Goudie Road
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goudie Road clear sky chart from 2005-11-06 to 2024-02-15.

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	12% 13% 5% 8% 7% 4 5% 5% 5% 6% 31%	78442
	Night	11% 14% 5% 9% 6% 4 5% 5% 5% 6% 31%	80577
Transparency	Day	53% 9% 13% 16% 8% 2	78162
	Night	53% 9% 13% 16% 8% 1	80437
Seeing	Day	18% 15% 26% 24% 14% 4	14285
	Night	17% 11% 23% 28% 17% 3	22987

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	11% 19% 9% 13% 13% 4 5% 4 4 5% 13%	2539
	11th to 20th	Day	9% 17% 6% 11% 8% 4 4 4 5% 8% 25%	2516
	21st to end	Day	10% 22% 9% 11% 8% 3 6% 5% 5% 5% 17%	2794
February	1st to 10th	Day	14% 19% 7% 11% 7% 3 5% 4 5% 4 21%	1534
	11th to 20th	Day	9% 18% 10% 14% 7% 3 5% 4 4 5% 20%	1612
	21st to end	Day	9% 19% 10% 13% 9% 5% 5% 3 5% 5% 17%	1480
March	1st to 10th	Day	11% 15% 7% 15% 7% 5% 6% 5% 6% 5% 18%	1800
	11th to 20th	Day	12% 19% 8% 9% 7% 3 4 5% 5% 6% 23%	1857
	21st to end	Day	11% 20% 7% 11% 7% 3 5% 5% 5% 6% 18%	2366
April	1st to 10th	Day	11% 19% 7% 11% 8% 5% 6% 5% 5% 5% 18%	2160
	11th to 20th	Day	12% 16% 7% 10% 8% 5% 5% 4 6% 4 24%	2167
	21st to end	Day	12% 16% 5% 9% 7% 4 5% 4 5% 7% 25%	2443
May	1st to 10th	Day	13% 15% 4 7% 6% 3 4 6% 5% 7% 31%	2520
	11th to 20th	Day	13% 12% 3 8% 7% 4 6% 5% 6% 7% 28%	2477
	21st to end	Day	19% 9% 4 8% 8% 4 6% 5% 6% 6% 26%	2785
June	1st to 10th	Day	22% 10% 4 8% 7% 5% 5% 4 4 6% 26%	2700
	11th to 20th	Day	23% 10% 4 8% 7% 4 5% 5% 5% 5% 23%	2854
	21st to end	Day	13% 7% 3 6% 7% 4 6% 5% 6% 6% 36%	2880
July	1st to 10th	Day	10% 6% 2 5% 5% 4 5% 5% 5% 7% 45%	2783
	11th to 20th	Day	7% 4 3 5% 5% 2 4 4 5% 6% 54%	2520
	21st to end	Day	5% 3 1 3 4 2 4 3 5% 6% 64%	2741
August	1st to 10th	Day	6% 4 2 4 5% 2 5% 5% 6% 7% 55%	2507
	11th to 20th	Day	7% 4 2 4 4 2 5% 5% 5% 6% 56%	2475
	21st to end	Day	11% 7% 3 6% 5% 3 5% 5% 6% 7% 42%	2408
September	1st to 10th	Day	11% 5% 2 4 4 3 4 4 6% 6% 50%	2160
	11th to 20th	Day	12% 8% 2 6% 6% 3 6% 4 5% 5% 43%	2124
	21st to end	Day	16% 9% 3 5% 5% 3 3 5% 5% 7% 38%	1980
October	1st to 10th	Day	13% 13% 3 7% 5% 3 4 4 4 6% 37%	1807
	11th to 20th	Day	15% 13% 4 8% 5% 4 6% 4 5% 5% 31%	1728
	21st to end	Day	20% 15% 5% 7% 5% 3 4 4 5% 6% 26%	1782
November	1st to 10th	Day	19% 17% 5% 10% 7% 4 5% 5% 5% 6% 18%	1605
	11th to 20th	Day	15% 17% 7% 10% 7% 3 4 6% 4 5% 21%	1520
	21st to end	Day	15% 16% 6% 10% 5% 3 5% 6% 6% 6% 23%	1358
December	1st to 10th	Day	10% 15% 5% 10% 9% 3 7% 6% 6% 7% 22%	1330
	11th to 20th	Day	10% 18% 7% 11% 8% 5% 6% 5% 6% 4 20%	1682
	21st to end	Day	10% 16% 7% 11% 7% 4 7% 6% 6% 7% 19%	2448
January	1st to 10th	Night	13% 21% 9% 15% 8% 4 5% 4 5% 4 12%	4429
	11th to 20th	Night	8% 16% 6% 11% 7% 3 4 4 8% 7% 24%	4382
	21st to end	Night	11% 21% 8% 11% 8% 4 6% 5% 5% 6% 16%	4862
February	1st to 10th	Night	13% 18% 7% 11% 7% 4 5% 4 5% 5% 21%	2642
	11th to 20th	Night	9% 19% 8% 11% 6% 4 4 4 4 5% 27%	2329
	21st to end	Night	8% 18% 8% 11% 8% 4 4 4 5% 5% 24%	1776
March	1st to 10th	Night	9% 16% 6% 10% 9% 5% 5% 4 4 7% 26%	2160
	11th to 20th	Night	10% 15% 5% 9% 6% 3 5% 5% 5% 7% 29%	2101
	21st to end	Night	9% 17% 5% 8% 7% 4 6% 5% 6% 6% 27%	1990
April	1st to 10th	Night	9% 14% 5% 7% 8% 4 6% 5% 6% 7% 30%	1800
	11th to 20th	Night	11% 13% 4 7% 8% 5% 6% 5% 5% 6% 30%	1743
	21st to end	Night	9% 14% 5% 7% 7% 4 5% 5% 4 7% 33%	1515
May	1st to 10th	Night	10% 12% 3 7% 7% 3 5% 4 6% 5% 37%	1440
	11th to 20th	Night	10% 10% 3 6% 5% 4 5% 6% 8% 7% 35%	1416
	21st to end	Night	14% 9% 3 6% 5% 3 5% 6% 6% 8% 35%	1485
June	1st to 10th	Night	18% 9% 4 6% 4 3 5% 5% 7% 6% 31%	1260
	11th to 20th	Night	18% 7% 3 7% 6% 4 4 5% 7% 7% 33%	1100
	21st to end	Night	8% 5% 3 5% 5% 5% 6% 5% 5% 8% 45%	1080
July	1st to 10th	Night	6% 6% 2 4 4 3 3 4 5% 7% 54%	1171
	11th to 20th	Night	6% 4 2 5% 5% 2 5% 5% 6% 7% 54%	1440
	21st to end	Night	4 2 1 2 3 2 2 3 4 7% 69%	1576
August	1st to 10th	Night	6% 3 1 3 3 2 5% 4 4 6% 62%	1432
	11th to 20th	Night	5% 2 1 2 4 2 4 3 4 8% 64%	1424
	21st to end	Night	8% 4 2 4 4 3 5% 5% 6% 8% 50%	1945
September	1st to 10th	Night	8% 6% 2 5% 6% 3 5% 4 4 5% 54%	1800
	11th to 20th	Night	12% 7% 3 5% 5% 3 4 4 5% 5% 48%	1836
	21st to end	Night	13% 8% 4 6% 4 3 5% 4 5% 8% 40%	1980
October	1st to 10th	Night	12% 9% 3 5% 5% 3 5% 6% 4 5% 41%	2150
	11th to 20th	Night	16% 11% 4 6% 6% 3 4 4 5% 5% 34%	2232
	21st to end	Night	16% 15% 5% 7% 5% 3 4 4 5% 5% 31%	2574
November	1st to 10th	Night	19% 17% 5% 8% 6% 3 5% 5% 4 6% 23%	2471
	11th to 20th	Night	15% 17% 6% 9% 7% 3 4 4 4 5% 25%	2660
	21st to end	Night	13% 17% 7% 10% 6% 4 4 5% 5% 6% 22%	2802
December	1st to 10th	Night	10% 14% 7% 11% 8% 4 5% 5% 5% 5% 25%	2850
	11th to 20th	Night	10% 21% 7% 11% 7% 4 5% 5% 5% 5% 19%	3510
	21st to end	Night	9% 17% 7% 12% 8% 5% 5% 6% 5% 5% 20%	5214

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	70% 12% 13% 4 2	2539
	11th to 20th	Day	57% 7% 15% 13% 3 5%	2540
	21st to end	Day	67% 14% 9% 8% 2	2794
February	1st to 10th	Day	65% 9% 11% 10% 4 1	1534
	11th to 20th	Day	65% 8% 11% 10% 5%	1621
	21st to end	Day	70% 8% 9% 10% 3	1480
March	1st to 10th	Day	66% 10% 11% 10% 4 1	1800
	11th to 20th	Day	62% 7% 12% 15% 5%	1857
	21st to end	Day	67% 8% 13% 9% 4	2366
April	1st to 10th	Day	66% 10% 10% 11% 3	2160
	11th to 20th	Day	62% 7% 11% 13% 6% 1	2167
	21st to end	Day	59% 8% 13% 16% 5%	2443
May	1st to 10th	Day	51% 9% 15% 16% 8% 1	2520
	11th to 20th	Day	54% 8% 14% 18% 5%	2480
	21st to end	Day	57% 9% 14% 16% 3 1	2786
June	1st to 10th	Day	60% 7% 10% 13% 7% 3	2700
	11th to 20th	Day	62% 8% 11% 14% 5%	2854
	21st to end	Day	46% 9% 14% 19% 10% 2	2880
July	1st to 10th	Day	38% 7% 12% 20% 17% 5%	2708
	11th to 20th	Day	31% 7% 13% 24% 20% 5%	2445
	21st to end	Day	22% 6% 12% 27% 28% 6%	2589
August	1st to 10th	Day	27% 8% 16% 24% 20% 5%	2490
	11th to 20th	Day	26% 7% 16% 29% 18% 4	2475
	21st to end	Day	38% 8% 15% 26% 13% 1	2408
September	1st to 10th	Day	34% 6% 17% 27% 14% 2	2160
	11th to 20th	Day	42% 8% 12% 22% 15% 2	2124
	21st to end	Day	45% 9% 18% 18% 9% 1	1980
October	1st to 10th	Day	48% 7% 15% 23% 7%	1807
	11th to 20th	Day	53% 8% 15% 20% 5%	1728
	21st to end	Day	58% 9% 14% 14% 5%	1782
November	1st to 10th	Day	67% 8% 12% 9% 4	1605
	11th to 20th	Day	65% 9% 12% 10% 3 1	1520
	21st to end	Day	59% 12% 15% 8% 5%	1358
December	1st to 10th	Day	60% 11% 12% 14% 4	1330
	11th to 20th	Day	64% 15% 10% 7% 4	1684
	21st to end	Day	61% 15% 12% 9% 3	2448
January	1st to 10th	Night	72% 12% 9% 5% 2	4429
	11th to 20th	Night	54% 8% 14% 13% 4 6%	4420
	21st to end	Night	68% 13% 9% 6% 3	4862
February	1st to 10th	Night	64% 7% 12% 11% 4 1	2642
	11th to 20th	Night	60% 7% 12% 14% 6% 1	2331
	21st to end	Night	60% 7% 13% 12% 7%	1776
March	1st to 10th	Night	58% 8% 15% 12% 7%	2160
	11th to 20th	Night	53% 9% 14% 16% 7%	2102
	21st to end	Night	56% 9% 16% 14% 5%	1990
April	1st to 10th	Night	49% 11% 20% 15% 6%	1800
	11th to 20th	Night	54% 9% 15% 14% 8% 1	1743
	21st to end	Night	49% 9% 14% 20% 8%	1515
May	1st to 10th	Night	46% 9% 17% 18% 11% 1	1440
	11th to 20th	Night	42% 10% 18% 21% 9%	1416
	21st to end	Night	46% 10% 16% 22% 5%	1485
June	1st to 10th	Night	49% 9% 13% 18% 10% 2	1260
	11th to 20th	Night	47% 11% 15% 20% 8%	1100
	21st to end	Night	36% 10% 17% 25% 10% 2	1080
July	1st to 10th	Night	29% 7% 14% 27% 18% 5%	1137
	11th to 20th	Night	27% 8% 14% 27% 20% 4	1392
	21st to end	Night	15% 4 14% 31% 30% 6%	1488
August	1st to 10th	Night	22% 6% 12% 29% 24% 6%	1424
	11th to 20th	Night	19% 7% 16% 32% 23% 4	1424
	21st to end	Night	29% 7% 16% 31% 15% 2	1945
September	1st to 10th	Night	31% 7% 14% 28% 17% 3	1800
	11th to 20th	Night	36% 7% 13% 22% 18% 4	1836
	21st to end	Night	41% 9% 16% 22% 11% 1	1980
October	1st to 10th	Night	43% 9% 15% 25% 7% 1	2150
	11th to 20th	Night	51% 7% 13% 21% 9%	2232
	21st to end	Night	54% 8% 15% 17% 6%	2574
November	1st to 10th	Night	62% 9% 12% 12% 5%	2471
	11th to 20th	Night	64% 8% 12% 10% 5% 1	2660
	21st to end	Night	63% 10% 13% 8% 5%	2802
December	1st to 10th	Night	60% 9% 13% 14% 3	2850
	11th to 20th	Night	67% 13% 11% 7% 2	3507
	21st to end	Night	64% 13% 11% 9% 3	5214

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% 19% 31% 16% 9% 6%	180
	11th to 20th	Day	15% 21% 28% 21% 12% 3	180
	21st to end	Day	17% 19% 32% 22% 7% 3	198
February	1st to 10th	Day	24% 21% 31% 16% 7% 1	194
	11th to 20th	Day	21% 22% 28% 22% 5% 2	348
	21st to end	Day	16% 16% 34% 21% 11% 2	346
March	1st to 10th	Day	22% 23% 28% 17% 9% 1	420
	11th to 20th	Day	20% 24% 23% 18% 12% 3	420
	21st to end	Day	24% 22% 24% 16% 12% 3	462
April	1st to 10th	Day	20% 23% 28% 19% 9% 1	420
	11th to 20th	Day	22% 20% 24% 18% 10% 5%	412
	21st to end	Day	18% 18% 30% 20% 10% 4	420
May	1st to 10th	Day	15% 18% 25% 27% 10% 4	423
	11th to 20th	Day	20% 11% 22% 23% 19% 5%	448
	21st to end	Day	20% 10% 21% 23% 20% 6%	547
June	1st to 10th	Day	22% 11% 27% 23% 15% 2	630
	11th to 20th	Day	25% 14% 23% 23% 13% 3	784
	21st to end	Day	14% 10% 23% 26% 20% 6%	810
July	1st to 10th	Day	13% 12% 21% 32% 18% 4	703
	11th to 20th	Day	8% 11% 33% 31% 15% 2	444
	21st to end	Day	5% 8% 26% 36% 19% 5%	487
August	1st to 10th	Day	7% 10% 24% 32% 20% 7%	447
	11th to 20th	Day	8% 8% 29% 29% 20% 7%	437
	21st to end	Day	13% 13% 26% 29% 14% 5%	495
September	1st to 10th	Day	16% 12% 27% 25% 14% 5%	450
	11th to 20th	Day	17% 11% 26% 26% 17% 3	450
	21st to end	Day	21% 15% 26% 22% 12% 4	450
October	1st to 10th	Day	19% 15% 26% 23% 14% 4	450
	11th to 20th	Day	21% 21% 23% 17% 15% 3	378
	21st to end	Day	27% 14% 28% 21% 8% 2	297
November	1st to 10th	Day	27% 20% 25% 18% 9% 1	237
	11th to 20th	Day	24% 17% 28% 17% 11% 2	180
	21st to end	Day	23% 17% 23% 20% 11% 6%	180
December	1st to 10th	Day	16% 18% 21% 21% 20% 4	180
	11th to 20th	Day	21% 18% 29% 19% 11% 2	180
	21st to end	Day	15% 14% 28% 34% 6% 3	198
January	1st to 10th	Night	26% 17% 23% 24% 9% 1	770
	11th to 20th	Night	16% 14% 29% 27% 13% 2	760
	21st to end	Night	16% 14% 27% 28% 13% 2	836
February	1st to 10th	Night	20% 14% 28% 25% 11% 2	760
	11th to 20th	Night	16% 13% 27% 31% 12% 1	722
	21st to end	Night	14% 14% 23% 26% 20% 4	592
March	1st to 10th	Night	18% 14% 25% 26% 16% 2	720
	11th to 20th	Night	17% 16% 26% 23% 16% 2	720
	21st to end	Night	17% 13% 24% 27% 15% 4	792
April	1st to 10th	Night	14% 11% 22% 32% 17% 4	720
	11th to 20th	Night	16% 11% 23% 31% 17% 3	675
	21st to end	Night	14% 12% 26% 31% 14% 3	435
May	1st to 10th	Night	15% 7% 21% 33% 21% 3	360
	11th to 20th	Night	14% 6% 17% 35% 23% 5%	354
	21st to end	Night	17% 6% 16% 27% 28% 6%	389
June	1st to 10th	Night	18% 8% 23% 30% 19% 2	360
	11th to 20th	Night	19% 8% 19% 34% 18% 3	360
	21st to end	Night	9% 6% 19% 37% 26% 4	360
July	1st to 10th	Night	8% 3 16% 31% 38% 3	350
	11th to 20th	Night	5% 6% 20% 35% 31% 4	348
	21st to end	Night	6% 3 14% 35% 37% 5%	394
August	1st to 10th	Night	6% 3 12% 32% 36% 11%	358
	11th to 20th	Night	7% 1 13% 33% 38% 6%	356
	21st to end	Night	10% 5% 16% 35% 30% 4	757
September	1st to 10th	Night	11% 7% 17% 33% 26% 7%	720
	11th to 20th	Night	15% 5% 15% 26% 28% 11%	720
	21st to end	Night	19% 7% 18% 31% 20% 5%	720
October	1st to 10th	Night	17% 8% 19% 28% 24% 4	720
	11th to 20th	Night	20% 11% 20% 26% 20% 3	720
	21st to end	Night	21% 12% 24% 28% 12% 4	792
November	1st to 10th	Night	27% 13% 25% 26% 8% 1	740
	11th to 20th	Night	24% 17% 24% 23% 10% 2	760
	21st to end	Night	21% 15% 26% 25% 11% 3	902
December	1st to 10th	Night	16% 14% 26% 30% 13% 2	950
	11th to 20th	Night	20% 14% 31% 25% 9% 1	950
	21st to end	Night	20% 15% 31% 26% 7% 1	1045

Page generated at 2024-02-12 03:35:34. Version ac07

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