North Ram
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the North Ram clear sky chart from 2005-11-06 to 2026-09-29.

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	8% 9% 3 9% 5% 5% 5% 5% 7% 8% 36%	155316
	Night	5% 9% 4 10% 6% 5% 5% 4 6% 8% 37%	144818
Transparency	Day	42% 8% 15% 22% 12% 2	155019
	Night	40% 7% 16% 23% 12% 2	144698
Seeing	Day	21% 16% 28% 22% 10% 2	18328
	Night	14% 14% 32% 27% 11% 1	26601

By Month

Percentage Cloud Cover NW (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	5% 3 11% 7% 7% 6% 5% 8% 11% 38%	4125
	11th to 20th	Day	1 6% 2 10% 5% 7% 5% 5% 6% 9% 44%	4317
	21st to end	Day	1 7% 4 12% 6% 5% 6% 6% 7% 11% 37%	5186
February	1st to 10th	Day	2 9% 6% 10% 9% 8% 6% 5% 8% 8% 30%	1680
	11th to 20th	Day	1 11% 5% 14% 6% 6% 6% 5% 7% 8% 31%	1739
	21st to end	Day	2 8% 4 15% 8% 5% 8% 5% 6% 7% 32%	1730
March	1st to 10th	Day	1 6% 4 10% 7% 5% 5% 5% 7% 11% 39%	4618
	11th to 20th	Day	3 9% 4 9% 5% 5% 6% 5% 8% 10% 39%	4880
	21st to end	Day	4 15% 8% 18% 5% 4 5% 4 7% 7% 24%	5919
April	1st to 10th	Day	4 18% 5% 11% 7% 7% 6% 4 7% 7% 24%	2520
	11th to 20th	Day	7% 17% 6% 12% 6% 5% 5% 4 6% 8% 24%	2698
	21st to end	Day	9% 16% 6% 12% 6% 6% 5% 3 5% 6% 26%	2772
May	1st to 10th	Day	9% 13% 3 8% 6% 5% 5% 4 6% 8% 31%	8195
	11th to 20th	Day	11% 13% 4 9% 6% 6% 6% 5% 7% 8% 24%	8752
	21st to end	Day	13% 11% 4 9% 6% 5% 6% 5% 6% 8% 27%	9649
June	1st to 10th	Day	19% 10% 3 8% 6% 5% 6% 4 6% 7% 26%	3150
	11th to 20th	Day	22% 10% 4 8% 5% 6% 6% 4 6% 8% 21%	3329
	21st to end	Day	13% 8% 3 7% 6% 6% 6% 5% 7% 8% 31%	3360
July	1st to 10th	Day	7% 5% 2 6% 4 4 5% 4 6% 9% 48%	9302
	11th to 20th	Day	10% 5% 2 6% 4 5% 5% 5% 7% 8% 43%	8820
	21st to end	Day	9% 5% 2 5% 4 4 5% 5% 7% 8% 46%	9216
August	1st to 10th	Day	11% 6% 2 5% 4 4 5% 4 7% 9% 42%	6441
	11th to 20th	Day	13% 6% 2 6% 5% 5% 6% 6% 8% 10% 34%	6241
	21st to end	Day	10% 5% 2 6% 4 4 4 4 6% 7% 48%	6570
September	1st to 10th	Day	14% 9% 2 6% 5% 5% 4 4 6% 7% 39%	2536
	11th to 20th	Day	12% 10% 2 6% 4 4 4 3 6% 7% 41%	2377
	21st to end	Day	9% 9% 3 8% 5% 4 5% 3 6% 8% 39%	2289
October	1st to 10th	Day	6% 9% 3 8% 4 4 5% 5% 5% 9% 42%	3436
	11th to 20th	Day	6% 9% 3 8% 5% 6% 5% 4 6% 9% 39%	2932
	21st to end	Day	4 9% 4 8% 5% 5% 6% 5% 7% 8% 41%	3200
November	1st to 10th	Day	4 11% 6% 12% 6% 5% 5% 5% 7% 7% 32%	1750
	11th to 20th	Day	3 8% 4 11% 5% 5% 4 6% 7% 9% 37%	1470
	21st to end	Day	2 10% 3 10% 6% 7% 5% 5% 8% 11% 34%	1470
December	1st to 10th	Day	2 9% 4 14% 8% 6% 7% 5% 7% 7% 30%	2360
	11th to 20th	Day	1 7% 3 11% 7% 7% 6% 5% 6% 9% 39%	2712
	21st to end	Day	1 9% 4 10% 7% 6% 6% 4 5% 7% 42%	3575
January	1st to 10th	Night	1 6% 4 13% 8% 8% 7% 5% 8% 9% 31%	8768
	11th to 20th	Night	1 5% 3 10% 8% 7% 6% 5% 7% 8% 40%	8626
	21st to end	Night	1 7% 4 12% 8% 7% 7% 5% 7% 9% 34%	8994
February	1st to 10th	Night	2 9% 4 10% 9% 8% 7% 4 6% 9% 31%	2940
	11th to 20th	Night	2 10% 5% 12% 7% 7% 6% 6% 7% 8% 32%	2766
	21st to end	Night	7% 5% 13% 8% 6% 6% 5% 7% 8% 35%	2076
March	1st to 10th	Night	1 7% 4 12% 6% 6% 6% 5% 6% 10% 37%	5496
	11th to 20th	Night	3 7% 5% 11% 6% 5% 5% 5% 8% 11% 36%	5338
	21st to end	Night	4 15% 7% 15% 5% 4 4 3 5% 7% 28%	5296
April	1st to 10th	Night	4 13% 5% 10% 7% 6% 5% 5% 6% 8% 31%	2100
	11th to 20th	Night	6% 15% 5% 12% 6% 5% 4 4 6% 7% 30%	1872
	21st to end	Night	6% 16% 5% 9% 5% 5% 5% 4 6% 6% 34%	1846
May	1st to 10th	Night	11% 14% 3 8% 4 4 4 3 5% 7% 36%	4724
	11th to 20th	Night	11% 13% 3 8% 6% 6% 6% 5% 8% 8% 26%	4106
	21st to end	Night	9% 8% 3 7% 5% 4 5% 4 7% 9% 40%	4522
June	1st to 10th	Night	19% 9% 3 6% 4 4 4 4 6% 7% 33%	1470
	11th to 20th	Night	18% 9% 3 8% 5% 5% 6% 4 7% 8% 28%	1286
	21st to end	Night	12% 7% 2 6% 5% 4 5% 4 6% 8% 41%	1260
July	1st to 10th	Night	8% 7% 3 7% 4 4 4 4 6% 9% 43%	3655
	11th to 20th	Night	8% 4 1 4 3 3 3 4 6% 8% 54%	4140
	21st to end	Night	9% 5% 2 5% 4 3 4 4 5% 6% 52%	4850
August	1st to 10th	Night	13% 8% 3 6% 3 3 4 3 4 8% 45%	3709
	11th to 20th	Night	12% 7% 2 5% 3 4 4 4 8% 10% 40%	3808
	21st to end	Night	11% 6% 2 5% 4 4 3 3 6% 9% 46%	4578
September	1st to 10th	Night	11% 7% 3 5% 4 3 4 4 5% 8% 46%	2082
	11th to 20th	Night	13% 10% 3 6% 3 3 3 3 5% 8% 44%	2242
	21st to end	Night	8% 9% 3 6% 3 3 5% 4 7% 8% 44%	2288
October	1st to 10th	Night	6% 8% 3 6% 5% 5% 5% 5% 7% 8% 42%	3758
	11th to 20th	Night	6% 8% 3 8% 5% 4 5% 4 7% 8% 42%	4216
	21st to end	Night	4 9% 4 9% 5% 4 4 4 6% 7% 45%	4600
November	1st to 10th	Night	3 13% 5% 11% 5% 5% 5% 4 6% 7% 36%	2743
	11th to 20th	Night	2 9% 4 9% 6% 7% 6% 5% 7% 10% 36%	3150
	21st to end	Night	2 9% 4 12% 7% 5% 6% 5% 6% 9% 34%	3150
December	1st to 10th	Night	2 7% 4 12% 8% 7% 7% 5% 7% 8% 32%	5040
	11th to 20th	Night	1 9% 4 12% 9% 8% 6% 5% 8% 8% 29%	5700
	21st to end	Night	1 9% 5% 13% 7% 5% 5% 4 6% 8% 37%	7623

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	36% 6% 15% 24% 15% 4	4125
	11th to 20th	Day	34% 6% 17% 22% 17% 4	4338
	21st to end	Day	35% 9% 19% 25% 12% 1	5187
February	1st to 10th	Day	45% 9% 13% 15% 14% 4	1680
	11th to 20th	Day	46% 10% 12% 19% 12% 2	1747
	21st to end	Day	47% 7% 14% 15% 14% 2	1730
March	1st to 10th	Day	33% 6% 21% 19% 19% 2	4618
	11th to 20th	Day	35% 8% 16% 20% 20% 1	4881
	21st to end	Day	55% 8% 12% 15% 8% 2	5919
April	1st to 10th	Day	56% 8% 16% 14% 6%	2520
	11th to 20th	Day	57% 7% 13% 16% 6% 1	2698
	21st to end	Day	58% 8% 12% 16% 6% 1	2772
May	1st to 10th	Day	47% 7% 13% 23% 9%	8195
	11th to 20th	Day	51% 8% 12% 20% 8% 1	8756
	21st to end	Day	50% 8% 18% 18% 6%	9650
June	1st to 10th	Day	55% 8% 12% 16% 8% 2	3150
	11th to 20th	Day	59% 9% 11% 12% 8% 1	3329
	21st to end	Day	48% 10% 15% 17% 9% 1	3360
July	1st to 10th	Day	30% 5% 13% 26% 20% 4	9224
	11th to 20th	Day	35% 8% 14% 23% 16% 6%	8739
	21st to end	Day	32% 7% 15% 26% 18% 2	9016
August	1st to 10th	Day	35% 8% 15% 30% 11% 1	6424
	11th to 20th	Day	40% 10% 18% 25% 7% 1	6283
	21st to end	Day	34% 7% 17% 33% 10% 1	6569
September	1st to 10th	Day	43% 8% 15% 22% 11% 2	2536
	11th to 20th	Day	40% 6% 15% 25% 12% 2	2377
	21st to end	Day	41% 7% 19% 19% 11% 3	2289
October	1st to 10th	Day	37% 7% 20% 28% 8% 1	3436
	11th to 20th	Day	39% 7% 18% 22% 13% 1	2932
	21st to end	Day	38% 7% 13% 33% 9% 1	3200
November	1st to 10th	Day	47% 9% 15% 17% 10% 2	1750
	11th to 20th	Day	38% 9% 19% 21% 12% 1	1470
	21st to end	Day	39% 9% 19% 20% 9% 4	1470
December	1st to 10th	Day	48% 9% 18% 16% 8% 1	2360
	11th to 20th	Day	39% 7% 19% 23% 10% 1	2714
	21st to end	Day	38% 5% 11% 23% 17% 5%	3575
January	1st to 10th	Night	44% 7% 14% 20% 14% 2	8769
	11th to 20th	Night	37% 7% 17% 17% 16% 7%	8667
	21st to end	Night	40% 9% 21% 20% 10% 1	8994
February	1st to 10th	Night	46% 9% 13% 16% 14% 3	2940
	11th to 20th	Night	44% 9% 17% 15% 13% 2	2768
	21st to end	Night	43% 6% 13% 22% 14% 2	2076
March	1st to 10th	Night	38% 6% 21% 18% 16% 3	5496
	11th to 20th	Night	37% 7% 16% 21% 18%	5338
	21st to end	Night	52% 6% 11% 17% 13% 1	5296
April	1st to 10th	Night	46% 8% 16% 18% 10% 1	2100
	11th to 20th	Night	51% 6% 15% 17% 10% 1	1872
	21st to end	Night	48% 10% 12% 22% 7% 1	1846
May	1st to 10th	Night	47% 5% 12% 26% 9% 1	4721
	11th to 20th	Night	48% 7% 12% 24% 9%	4106
	21st to end	Night	36% 7% 21% 28% 8%	4526
June	1st to 10th	Night	48% 8% 13% 20% 10% 1	1470
	11th to 20th	Night	52% 9% 15% 15% 8% 1	1286
	21st to end	Night	37% 9% 19% 25% 8% 2	1260
July	1st to 10th	Night	36% 6% 15% 26% 14% 4	3624
	11th to 20th	Night	26% 6% 19% 27% 16% 6%	4098
	21st to end	Night	31% 5% 18% 28% 16% 2	4745
August	1st to 10th	Night	37% 7% 14% 35% 6% 1	3701
	11th to 20th	Night	35% 8% 24% 27% 5%	3832
	21st to end	Night	35% 5% 19% 33% 7%	4578
September	1st to 10th	Night	35% 8% 17% 28% 9% 3	2082
	11th to 20th	Night	39% 6% 15% 26% 11% 2	2242
	21st to end	Night	35% 7% 19% 26% 12% 1	2288
October	1st to 10th	Night	34% 8% 16% 27% 13% 1	3758
	11th to 20th	Night	36% 7% 16% 30% 10% 1	4216
	21st to end	Night	36% 7% 15% 31% 11%	4600
November	1st to 10th	Night	44% 9% 13% 20% 11% 3	2743
	11th to 20th	Night	39% 10% 17% 20% 12% 2	3150
	21st to end	Night	42% 10% 14% 20% 10% 3	3150
December	1st to 10th	Night	46% 7% 19% 18% 9% 2	5040
	11th to 20th	Night	48% 10% 15% 16% 11% 1	5697
	21st to end	Night	42% 6% 12% 22% 14% 4	7623

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	11% 17% 27% 28% 12% 4	220
	11th to 20th	Day	16% 15% 35% 24% 8% 3	220
	21st to end	Day	16% 19% 39% 19% 5% 2	242
February	1st to 10th	Day	21% 15% 37% 18% 7% 2	220
	11th to 20th	Day	11% 20% 37% 23% 9%	281
	21st to end	Day	18% 23% 29% 21% 8% 2	446
March	1st to 10th	Day	19% 22% 33% 17% 7% 2	540
	11th to 20th	Day	19% 20% 34% 19% 6% 2	540
	21st to end	Day	23% 23% 28% 18% 7% 2	594
April	1st to 10th	Day	24% 21% 29% 19% 6% 1	540
	11th to 20th	Day	20% 22% 28% 20% 8% 2	532
	21st to end	Day	23% 19% 26% 20% 9% 2	540
May	1st to 10th	Day	26% 19% 26% 21% 8% 1	543
	11th to 20th	Day	20% 11% 30% 25% 12% 2	772
	21st to end	Day	27% 10% 24% 24% 12% 3	844
June	1st to 10th	Day	25% 16% 28% 22% 8% 2	780
	11th to 20th	Day	28% 14% 24% 21% 11% 2	959
	21st to end	Day	18% 13% 24% 25% 16% 3	990
July	1st to 10th	Day	17% 13% 26% 29% 13% 2	937
	11th to 20th	Day	19% 11% 27% 25% 16% 2	768
	21st to end	Day	16% 13% 28% 26% 14% 3	727
August	1st to 10th	Day	16% 15% 27% 27% 11% 4	567
	11th to 20th	Day	16% 17% 30% 24% 10% 3	557
	21st to end	Day	17% 15% 28% 25% 12% 3	627
September	1st to 10th	Day	23% 18% 26% 21% 9% 2	570
	11th to 20th	Day	21% 13% 27% 26% 9% 3	570
	21st to end	Day	28% 20% 27% 18% 7% 1	563
October	1st to 10th	Day	24% 16% 29% 18% 10% 4	505
	11th to 20th	Day	23% 15% 29% 21% 9% 2	330
	21st to end	Day	23% 18% 31% 20% 7% 1	363
November	1st to 10th	Day	24% 24% 29% 16% 5% 2	319
	11th to 20th	Day	25% 17% 33% 17% 7% 1	220
	21st to end	Day	18% 19% 31% 21% 8% 3	220
December	1st to 10th	Day	16% 21% 32% 18% 9% 4	220
	11th to 20th	Day	17% 21% 34% 20% 7%	220
	21st to end	Day	15% 12% 32% 29% 10% 2	242
January	1st to 10th	Night	13% 18% 38% 24% 6%	1050
	11th to 20th	Night	13% 18% 43% 20% 6% 1	1001
	21st to end	Night	14% 19% 41% 18% 7% 1	924
February	1st to 10th	Night	12% 17% 33% 26% 11% 1	840
	11th to 20th	Night	10% 14% 38% 30% 7%	824
	21st to end	Night	8% 14% 37% 25% 14% 1	692
March	1st to 10th	Night	9% 17% 36% 27% 10% 1	840
	11th to 20th	Night	11% 15% 37% 27% 9% 1	840
	21st to end	Night	13% 14% 32% 28% 11% 2	924
April	1st to 10th	Night	14% 16% 27% 30% 14%	840
	11th to 20th	Night	15% 16% 33% 26% 9%	624
	21st to end	Night	20% 16% 27% 27% 10% 1	586
May	1st to 10th	Night	22% 9% 24% 31% 13% 1	420
	11th to 20th	Night	16% 7% 24% 36% 15% 2	414
	21st to end	Night	24% 5% 19% 30% 21% 1	455
June	1st to 10th	Night	25% 10% 24% 25% 14% 2	420
	11th to 20th	Night	20% 10% 21% 30% 17% 1	420
	21st to end	Night	17% 9% 17% 32% 22% 3	420
July	1st to 10th	Night	16% 4 20% 38% 21% 1	410
	11th to 20th	Night	15% 8% 21% 36% 20%	408
	21st to end	Night	12% 6% 15% 41% 24% 3	460
August	1st to 10th	Night	19% 3 14% 33% 28% 4	418
	11th to 20th	Night	14% 4 18% 38% 24% 2	469
	21st to end	Night	15% 9% 18% 37% 19% 1	693
September	1st to 10th	Night	15% 9% 23% 35% 17% 2	822
	11th to 20th	Night	20% 7% 19% 33% 19% 2	840
	21st to end	Night	17% 14% 31% 26% 11% 1	832
October	1st to 10th	Night	17% 12% 27% 32% 11% 2	800
	11th to 20th	Night	15% 15% 33% 28% 7% 1	800
	21st to end	Night	16% 16% 37% 22% 7% 1	880
November	1st to 10th	Night	16% 19% 35% 23% 8%	880
	11th to 20th	Night	14% 23% 38% 20% 4 1	1050
	21st to end	Night	12% 21% 35% 23% 8% 1	1050
December	1st to 10th	Night	12% 19% 40% 21% 7% 1	1050
	11th to 20th	Night	9% 20% 38% 24% 8% 1	1050
	21st to end	Night	9% 17% 41% 24% 8% 1	1155

Page generated at 2026-09-26 02:18:41. Version ac07

Copyright © 2026 Attilla Danko.