 1 1 1 2 3 2 2 4 81%	3800
	11th to 20th	Night	2 1 1 2 1 2 3 2 3 6% 76%	3777
	21st to end	Night	4 2 1 2 2 3 4 3 6% 8% 65%	4121
November	1st to 10th	Night	4 3 1 3 4 4 5% 4 6% 7% 58%	2410
	11th to 20th	Night	6% 3 1 4 3 4 5% 4 7% 9% 53%	2686
	21st to end	Night	5% 3 2 4 3 3 5% 5% 6% 8% 57%	2800
December	1st to 10th	Night	6% 4 1 4 3 3 3 3 5% 8% 61%	4560
	11th to 20th	Night	15% 7% 2 6% 3 4 5% 5% 7% 10% 35%	5176
	21st to end	Night	11% 8% 3 8% 5% 6% 6% 4 5% 6% 37%	6952

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	33% 8% 18% 21% 13% 7%	3708
	11th to 20th	Day	32% 4 10% 15% 22% 16%	4100
	21st to end	Day	36% 4 9% 14% 19% 18%	4510
February	1st to 10th	Day	36% 5% 13% 18% 18% 9%	1756
	11th to 20th	Day	35% 4 11% 22% 21% 7%	1686
	21st to end	Day	33% 5% 15% 25% 17% 5%	1570
March	1st to 10th	Day	49% 5% 12% 14% 16% 4	3403
	11th to 20th	Day	27% 4 11% 23% 24% 11%	3490
	21st to end	Day	42% 6% 19% 20% 11% 2	3853
April	1st to 10th	Day	36% 5% 17% 21% 18% 3	2280
	11th to 20th	Day	29% 4 15% 25% 21% 6%	2252
	21st to end	Day	21% 4 18% 29% 22% 6%	2285
May	1st to 10th	Day	15% 3 13% 26% 25% 18%	4110
	11th to 20th	Day	13% 2 7% 19% 40% 19%	4256
	21st to end	Day	13% 4 13% 34% 27% 9%	4814
June	1st to 10th	Day	20% 5% 14% 27% 25% 8%	2660
	11th to 20th	Day	11% 3 10% 20% 37% 19%	2660
	21st to end	Day	10% 2 4 18% 34% 33%	2660
July	1st to 10th	Day	4 1 2 8% 18% 66%	4351
	11th to 20th	Day	8% 1 3 8% 21% 59%	4202
	21st to end	Day	4 2 1 10% 30% 53%	4315
August	1st to 10th	Day	9% 1 2 11% 31% 45%	4076
	11th to 20th	Day	4 1 2 19% 40% 34%	4003
	21st to end	Day	8% 1 2 20% 39% 29%	4179
September	1st to 10th	Day	5% 1 2 11% 30% 51%	2280
	11th to 20th	Day	12% 3 6% 25% 36% 17%	2275
	21st to end	Day	10% 2 8% 19% 34% 28%	2000
October	1st to 10th	Day	11% 2 3 15% 24% 44%	3180
	11th to 20th	Day	16% 2 7% 27% 31% 17%	3161
	21st to end	Day	24% 3 9% 21% 32% 12%	3448
November	1st to 10th	Day	26% 4 13% 26% 21% 11%	1886
	11th to 20th	Day	30% 6% 16% 20% 18% 10%	1710
	21st to end	Day	26% 5% 13% 20% 20% 15%	1600
December	1st to 10th	Day	24% 4 10% 19% 28% 14%	2620
	11th to 20th	Day	50% 3 11% 17% 15% 3	3028
	21st to end	Day	42% 5% 19% 18% 13% 3	4004
January	1st to 10th	Night	30% 7% 22% 20% 17% 4	6235
	11th to 20th	Night	29% 4 13% 17% 23% 13%	5880
	21st to end	Night	36% 4 9% 11% 16% 24%	6468
February	1st to 10th	Night	34% 4 13% 19% 21% 10%	2535
	11th to 20th	Night	30% 6% 13% 21% 21% 8%	2390
	21st to end	Night	29% 5% 15% 28% 18% 6%	1884
March	1st to 10th	Night	35% 6% 23% 17% 15% 3	3468
	11th to 20th	Night	24% 4 11% 23% 28% 9%	3490
	21st to end	Night	33% 6% 24% 23% 11% 3	3798
April	1st to 10th	Night	30% 5% 20% 21% 18% 6%	1900
	11th to 20th	Night	23% 6% 17% 25% 20% 8%	1879
	21st to end	Night	18% 3 17% 33% 24% 6%	1891
May	1st to 10th	Night	16% 2 10% 27% 29% 15%	2860
	11th to 20th	Night	8% 2 10% 20% 38% 22%	2628
	21st to end	Night	10% 4 13% 38% 25% 10%	2762
June	1st to 10th	Night	20% 5% 14% 26% 28% 8%	1520
	11th to 20th	Night	10% 2 9% 22% 36% 21%	1520
	21st to end	Night	8% 2 5% 17% 33% 35%	1520
July	1st to 10th	Night	3 1 2 10% 16% 68%	2500
	11th to 20th	Night	6% 1 3 9% 17% 64%	2637
	21st to end	Night	3 1 1 8% 33% 53%	3011
August	1st to 10th	Night	11% 1 1 10% 29% 47%	2839
	11th to 20th	Night	3 1 2 11% 40% 44%	2903
	21st to end	Night	6% 1 2 16% 41% 33%	3498
September	1st to 10th	Night	4 1 3 11% 27% 54%	1900
	11th to 20th	Night	11% 3 6% 20% 36% 24%	1901
	21st to end	Night	8% 2 7% 21% 28% 34%	2180
October	1st to 10th	Night	11% 2 4 13% 22% 49%	3800
	11th to 20th	Night	12% 3 7% 28% 34% 15%	3777
	21st to end	Night	18% 2 8% 24% 29% 19%	4121
November	1st to 10th	Night	25% 4 16% 24% 18% 13%	2410
	11th to 20th	Night	27% 5% 18% 23% 18% 9%	2686
	21st to end	Night	25% 5% 15% 19% 22% 14%	2800
December	1st to 10th	Night	24% 4 8% 20% 27% 17%	4560
	11th to 20th	Night	45% 5% 12% 19% 17% 3	5176
	21st to end	Night	45% 7% 13% 19% 12% 4	6952

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% 14% 33% 19% 10% 2	230
	11th to 20th	Day	15% 15% 35% 23% 10% 3	400
	21st to end	Day	15% 16% 28% 23% 14% 3	440
February	1st to 10th	Day	18% 16% 29% 24% 10% 3	386
	11th to 20th	Day	16% 20% 30% 24% 9% 1	371
	21st to end	Day	13% 20% 34% 24% 8% 1	382
March	1st to 10th	Day	25% 19% 35% 15% 5% 1	460
	11th to 20th	Day	17% 19% 30% 23% 9% 1	460
	21st to end	Day	18% 22% 35% 20% 6%	506
April	1st to 10th	Day	15% 18% 35% 22% 8% 2	460
	11th to 20th	Day	20% 15% 27% 28% 8% 2	452
	21st to end	Day	8% 16% 33% 27% 12% 3	460
May	1st to 10th	Day	10% 18% 31% 25% 13% 3	463
	11th to 20th	Day	9% 13% 26% 32% 14% 6%	488
	21st to end	Day	11% 9% 25% 30% 18% 6%	529
June	1st to 10th	Day	5% 10% 25% 37% 18% 6%	490
	11th to 20th	Day	6% 12% 31% 31% 18% 3	490
	21st to end	Day	2 7% 23% 38% 22% 8%	490
July	1st to 10th	Day	2 2 23% 44% 21% 7%	486
	11th to 20th	Day	1 4 19% 41% 25% 10%	484
	21st to end	Day	1 4 18% 43% 25% 9%	531
August	1st to 10th	Day	2 5% 23% 37% 22% 11%	487
	11th to 20th	Day	2 5% 22% 36% 25% 9%	477
	21st to end	Day	2 3 20% 41% 28% 6%	539
September	1st to 10th	Day	2 4 22% 43% 23% 5%	490
	11th to 20th	Day	3 6% 21% 41% 24% 5%	490
	21st to end	Day	3 8% 25% 36% 21% 6%	490
October	1st to 10th	Day	6% 8% 28% 32% 19% 6%	490
	11th to 20th	Day	8% 8% 23% 30% 25% 6%	490
	21st to end	Day	11% 11% 22% 33% 18% 5%	539
November	1st to 10th	Day	10% 11% 28% 27% 19% 5%	422
	11th to 20th	Day	11% 7% 32% 23% 20% 8%	255
	21st to end	Day	16% 9% 24% 25% 21% 6%	200
December	1st to 10th	Day	12% 14% 27% 23% 16% 9%	200
	11th to 20th	Day	18% 11% 30% 22% 15% 6%	200
	21st to end	Day	16% 16% 26% 24% 15% 3	220
January	1st to 10th	Night	14% 7% 29% 28% 16% 6%	800
	11th to 20th	Night	13% 8% 29% 31% 14% 5%	800
	21st to end	Night	13% 5% 31% 29% 17% 5%	880
February	1st to 10th	Night	14% 8% 28% 32% 15% 3	780
	11th to 20th	Night	10% 10% 29% 30% 15% 5%	744
	21st to end	Night	11% 10% 32% 34% 11% 2	628
March	1st to 10th	Night	15% 11% 31% 25% 13% 4	760
	11th to 20th	Night	10% 11% 29% 29% 19% 2	760
	21st to end	Night	11% 13% 33% 28% 13% 2	836
April	1st to 10th	Night	12% 9% 31% 31% 13% 4	760
	11th to 20th	Night	11% 11% 30% 28% 15% 5%	751
	21st to end	Night	5% 9% 33% 30% 18% 4	751
May	1st to 10th	Night	6% 7% 36% 27% 20% 3	570
	11th to 20th	Night	3 5% 27% 37% 24% 4	447
	21st to end	Night	4 9% 24% 29% 28% 6%	411
June	1st to 10th	Night	6% 7% 22% 38% 24% 3	380
	11th to 20th	Night	3 9% 25% 38% 23% 2	380
	21st to end	Night	2 2 23% 42% 27% 4	380
July	1st to 10th	Night	1 14% 44% 38% 5%	370
	11th to 20th	Night	1 1 15% 36% 40% 8%	448
	21st to end	Night	9% 33% 45% 12%	624
August	1st to 10th	Night	3 12% 32% 43% 10%	567
	11th to 20th	Night	1 2 15% 35% 37% 10%	602
	21st to end	Night	2 1 9% 35% 44% 8%	836
September	1st to 10th	Night	1 2 15% 39% 35% 8%	760
	11th to 20th	Night	3 3 13% 36% 34% 10%	760
	21st to end	Night	2 4 21% 35% 28% 10%	760
October	1st to 10th	Night	4 6% 21% 39% 23% 7%	760
	11th to 20th	Night	4 5% 21% 36% 26% 8%	760
	21st to end	Night	8% 6% 22% 29% 24% 10%	836
November	1st to 10th	Night	7% 8% 23% 30% 25% 7%	780
	11th to 20th	Night	9% 5% 29% 35% 18% 4	800
	21st to end	Night	7% 7% 32% 31% 18% 5%	800
December	1st to 10th	Night	13% 5% 26% 33% 17% 6%	800
	11th to 20th	Night	14% 8% 31% 28% 16% 4	800
	21st to end	Night	12% 11% 32% 29% 13% 3	880

Page generated at 2025-02-03 00:05:51. Version ac07

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