Herridge Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Herridge Lake clear sky chart from 2005-11-06 to 2024-11-05.

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	17% 12% 4 9% 5% 4 4 3 5% 7% 30%	101721
	Night	16% 13% 5% 10% 6% 5% 4 3 5% 6% 28%	97362
Transparency	Day	53% 7% 12% 20% 8% 1	105256
	Night	55% 7% 11% 18% 8% 1	101916
Seeing	Day	23% 16% 31% 20% 8% 2	15177
	Night	24% 13% 31% 24% 8% 1	24169

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% 22% 8% 13% 6% 6% 5% 3 5% 6% 12%	2208
	11th to 20th	Day	11% 16% 9% 18% 8% 5% 4 3 4 6% 18%	2219
	21st to end	Day	16% 20% 9% 13% 6% 5% 5% 4 5% 5% 13%	3102
February	1st to 10th	Day	8% 18% 5% 13% 9% 7% 6% 3 5% 6% 19%	1710
	11th to 20th	Day	10% 20% 6% 11% 7% 5% 4 3 5% 5% 24%	1663
	21st to end	Day	15% 17% 5% 12% 7% 5% 4 4 5% 5% 22%	1420
March	1st to 10th	Day	19% 16% 5% 9% 5% 4 4 3 5% 6% 25%	3388
	11th to 20th	Day	11% 17% 5% 16% 7% 4 4 3 4 5% 25%	3480
	21st to end	Day	11% 15% 5% 11% 6% 5% 4 3 4 5% 31%	3815
April	1st to 10th	Day	19% 13% 5% 8% 4 4 4 3 5% 7% 26%	2253
	11th to 20th	Day	23% 10% 3 7% 4 4 4 3 5% 6% 32%	2416
	21st to end	Day	21% 13% 3 7% 4 4 3 3 4 5% 33%	2470
May	1st to 10th	Day	19% 11% 3 7% 5% 4 4 3 5% 6% 33%	4261
	11th to 20th	Day	16% 9% 3 7% 5% 5% 5% 3 5% 7% 35%	4398
	21st to end	Day	19% 8% 3 5% 4 4 4 3 5% 7% 39%	4869
June	1st to 10th	Day	19% 8% 3 7% 5% 4 4 4 6% 7% 31%	2850
	11th to 20th	Day	14% 6% 2 7% 5% 6% 5% 5% 6% 7% 36%	2850
	21st to end	Day	19% 9% 3 7% 6% 5% 5% 4 5% 8% 30%	2850
July	1st to 10th	Day	17% 8% 3 7% 5% 4 5% 5% 7% 8% 31%	4760
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 7% 9% 38%	4760
	21st to end	Day	13% 6% 2 6% 4 4 5% 4 6% 9% 43%	4825
August	1st to 10th	Day	12% 6% 2 8% 5% 5% 6% 5% 8% 10% 34%	4104
	11th to 20th	Day	20% 7% 2 6% 4 4 5% 4 6% 9% 35%	4044
	21st to end	Day	13% 6% 3 7% 5% 4 4 4 6% 8% 41%	4468
September	1st to 10th	Day	18% 8% 3 6% 5% 4 4 3 5% 8% 36%	2280
	11th to 20th	Day	18% 8% 2 6% 5% 4 4 3 4 7% 39%	2169
	21st to end	Day	22% 10% 3 7% 5% 4 3 3 5% 6% 32%	2054
October	1st to 10th	Day	21% 11% 3 7% 5% 4 3 3 5% 7% 31%	1900
	11th to 20th	Day	25% 16% 4 9% 5% 5% 4 3 4 4 22%	1900
	21st to end	Day	29% 18% 4 9% 5% 4 4 3 4 5% 16%	2026
November	1st to 10th	Day	21% 17% 6% 7% 5% 3 4 3 4 6% 25%	1518
	11th to 20th	Day	19% 18% 5% 14% 6% 5% 4 3 4 6% 17%	1520
	21st to end	Day	26% 20% 5% 13% 6% 5% 4 2 3 4 12%	1520
December	1st to 10th	Day	16% 23% 7% 13% 7% 5% 4 3 4 4 14%	1520
	11th to 20th	Day	17% 20% 7% 12% 6% 4 3 3 4 4 20%	1700
	21st to end	Day	17% 24% 8% 17% 7% 3 2 2 3 3 13%	2431
January	1st to 10th	Night	14% 18% 7% 15% 8% 6% 5% 3 4 5% 14%	4748
	11th to 20th	Night	11% 15% 6% 13% 8% 7% 6% 4 5% 4 18%	4748
	21st to end	Night	13% 22% 9% 12% 8% 6% 5% 3 5% 3 14%	4553
February	1st to 10th	Night	11% 16% 5% 12% 10% 6% 4 4 5% 5% 22%	2470
	11th to 20th	Night	12% 17% 7% 12% 8% 5% 3 4 5% 5% 23%	2403
	21st to end	Night	12% 19% 5% 12% 7% 5% 5% 3 5% 5% 22%	2032
March	1st to 10th	Night	15% 15% 4 9% 5% 5% 4 3 5% 5% 30%	3452
	11th to 20th	Night	12% 18% 6% 11% 6% 4 4 3 4 5% 26%	3479
	21st to end	Night	14% 10% 5% 11% 5% 5% 4 3 4 5% 33%	3817
April	1st to 10th	Night	20% 15% 4 9% 5% 3 4 3 4 4 29%	1926
	11th to 20th	Night	21% 11% 3 7% 4 4 4 4 4 6% 32%	1730
	21st to end	Night	20% 10% 3 7% 5% 4 4 3 6% 7% 32%	1710
May	1st to 10th	Night	17% 10% 3 8% 5% 5% 4 4 4 5% 34%	2678
	11th to 20th	Night	15% 9% 3 6% 4 4 4 3 6% 8% 37%	2495
	21st to end	Night	15% 8% 3 7% 4 4 4 3 5% 9% 37%	2690
June	1st to 10th	Night	16% 8% 3 7% 5% 5% 4 3 6% 6% 36%	1330
	11th to 20th	Night	17% 6% 2 5% 4 3 3 3 6% 9% 41%	1330
	21st to end	Night	16% 6% 3 7% 5% 4 4 5% 7% 7% 36%	1330
July	1st to 10th	Night	15% 7% 2 6% 4 4 5% 5% 5% 7% 41%	2210
	11th to 20th	Night	13% 8% 3 7% 5% 4 4 4 6% 8% 40%	2210
	21st to end	Night	12% 6% 2 6% 4 4 4 3 6% 9% 44%	2725
August	1st to 10th	Night	12% 6% 2 6% 4 5% 5% 4 7% 8% 41%	2825
	11th to 20th	Night	15% 7% 2 7% 4 4 4 3 5% 7% 41%	2785
	21st to end	Night	16% 6% 2 5% 4 3 4 3 4 7% 46%	3156
September	1st to 10th	Night	17% 6% 2 5% 2 4 4 3 6% 7% 44%	1900
	11th to 20th	Night	17% 7% 2 4 3 3 3 3 4 6% 47%	2008
	21st to end	Night	20% 9% 3 6% 4 3 3 3 5% 6% 39%	2125
October	1st to 10th	Night	19% 11% 3 8% 5% 4 4 3 4 5% 35%	2280
	11th to 20th	Night	27% 14% 3 6% 4 4 5% 3 5% 5% 24%	2280
	21st to end	Night	24% 17% 5% 9% 5% 3 3 3 3 4 24%	2570
November	1st to 10th	Night	20% 14% 4 8% 5% 4 3 4 4 6% 28%	2659
	11th to 20th	Night	19% 16% 5% 12% 7% 4 5% 4 5% 5% 19%	2660
	21st to end	Night	22% 20% 6% 11% 6% 4 4 3 4 4 16%	2660
December	1st to 10th	Night	19% 22% 7% 12% 7% 5% 4 3 4 5% 15%	2660
	11th to 20th	Night	17% 20% 6% 11% 7% 5% 4 3 5% 5% 16%	3492
	21st to end	Night	20% 21% 9% 15% 7% 4 3 2 3 3 14%	5236

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% 7% 12% 8% 2	2209
	11th to 20th	Day	69% 4 9% 12% 5% 1	2219
	21st to end	Day	74% 5% 8% 9% 4	3102
February	1st to 10th	Day	66% 5% 9% 12% 7% 1	1710
	11th to 20th	Day	62% 6% 9% 13% 9% 1	1672
	21st to end	Day	64% 5% 8% 14% 9% 1	1420
March	1st to 10th	Day	58% 8% 9% 17% 8% 1	3391
	11th to 20th	Day	60% 7% 10% 14% 8% 1	3480
	21st to end	Day	55% 6% 9% 17% 11% 2	3815
April	1st to 10th	Day	58% 4 11% 18% 8% 1	2253
	11th to 20th	Day	54% 5% 8% 22% 10% 1	2416
	21st to end	Day	54% 6% 7% 17% 14% 2	2470
May	1st to 10th	Day	48% 7% 11% 22% 10% 1	4273
	11th to 20th	Day	45% 8% 13% 25% 8% 1	4402
	21st to end	Day	44% 7% 12% 18% 17% 1	4869
June	1st to 10th	Day	51% 7% 12% 19% 10% 1	2850
	11th to 20th	Day	43% 9% 12% 23% 12% 1	2850
	21st to end	Day	51% 9% 11% 19% 9% 1	2850
July	1st to 10th	Day	47% 9% 15% 24% 6%	4686
	11th to 20th	Day	39% 8% 17% 29% 6%	4679
	21st to end	Day	38% 6% 16% 30% 9%	4671
August	1st to 10th	Day	42% 9% 15% 28% 6%	4091
	11th to 20th	Day	45% 8% 15% 24% 8% 1	4083
	21st to end	Day	40% 6% 14% 30% 8% 1	4468
September	1st to 10th	Day	47% 7% 14% 23% 9%	2280
	11th to 20th	Day	44% 8% 15% 25% 7%	2169
	21st to end	Day	52% 6% 15% 20% 7%	2054
October	1st to 10th	Day	50% 6% 11% 26% 6%	3160
	11th to 20th	Day	56% 6% 11% 19% 8%	3140
	21st to end	Day	68% 5% 15% 9% 4	3315
November	1st to 10th	Day	61% 6% 13% 14% 6%	1518
	11th to 20th	Day	68% 6% 9% 11% 4 1	1520
	21st to end	Day	77% 5% 7% 7% 3	1520
December	1st to 10th	Day	73% 5% 9% 10% 3	1520
	11th to 20th	Day	66% 6% 9% 15% 4	1700
	21st to end	Day	77% 5% 5% 11% 2	2431
January	1st to 10th	Night	69% 9% 12% 8% 2	4748
	11th to 20th	Night	66% 8% 10% 12% 4	4748
	21st to end	Night	74% 6% 6% 9% 5%	4553
February	1st to 10th	Night	64% 6% 9% 14% 7% 1	2470
	11th to 20th	Night	64% 5% 10% 14% 6% 1	2405
	21st to end	Night	62% 6% 8% 14% 8% 1	2032
March	1st to 10th	Night	54% 7% 10% 15% 11% 2	3462
	11th to 20th	Night	59% 7% 11% 15% 7% 1	3480
	21st to end	Night	51% 8% 9% 17% 13% 3	3817
April	1st to 10th	Night	58% 5% 9% 16% 11% 2	1926
	11th to 20th	Night	52% 5% 7% 19% 14% 2	1730
	21st to end	Night	50% 6% 12% 14% 16% 3	1710
May	1st to 10th	Night	48% 9% 9% 19% 13% 1	2685
	11th to 20th	Night	42% 9% 12% 24% 12% 2	2496
	21st to end	Night	41% 9% 12% 21% 14% 3	2691
June	1st to 10th	Night	47% 7% 11% 22% 10% 2	1330
	11th to 20th	Night	40% 6% 12% 24% 16% 2	1330
	21st to end	Night	45% 8% 13% 20% 13% 1	1330
July	1st to 10th	Night	41% 8% 13% 27% 11% 1	2175
	11th to 20th	Night	40% 7% 17% 26% 8%	2168
	21st to end	Night	36% 7% 13% 28% 15%	2639
August	1st to 10th	Night	39% 8% 16% 29% 9%	2814
	11th to 20th	Night	41% 7% 17% 28% 6%	2812
	21st to end	Night	38% 7% 16% 27% 11% 1	3156
September	1st to 10th	Night	38% 8% 17% 26% 10% 2	1900
	11th to 20th	Night	38% 7% 15% 30% 10%	2008
	21st to end	Night	45% 6% 16% 25% 8%	2125
October	1st to 10th	Night	49% 7% 11% 24% 9%	3800
	11th to 20th	Night	53% 6% 13% 23% 5%	3779
	21st to end	Night	58% 7% 18% 13% 5%	4231
November	1st to 10th	Night	55% 8% 16% 16% 5%	2659
	11th to 20th	Night	65% 7% 11% 12% 5% 1	2660
	21st to end	Night	71% 6% 11% 9% 3	2660
December	1st to 10th	Night	74% 6% 8% 10% 3	2660
	11th to 20th	Night	69% 7% 9% 11% 4	3491
	21st to end	Night	77% 4 5% 11% 3	5236

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	28% 21% 33% 13% 4 1	180
	11th to 20th	Day	20% 15% 43% 15% 7%	184
	21st to end	Day	24% 14% 32% 22% 6% 1	297
February	1st to 10th	Day	26% 27% 35% 9% 3	270
	11th to 20th	Day	25% 24% 38% 13% 1	270
	21st to end	Day	31% 28% 32% 8%	225
March	1st to 10th	Day	21% 21% 36% 19% 3	427
	11th to 20th	Day	21% 20% 37% 18% 3 1	460
	21st to end	Day	25% 22% 33% 15% 4 1	506
April	1st to 10th	Day	25% 19% 30% 18% 7% 1	460
	11th to 20th	Day	36% 16% 24% 15% 8% 2	452
	21st to end	Day	31% 20% 30% 12% 5% 2	460
May	1st to 10th	Day	26% 13% 30% 21% 9% 2	463
	11th to 20th	Day	22% 15% 33% 19% 9% 2	487
	21st to end	Day	22% 14% 34% 21% 7% 1	548
June	1st to 10th	Day	20% 15% 35% 23% 6% 1	680
	11th to 20th	Day	17% 17% 31% 25% 8% 2	680
	21st to end	Day	22% 12% 30% 27% 8% 1	680
July	1st to 10th	Day	12% 15% 33% 29% 9% 1	671
	11th to 20th	Day	17% 10% 32% 25% 13% 3	668
	21st to end	Day	14% 11% 29% 30% 13% 4	574
August	1st to 10th	Day	17% 10% 29% 28% 13% 3	486
	11th to 20th	Day	18% 6% 25% 27% 16% 8%	479
	21st to end	Day	19% 12% 30% 23% 13% 4	539
September	1st to 10th	Day	24% 10% 29% 22% 11% 3	490
	11th to 20th	Day	18% 9% 28% 29% 10% 5%	490
	21st to end	Day	26% 13% 25% 21% 13% 3	490
October	1st to 10th	Day	29% 15% 25% 20% 10% 1	490
	11th to 20th	Day	28% 22% 34% 11% 4 1	490
	21st to end	Day	35% 17% 32% 15% 1	475
November	1st to 10th	Day	36% 21% 31% 11% 2	188
	11th to 20th	Day	26% 25% 31% 15% 2 1	180
	21st to end	Day	38% 18% 31% 11% 3 1	180
December	1st to 10th	Day	28% 19% 32% 18% 3	180
	11th to 20th	Day	31% 18% 33% 13% 4 1	180
	21st to end	Day	29% 22% 36% 10% 3 1	198
January	1st to 10th	Night	26% 14% 36% 18% 5%	950
	11th to 20th	Night	27% 15% 31% 21% 5%	950
	21st to end	Night	21% 12% 31% 23% 11% 1	844
February	1st to 10th	Night	19% 18% 37% 21% 4 1	760
	11th to 20th	Night	23% 14% 39% 20% 4	743
	21st to end	Night	22% 20% 34% 19% 4	628
March	1st to 10th	Night	20% 21% 34% 20% 4 1	760
	11th to 20th	Night	24% 19% 33% 19% 6%	760
	21st to end	Night	21% 15% 36% 22% 5% 1	836
April	1st to 10th	Night	28% 15% 28% 23% 5%	760
	11th to 20th	Night	28% 17% 27% 20% 8%	606
	21st to end	Night	25% 14% 31% 22% 8% 1	570
May	1st to 10th	Night	22% 9% 30% 30% 8% 1	480
	11th to 20th	Night	20% 12% 31% 28% 9% 1	374
	21st to end	Night	19% 10% 35% 31% 5%	411
June	1st to 10th	Night	16% 11% 34% 31% 7% 1	380
	11th to 20th	Night	18% 11% 28% 31% 12%	380
	21st to end	Night	18% 8% 26% 32% 14% 1	380
July	1st to 10th	Night	12% 6% 35% 36% 11% 1	370
	11th to 20th	Night	13% 8% 27% 37% 15%	368
	21st to end	Night	11% 7% 28% 38% 15% 1	445
August	1st to 10th	Night	14% 6% 27% 35% 16% 2	567
	11th to 20th	Night	15% 6% 24% 34% 18% 3	564
	21st to end	Night	21% 8% 26% 29% 15% 2	646
September	1st to 10th	Night	21% 6% 28% 27% 17% 1	760
	11th to 20th	Night	20% 9% 25% 26% 17% 2	760
	21st to end	Night	24% 7% 24% 29% 13% 2	760
October	1st to 10th	Night	24% 13% 28% 26% 8% 1	760
	11th to 20th	Night	35% 12% 27% 18% 7% 1	760
	21st to end	Night	34% 14% 28% 21% 3 1	836
November	1st to 10th	Night	28% 13% 34% 20% 5%	760
	11th to 20th	Night	27% 17% 32% 18% 5%	760
	21st to end	Night	34% 14% 30% 17% 4	760
December	1st to 10th	Night	32% 17% 30% 15% 5% 1	760
	11th to 20th	Night	28% 15% 35% 17% 5% 1	916
	21st to end	Night	31% 16% 28% 20% 5%	1045

Page generated at 2024-11-03 02:11:10. Version ac07

Copyright © 2024 Attilla Danko.