HighBridge Hills Northern Lights Educational Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the HighBridge Hills Northern Lights Educational Center clear sky chart from 2005-11-06 to 2024-11-11.

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	14% 11% 4 9% 5% 4 5% 4 5% 6% 34%	101711
	Night	13% 12% 4 10% 5% 5% 5% 4 5% 6% 32%	97612
Transparency	Day	49% 7% 13% 21% 9% 1	105179
	Night	51% 7% 12% 20% 9% 1	102231
Seeing	Day	20% 18% 34% 19% 7% 2	16114
	Night	19% 15% 33% 24% 8% 1	25988

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	9% 17% 10% 20% 6% 5% 5% 3 4 5% 17%	2527
	11th to 20th	Day	7% 17% 6% 17% 10% 9% 9% 5% 5% 4 11%	2530
	21st to end	Day	9% 18% 8% 19% 7% 5% 5% 4 5% 5% 16%	2829
February	1st to 10th	Day	7% 14% 6% 13% 6% 5% 7% 4 4 5% 28%	1710
	11th to 20th	Day	8% 14% 5% 13% 8% 6% 6% 5% 4 5% 27%	1664
	21st to end	Day	11% 14% 7% 11% 8% 6% 5% 3 5% 6% 24%	1560
March	1st to 10th	Day	9% 12% 3 10% 5% 4 5% 4 5% 6% 36%	3118
	11th to 20th	Day	8% 15% 4 13% 6% 4 4 4 5% 7% 31%	3468
	21st to end	Day	18% 15% 4 14% 4 3 4 3 5% 5% 24%	4033
April	1st to 10th	Day	15% 18% 5% 9% 5% 4 4 3 4 6% 28%	2280
	11th to 20th	Day	20% 15% 5% 7% 4 3 4 3 4 5% 30%	2254
	21st to end	Day	20% 12% 4 8% 5% 4 3 4 4 5% 32%	2451
May	1st to 10th	Day	18% 10% 2 6% 3 4 4 3 4 5% 40%	4428
	11th to 20th	Day	15% 8% 2 6% 5% 5% 5% 4 6% 7% 38%	4399
	21st to end	Day	18% 8% 3 8% 5% 5% 4 4 5% 6% 33%	4837
June	1st to 10th	Day	13% 7% 2 6% 4 5% 4 4 6% 8% 40%	2660
	11th to 20th	Day	13% 7% 3 7% 5% 5% 5% 4 6% 7% 37%	2660
	21st to end	Day	14% 7% 2 6% 6% 4 5% 5% 6% 8% 38%	2660
July	1st to 10th	Day	10% 5% 2 6% 4 5% 5% 4 7% 9% 43%	4440
	11th to 20th	Day	9% 4 2 5% 4 4 5% 4 6% 9% 49%	4440
	21st to end	Day	9% 5% 2 4 4 3 4 4 6% 8% 50%	4814
August	1st to 10th	Day	14% 7% 3 7% 5% 5% 5% 4 6% 7% 37%	4423
	11th to 20th	Day	15% 5% 2 5% 3 3 3 3 4 7% 50%	4046
	21st to end	Day	14% 6% 2 6% 4 4 4 4 6% 9% 41%	4190
September	1st to 10th	Day	14% 6% 2 6% 4 4 5% 4 5% 9% 41%	2280
	11th to 20th	Day	14% 6% 2 6% 4 4 5% 5% 6% 8% 40%	2279
	21st to end	Day	21% 9% 2 6% 4 3 3 3 5% 6% 38%	2027
October	1st to 10th	Day	18% 11% 3 5% 3 4 4 3 5% 6% 36%	1900
	11th to 20th	Day	19% 18% 4 8% 5% 4 4 3 4 6% 27%	1900
	21st to end	Day	20% 17% 4 7% 5% 5% 5% 3 4 5% 27%	1913
November	1st to 10th	Day	12% 18% 5% 8% 5% 4 4 3 5% 6% 30%	1734
	11th to 20th	Day	13% 19% 9% 13% 7% 5% 4 2 4 5% 19%	1520
	21st to end	Day	13% 15% 6% 14% 8% 5% 4 3 4 5% 21%	1520
December	1st to 10th	Day	9% 17% 9% 17% 9% 6% 5% 3 3 5% 16%	1520
	11th to 20th	Day	10% 16% 8% 14% 11% 6% 6% 4 4 5% 17%	1914
	21st to end	Day	18% 17% 8% 19% 6% 5% 4 4 3 3 12%	2783
January	1st to 10th	Night	10% 17% 7% 16% 6% 5% 5% 3 4 4 22%	4428
	11th to 20th	Night	7% 14% 9% 15% 10% 9% 8% 6% 5% 5% 13%	4440
	21st to end	Night	8% 21% 8% 14% 6% 6% 6% 4 4 5% 19%	4823
February	1st to 10th	Night	6% 15% 7% 13% 7% 7% 6% 5% 4 5% 26%	2470
	11th to 20th	Night	8% 10% 5% 10% 9% 8% 7% 5% 6% 6% 27%	2403
	21st to end	Night	12% 16% 5% 10% 6% 5% 4 4 5% 6% 28%	1894
March	1st to 10th	Night	8% 9% 3 8% 5% 4 5% 4 6% 8% 40%	3722
	11th to 20th	Night	9% 12% 6% 15% 5% 4 4 3 4 6% 31%	3521
	21st to end	Night	19% 15% 5% 12% 5% 3 4 2 3 4 27%	3597
April	1st to 10th	Night	19% 14% 4 9% 5% 4 4 3 4 7% 28%	1900
	11th to 20th	Night	21% 12% 4 6% 4 4 4 4 5% 5% 33%	1875
	21st to end	Night	18% 13% 3 7% 4 4 4 3 5% 5% 34%	1725
May	1st to 10th	Night	17% 8% 3 7% 4 4 4 4 5% 7% 36%	2523
	11th to 20th	Night	13% 8% 2 5% 5% 4 4 3 5% 6% 45%	2506
	21st to end	Night	13% 8% 2 9% 5% 4 5% 5% 6% 7% 35%	2750
June	1st to 10th	Night	13% 5% 3 6% 4 4 5% 4 6% 8% 42%	1520
	11th to 20th	Night	12% 6% 2 7% 5% 5% 5% 4 7% 8% 39%	1520
	21st to end	Night	13% 6% 2 8% 4 5% 4 4 7% 7% 41%	1520
July	1st to 10th	Night	10% 5% 2 5% 3 5% 4 5% 6% 7% 49%	2530
	11th to 20th	Night	7% 4 2 4 4 3 3 3 6% 8% 54%	2530
	21st to end	Night	9% 7% 2 4 3 3 3 3 4 7% 54%	2750
August	1st to 10th	Night	14% 6% 2 6% 3 3 4 3 5% 9% 44%	2517
	11th to 20th	Night	14% 5% 2 4 3 3 4 3 5% 7% 51%	2790
	21st to end	Night	17% 6% 2 5% 2 3 4 3 5% 7% 45%	3466
September	1st to 10th	Night	11% 5% 2 5% 4 3 4 4 5% 7% 50%	1900
	11th to 20th	Night	10% 5% 1 5% 4 4 5% 5% 6% 8% 48%	1900
	21st to end	Night	18% 7% 2 7% 4 4 4 3 5% 7% 40%	2133
October	1st to 10th	Night	18% 8% 2 6% 4 3 3 3 4 6% 42%	2280
	11th to 20th	Night	18% 13% 5% 7% 4 4 4 3 4 6% 32%	2280
	21st to end	Night	21% 15% 3 7% 6% 5% 4 4 5% 5% 26%	2684
November	1st to 10th	Night	14% 15% 4 9% 6% 3 4 3 5% 6% 30%	2561
	11th to 20th	Night	12% 16% 7% 13% 7% 5% 4 3 5% 5% 23%	2667
	21st to end	Night	13% 14% 6% 13% 8% 5% 4 4 4 6% 23%	2660
December	1st to 10th	Night	10% 17% 7% 15% 7% 6% 5% 3 4 6% 19%	2660
	11th to 20th	Night	11% 16% 6% 13% 8% 6% 5% 3 5% 6% 20%	3283
	21st to end	Night	21% 20% 6% 13% 6% 4 4 3 3 4 17%	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	71% 5% 7% 14% 3	2528
	11th to 20th	Day	73% 7% 8% 9% 3	2530
	21st to end	Day	70% 6% 11% 10% 3	2829
February	1st to 10th	Day	58% 6% 11% 15% 10%	1710
	11th to 20th	Day	57% 8% 9% 19% 7%	1673
	21st to end	Day	59% 8% 9% 15% 9% 1	1560
March	1st to 10th	Day	47% 8% 16% 19% 10%	3120
	11th to 20th	Day	51% 7% 15% 18% 9%	3468
	21st to end	Day	61% 7% 10% 18% 5%	4033
April	1st to 10th	Day	57% 6% 10% 16% 10% 1	2280
	11th to 20th	Day	57% 4 10% 19% 9% 2	2254
	21st to end	Day	54% 7% 10% 19% 10% 1	2451
May	1st to 10th	Day	45% 7% 11% 22% 14% 1	4440
	11th to 20th	Day	41% 9% 14% 26% 9% 1	4403
	21st to end	Day	48% 9% 11% 17% 15% 1	4837
June	1st to 10th	Day	38% 8% 15% 25% 12% 1	2660
	11th to 20th	Day	43% 8% 13% 20% 14% 1	2660
	21st to end	Day	41% 10% 15% 25% 8% 1	2660
July	1st to 10th	Day	37% 6% 20% 25% 12% 1	4371
	11th to 20th	Day	30% 7% 17% 33% 13% 1	4365
	21st to end	Day	31% 5% 15% 33% 16% 1	4662
August	1st to 10th	Day	46% 5% 16% 23% 10% 1	4408
	11th to 20th	Day	36% 4 19% 31% 10%	4085
	21st to end	Day	41% 5% 18% 25% 10% 1	4189
September	1st to 10th	Day	39% 7% 16% 27% 10%	2280
	11th to 20th	Day	40% 9% 19% 25% 7%	2279
	21st to end	Day	46% 8% 13% 24% 9%	2027
October	1st to 10th	Day	37% 4 15% 29% 13% 1	3160
	11th to 20th	Day	54% 3 9% 23% 11% 1	3140
	21st to end	Day	54% 5% 16% 21% 5%	3125
November	1st to 10th	Day	55% 6% 12% 19% 7% 1	1734
	11th to 20th	Day	70% 5% 10% 11% 5%	1520
	21st to end	Day	64% 7% 13% 12% 3 1	1520
December	1st to 10th	Day	71% 6% 10% 11% 2	1520
	11th to 20th	Day	68% 9% 11% 9% 3	1915
	21st to end	Day	77% 6% 6% 10% 1	2783
January	1st to 10th	Night	65% 7% 10% 14% 2	4428
	11th to 20th	Night	68% 11% 12% 7% 1	4440
	21st to end	Night	68% 7% 8% 14% 2	4823
February	1st to 10th	Night	58% 7% 9% 17% 8% 1	2470
	11th to 20th	Night	54% 8% 12% 17% 7% 1	2404
	21st to end	Night	56% 6% 12% 18% 7% 1	1894
March	1st to 10th	Night	39% 8% 16% 22% 13% 1	3733
	11th to 20th	Night	52% 7% 13% 21% 6% 1	3522
	21st to end	Night	62% 6% 8% 15% 9% 1	3597
April	1st to 10th	Night	57% 6% 8% 16% 12% 1	1900
	11th to 20th	Night	52% 6% 10% 19% 10% 2	1875
	21st to end	Night	51% 6% 9% 22% 12% 1	1725
May	1st to 10th	Night	45% 8% 14% 19% 13% 1	2530
	11th to 20th	Night	38% 7% 12% 25% 15% 3	2507
	21st to end	Night	44% 11% 15% 18% 12% 1	2751
June	1st to 10th	Night	37% 8% 17% 26% 11% 2	1520
	11th to 20th	Night	40% 9% 12% 20% 17% 2	1520
	21st to end	Night	39% 9% 14% 25% 12% 1	1520
July	1st to 10th	Night	33% 7% 20% 26% 11% 3	2490
	11th to 20th	Night	26% 7% 16% 36% 13% 1	2482
	21st to end	Night	30% 5% 12% 29% 22% 2	2662
August	1st to 10th	Night	39% 4 15% 27% 13% 2	2508
	11th to 20th	Night	34% 5% 17% 32% 11% 1	2817
	21st to end	Night	40% 6% 17% 26% 11% 1	3466
September	1st to 10th	Night	32% 7% 15% 32% 13% 1	1900
	11th to 20th	Night	33% 8% 17% 33% 8%	1900
	21st to end	Night	45% 5% 16% 25% 9% 1	2133
October	1st to 10th	Night	32% 4 9% 33% 21% 2	3800
	11th to 20th	Night	48% 4 11% 22% 13%	3779
	21st to end	Night	57% 5% 11% 21% 7%	4422
November	1st to 10th	Night	54% 6% 13% 19% 8%	2561
	11th to 20th	Night	63% 7% 12% 12% 7%	2667
	21st to end	Night	61% 7% 15% 12% 4 1	2660
December	1st to 10th	Night	66% 8% 11% 12% 2	2660
	11th to 20th	Night	64% 9% 12% 13% 2	3281
	21st to end	Night	73% 5% 8% 11% 3	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	19% 23% 37% 16% 5% 1	270
	11th to 20th	Day	24% 20% 33% 21% 2	270
	21st to end	Day	20% 15% 44% 20% 2	297
February	1st to 10th	Day	18% 26% 43% 10% 3	270
	11th to 20th	Day	17% 36% 32% 9% 6%	270
	21st to end	Day	24% 25% 42% 8%	225
March	1st to 10th	Day	18% 21% 41% 17% 3	270
	11th to 20th	Day	22% 22% 37% 13% 5%	270
	21st to end	Day	25% 21% 34% 14% 5% 2	426
April	1st to 10th	Day	25% 21% 34% 14% 5%	460
	11th to 20th	Day	30% 19% 29% 17% 5%	452
	21st to end	Day	28% 19% 28% 18% 7% 1	550
May	1st to 10th	Day	25% 21% 31% 17% 5% 1	653
	11th to 20th	Day	22% 18% 33% 20% 5% 2	675
	21st to end	Day	22% 17% 33% 19% 7% 2	734
June	1st to 10th	Day	17% 20% 33% 20% 8% 1	680
	11th to 20th	Day	19% 16% 38% 19% 5% 2	680
	21st to end	Day	17% 16% 35% 20% 10% 2	680
July	1st to 10th	Day	10% 10% 36% 26% 14% 4	671
	11th to 20th	Day	12% 12% 34% 26% 11% 4	668
	21st to end	Day	10% 9% 39% 24% 13% 5%	739
August	1st to 10th	Day	14% 12% 32% 27% 12% 2	676
	11th to 20th	Day	17% 7% 30% 29% 14% 3	665
	21st to end	Day	20% 11% 30% 23% 13% 2	549
September	1st to 10th	Day	18% 15% 29% 24% 12% 2	490
	11th to 20th	Day	16% 14% 33% 27% 8% 2	490
	21st to end	Day	26% 15% 29% 19% 11% 1	427
October	1st to 10th	Day	25% 19% 27% 20% 7%	300
	11th to 20th	Day	29% 29% 32% 8% 3	300
	21st to end	Day	31% 24% 34% 9% 1	330
November	1st to 10th	Day	21% 26% 39% 10% 3	300
	11th to 20th	Day	26% 28% 36% 7% 3	270
	21st to end	Day	27% 23% 36% 11% 2	270
December	1st to 10th	Day	19% 21% 43% 13% 4	270
	11th to 20th	Day	26% 24% 34% 15% 1	270
	21st to end	Day	27% 25% 36% 9% 2	297
January	1st to 10th	Night	15% 21% 39% 19% 5%	950
	11th to 20th	Night	18% 18% 42% 16% 5%	950
	21st to end	Night	18% 18% 40% 20% 3	1045
February	1st to 10th	Night	16% 21% 37% 21% 5% 1	950
	11th to 20th	Night	14% 22% 37% 18% 8% 1	929
	21st to end	Night	19% 19% 36% 22% 4	638
March	1st to 10th	Night	17% 18% 36% 23% 5% 1	760
	11th to 20th	Night	19% 21% 33% 19% 7% 1	599
	21st to end	Night	21% 15% 29% 23% 10% 2	627
April	1st to 10th	Night	25% 16% 31% 23% 5% 1	570
	11th to 20th	Night	28% 12% 29% 24% 8%	563
	21st to end	Night	27% 10% 26% 27% 8% 1	570
May	1st to 10th	Night	22% 13% 33% 26% 5% 1	570
	11th to 20th	Night	19% 10% 32% 28% 8% 2	561
	21st to end	Night	17% 10% 33% 30% 10% 1	617
June	1st to 10th	Night	16% 8% 31% 34% 10% 1	570
	11th to 20th	Night	15% 8% 32% 35% 9%	570
	21st to end	Night	17% 7% 30% 31% 13% 1	570
July	1st to 10th	Night	8% 6% 26% 40% 19% 1	555
	11th to 20th	Night	11% 7% 34% 32% 17% 1	552
	21st to end	Night	11% 4 28% 38% 17% 2	624
August	1st to 10th	Night	12% 6% 24% 41% 17% 1	567
	11th to 20th	Night	16% 5% 23% 35% 19% 3	564
	21st to end	Night	16% 7% 28% 29% 18% 2	627
September	1st to 10th	Night	13% 8% 31% 31% 16% 2	570
	11th to 20th	Night	14% 9% 32% 31% 13% 1	570
	21st to end	Night	21% 13% 30% 25% 10% 1	741
October	1st to 10th	Night	25% 13% 28% 24% 10% 1	760
	11th to 20th	Night	28% 18% 31% 16% 6%	760
	21st to end	Night	30% 13% 31% 22% 5%	836
November	1st to 10th	Night	24% 15% 36% 20% 5%	805
	11th to 20th	Night	22% 22% 35% 16% 5%	953
	21st to end	Night	22% 23% 34% 17% 3	950
December	1st to 10th	Night	20% 20% 37% 19% 4 1	950
	11th to 20th	Night	20% 22% 33% 20% 5% 1	950
	21st to end	Night	29% 19% 34% 14% 3	1045

Page generated at 2024-11-08 05:44:46. Version ac07

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